Wednesday, July 31, 2013

Simple Small Portable Alarm Circuit

The system of using this circuit is positioning a little magnet close to the stalk switch SW1 while being connected to the hand or garments of the individual holding the sack with the use of a tiny cable. Since the circuit is tiny, it can be put in a tiny plastic box. The magnetic field will definitely loose its contact with the splint change the moment the bag is snatched instantly. The circuit will definitely start oscillating if SW1 starts and will certainly produce a loud alarm sound from the loudspeaker. Alternatively, the unit can be placed in a pocket while the cable is linked to the bag, to develop a reverse approach of connection.

The high efficiency oscillator is made up by electrical wiring a corresponding transistor-pair that will definitely drive a small 8 Ohm loudspeaker directly. A very compact assembly is the result of 3 V electric battery quantity B1 and reasonable count of parts made use of.

Any kind of loudspeaker can be made use of yet the measurement is directed by the box where it will be positioned. Considering that the standby current being drawn is less than 20 uA, it is not required to include an ON/OFF switch. A existing of around ONE HUNDRED mA is consumed by the circuit when the alarm system is sounding. To make the circuit a lot more appealing, a 3.5 mm mono jack can be made use of as substitute for the switch while a 3.55 mm mono jack plug with its interior leads shorted can be made use of in place of the magnet. The tiny cable will certainly be connected to the jack plug. The voltage used to provide this circuit should not go over 4.5 V since the transistor Q2 could acquire ruined. To be on the risk-free side, it is suggested to utilize a 3 V supply with two AA cells wired in series.

The personal alerts are one of the fastest growing portions in the self protection sector today because they are exceptionally loud as well as beneficial to hold. It could be available in the kind of essential chains, rich torches, levered hook, or hand band. It is utilized for scaring off an attacker by unexpected them with high pitch alarm that may attract attention of others in the spot. The opening of a window or doorway may give a signaling procedure utilizing this gadget which can be done by putting the box on the frame as well as the magnetic field on the transferable part. In this way, the splint switch as well as the magnetic field will definitely be extremely close when the window or doorway is closed.
  • BC547 isNPN tiny signal transistors produced for basic application changing and boosting due to its reasonable voltage, low current as well as 3 different gain options
  • BC327 is a PNP basic purpose transistor in a TO-92 bundle, made use of for basic purpose changing and amp applications which is suitable for AF driver periods and inexpensive power outcome stages of audio amps due to its attributes of high current at FIVE HUNDRED mA maximum and inexpensive voltage at 45 V optimum
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Monday, July 29, 2013

2008 Mercury Sable Passenger Compartment Fuse Panel and Relay Code Diagram


If you found electrical components are not working in a vehicle, a fuse may have blown, so check the appropriate fuses before replacing any electrical component. You can identify the blown fuse by the broken wire within the fuse. The following schematic / diagram shows the location of The 2008 Mercury Sable Passenger Compartment Fuse Panel and Relay. The fuse panel and relay of the 2008 Mercury Sable are located under the instrument panel to the left of the steering wheel.



Always replace the fuse with one that has the specified rating, if the amperage ratings of the replacing fuse is higher, A fuse with higher amperage rating can cause severe wire damage and could start a fire. The table below shows you the exact amperage rating, location and code for each fuse and relay. (fuse number, amperage rating, and circuit protected).


2008 Mercury Sable Passenger Compartment Fuse Panel and Relay Code:

Fuse
Amperage
Description of Circuit Protected

1
2
30A
15A
Smart window motor
Brake on/off switch, High-mounted brake lamp
3
15A
SDARS, Bluetooth, Family entertainment system (FES)/Rear seat control
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
30A
10A
20A
10A
10A
15A
15A
10A
7.5A
5A
10A
10A
15A
20A
20A
25A
15A
15A
15A
15A
20A
10A
10A
20A
5A
5A
5A
10A
10A
10A
5A
Spare
SPDJB logic power
Turn signals
Low beam headlamps (left)
Low beam headlamps (right)
Interior lights, Cargo lamps
Backlighting, Puddle lamps
All wheel drive
Memory seat/mirror switches, Memory module
FEPS module
Analog clock
Climate control
Spare
All power lock motor feeds, Decklid release
Spare
Moon roof
OBDII connector
Fog lamps
Park lamps, License lamps
High beam headlamps
Horn relay
Demand lamps/Interior lamps
Instrument panel cluster
Adjustable pedal switch
Radio, Radio start signal
Instrument panel cluster
Overdrive cancel switch
Compass, Automatic dimming rear view mirror
Restraint control module
Spare
AWD module
35
10A
Steering rotation sensor, FEPS, Rear park assist, Heated seat modules
36
37
38
39
40
41
42
43
44
5A
10A
20A
20A
20A
15A
10A
10A
10A
PATS module
Climate control
Subwoofer (Audiophile radio)
Radio
Spare
Mic mirror, Moon roof, Front lock switches, Radio
Spare
Spare
Spare
45
5A
Relay coils: PDB, Auxiliary A/C, Front and rear wipers, Front blower motor
46
7.5A
Occupant Classification Sensor (OCS), Passenger Airbag Deactivation Indicator (PADI)
47
48
30A CB*
-
Power windows
Delayed accessory relay



* CB: Circuit Breaker
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Thursday, July 25, 2013

Mains Supply Failure Alarm


Whenever AC mains supply fails, this circuit alerts you by sounding an alarm. It also provides a backup light to help you find your way to the torch or the generator key in the dark. The circuit is powered directly by a 9V PP3/6F22 compact battery. Pressing of switch S1 provides the 9V power supply to the circuit. A red LED (LED2), in conjunction with zener diode ZD1 (6V), is used to indicate the battery power level.

Resistor R9 limits the operating current (and hence the brightness) of LED2. When the battery voltage is 9V, LED2 glows with full intensity. As the battery voltage goes below 8V, the intensity of LED2 decreases and it glows very dimly. LED2 goes off when the battery voltage goes below 7.5V. Initially, in standby state, both the LEDs are off and the buzzer does not sound. The 230V AC mains is directly fed to mains-voltage detection optocoupler IC MCT2E (IC1) via resistors R1, R2 and R3, bridge rectifier BR1 and capacitor C1.

Illumination of the LED inside optocoupler IC1 activates its internal phototransistor and clock input pin 12 of IC2 (connected to 9V via N/C contact of relay RL1) is pulled low. Note that only one monostable of dual-monostable multivibrator IC CD4538 (IC2) is used here. When mains goes off, IC2 is triggered after a short duration determined by components C1, R4 and C3. Output pin 10 of IC2 goes high to forward bias relay driver transistor T1 via resistor R7.

Circuit diagram:
mains supply failure alarm circuit schematic
Mains Supply Failure Alarm Circuit Diagram

Relay RL1 energises to activate the piezo buzzer via its N/O contact for the time-out period of the monostable multivibrator (approximately 17 minutes). At the same time, the N/C contact removes the positive supply to resistor R4. The time-out period of the monostable multivibrator is determined by R5 and C2. Simultaneously, output pin 9 of IC2 goes low and pnp transistor T2 gets forward biased to light up the white LED (LED1).

Light provided by this back-up LED is sufficient to search the torch or generator key. During the mono time-out period, the circuit can be switched off by opening switch S1. The ‘on’ period of the monostable multivibrator may be changed by changing the value of resistor R5 or capacitor C2. If mains doesn’t resume when the ‘on’ period of the monostable lapses, the timer is retriggered after a short delay determined by resistor R4 and C3.
 
 
Source: EFY Mag
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Saturday, July 13, 2013

2 Watt FM Transmitter

CIRCUIT DESCRIPTION
The circuit is basically a radio frequency (RF) oscillator that operates around 100 MHz. Audio picked up and amplified by the electret microphone is fed into the audio amplifier stage built around the first transistor. Output from the collector is fed into the base of the second transistor where it modulates the resonant frequency of the tank circuit (L1 coil and the trimcap) by varying the junction capacitance of the transistor. Junction capacitance is a function of the potential difference applied to the base of the transistor T2. The tank circuit is connected in a Hartley oscillator circuit.

Components List

R1=220K
R2=4.7K
R3,R4=10K
R5=100ohm
C1,C2=4.7uF Electrolytic
C3,C4=1nF
C5=2-15pF
C6=3.3pF
Q1=BC547C
Q2=BD135
P1=25K
MIC=Electret Condenser Type
P1 act as condenser microphone volume level. For FM, coil will be small. Use thin gauge enamel magnet wire. the diameter of coil will be a couple mm: use ink tube from pen to form, and try 8-12 turns. Small inductance coils link

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Test Beeper For Your Stereo

The test beeper generates a sinusoidal signal with a frequency of 1,000 Hz, a common test  frequency for audio amplifiers.  It consists of a classical Wien- Bridge oscillator (also known as  a Wien-Robinson oscillator). The network that determines the  frequency consists here of a series connection of a resistor and  capacitor (R1/C1) and a parallel connection (R2/C2), where  the values of the resistors and  capacitors  are  equal  to  each  other. This network behaves, at  the oscillator frequency (1 kHz  in this case), as two pure resistors. The opamp (IC1) ensures  that the attenuation of the net- work  (3  times)  is  compensated  for.  In  principle  a  gain  of  3 times should have been sufficient to sustain the oscillation,  but  that  is  in  theory.  Because  of tolerances in the values, the  amplification needs to be (automatically) adjusted.

Circuit diagram:
Test Beeper For Your Stereo circuit-Diagram
Test Beeper For Your Stereo circuit Diagram

Instead of an intelligent amplitude  controller  we  chose  for  a  somewhat simpler solution. With  P1, R3 and R4 you can adjust  the gain to the point that oscillation takes place. The range of P1 (±10%) is large enough the cover the tolerance range. To sustain  the oscillation, a gain of slightly  more than 3 times is required,  which  would,  however,  cause  the amplifier to clip (the ‘round-trip’ signal becomes increasingly  larger, after all). To prevent this  from happening, a resistor in se-ries with two anti-parallel diodes  (D1 and D2) are connected in  parallel  with  the  feedback  (P1  and R3). If the voltage increases to the point that the threshold  voltage of the diodes is exceed-ed, then these will slowly start to  conduct.

The consequence of this  is that the total resistance of the  feedback  is  reduced  and  with  that  also  the  amplitude  of  the  signal. So D1 and D2 provide a  stabilising function. The distortion of this simple oscillator, after adjustment of P1 and  an output voltage of 100 mV (P2  to  maximum)  is  around  0,1%.  You can adjust the amplitude of  the output signal with P2 as required for the application. The  circuit is powered from a 9-V battery. Because of the low current  consumption  of  only  2 mA  the  circuit will provide many hours  of service.
Author :Ton Giesberts  - Copyright : Elektor Electronics
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Going for Gold

The title refers to a popular TV game show where the contestants each have a big button.  The  game show  host  asks  a  question and the first contestant to press their but-ton makes an illuminated indicator light up on their desk. The other contestants’ buttons  are automatically inhibited, so that everyone can see who was the first contestant to press their button, and so is allowed to answer the question. The project described here shows how to build a similar sortof  refereeing device yourself, using simple resources and without needing a microcontroller, which is  pretty rare these days! The basic circuit is for  just two contestants, but the modular design  means it can easily be expanded.

Circuit diagram :
 Going for Gold-Circuit-Diagram
Going for Gold Circuit Diagram

The diagram shows three buttons: S2 and S3  are the buttons for the two contestants, S1 is  the button for the host, which allows them to  reset the circuit before each fresh question.  The ‘brains’ of the circuit is IC1, a 4013 dual D-type flip-flop, of which only the Set and Reset  inputs are used here. This circuit can handle  quite a wide supply voltage range, from 3 to  15 V, and so the project can easily be run off a 4.5 V battery pack (the power consumption is minimal).

IC1 is armed by pressing S1 (reset). In this  state, the non-inverting outputs (pins 1 and  13) are at 0 and the inverting outputs (pins 12  and 12) are at 1. Hence line A is pulled high  by R1, since diodes D2 and D4 are not biased  on. If contestant 1 presses button S2, the  non-inverting output of flip-flop IC1a goes  to logic 1, and LED D1 lights via T1 to indicate that contestant 1 has pressed the but-ton. At the same time, the flip-flop’s invert-ing output goes to logic 0, making diode  D2 conduct. Line A is now pulled down to 0,  and consequently contestant 2’s button S3  can no longer trigger the second flip-flop.  The reverse happens if it is contestant 2 who  presses their button S3 first.

The circuit can be extended to 4 or 6 contest-ants (or even more) by adding a second or  third (or more) 4013 IC. All you have to do is  repeat the circuit (minus R1, R2, and S1) and connect to the A, B, Vdd, and 0 V lines on the right-hand side. 
 
 
Streampowers
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Friday, July 12, 2013

Build a LT3582 12 DC 5V to 12V DC Converter

Using LT3582-12 dual channel DC DC converter integrated circuit, manufactured by Linear Technology, can be designed a very simple step up dc converter. This 5 to 12V c converter electronic project provide both positive and negative outputs required in many biasing applications such as active matrix OLED (organic light-emitting diode)displays as well as CCD (charge coupled device) applications.

Build a LT3582-12 DC 5V to 12V DC Converter

The LT3582 offer an I2C interface that can dynamically program output voltages, power sequencing and output voltage ramps as the application requires. The LT3582’s positive output voltage can be set between 3.2V and 12.775 in 25mV steps, whereas the negative output can be set between -1.2V and -13.95V in 50mV steps. The LT3582-12 is preconfigured with ±12V output, requiring no future programming.
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Versatile Micropower Battery Protector

Protect your expensive batteries from discharge damage with this mini-sized electronic cutout switch. It uses virtually no power and can be built to suit a wide range of battery voltages.
Main Features
  • Disconnects load at preset battery voltage
  • Automatically reconnects load when battery recharged
  • Ultra-low power consumption (<20ma)
  • Miniature size
  • 10A maximum rating
  • Suitable for use with 4.8-12.5V batteries
  • Transient voltage protection (optional)
Suitable for use in...
  • Cars, boats & caravans
  • Security systems
  • Emergency lighting
  • Small solar installations
  • Camera battery packs
  • Many other low-power applications
Picture of the project:
versatile-micropower-battery-protector-circuit1
versatile-micropower-battery-protector-circuit-backside 2

Back in May 2002, we (Silicon Chip) presented the "Battery Guardian", a project designed specifically for protecting 12V car batteries from over-discharge. This unit has proven to be very popular and is still available from kit suppliers. This new design does not supersede the Battery Guardian – at least not when it comes to 12V car batteries. Instead, it’s a more flexible alternative that can be used with a wide range of battery voltages.

Parts layout:
front-parts-layout-versatile-micropower-battery-protector-circuit 3
back-parts-layout-versatile-micropower-battery-protector-circuit 4

In this new "Micropower Battery Protector", we’ve dispensed with the low-battery warning circuitry and the relatively cheap N-channel MOSFET used in the Battery Guardian in favour of a physically smaller module that steals much less battery power. It costs a little more but can switch lower voltages, allowing it to be used with 6V & 12V lead-acid batteries and 4-cell to 10-cell NiCd and NiMH battery packs.

PCB layout:
pcb-layout-versatile-micropower-battery-protector-circuit 5

Most battery-powered equipment provides no mechanism for disconnecting the batteries when they’re exhausted. Even when the voltage drops too low for normal operation, battery drain usually continues until all available energy is expended. This is particularly true of equipment designed to be powered from alkaline or carbon cells but retro-fitted with rechargeables.

Circuit diagram:
versatile-micropower-battery-protector-circuit-diagram 6

Another example is emergency lighting and security equipment designed to be float-charged from the mains. In an extended blackout period, the batteries can be completely drained and may not recover when the mains power is finally restored.
Source: Silicon Chip 27 July 2004
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Build a 65W Notebook Laptop Power Adapter

Using TOP269EG off-line switcher IC, (U1), in a flyback configuration can be designed a very simple high efficiency notebok laptop power adapter.TOP269EG IC has an integrated 725 V MOSFET and a multi-mode controller. It regulates the output by adjusting the MOSFET duty cycle, based on the current fed into its CONTROL pin.This laptop power adapter circuit will provide a fixed 19 volts output voltage at a maximum current of 3.5A. input voltage range is between 90 to 265VAC.


Common-mode inductors L3 and L4 provide filtering on the AC input. X class capacitor C1 provides differential filtering, and resistors R1 and R2 provide safety from shock if the AC is removed, by ensuring a path for C1 to discharge. This is required by safety agencies when the capacitor value exceeds 100 nF. Bridge rectifier D1 rectifies the AC input, and bulk capacitor C2 filters the DC.



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Build a Radio Wave Alarm

This simple circuit is sure to have the police beating a path to your door- however, it has the added advantage of alerting you to their presence even before their footsteps fall on the doormat.

Simple Radio Wave Alarm Circuit Diagram :
Build a Radio Wave Alarm

Notes :
  • The circuit transmits on Medium Wave (this is the small problem with the police). IC1a, together with a sensor (try a 20cm x 20cm sheet of tin foil) oscillates at just over 1MHz. This is modulated by an audio frequency (a continuous beep) produced by IC1b. When a hand or a foot approaches the sensor, the frequency of the transmitter (IC1a) drops appreciably.
  • Suppose now that the circuit transmits at 1MHz. Suppose also that your radio is tuned to a frequency just below this. The 1MHz transmission will therefore not be heard by the radio. But bring a hand or a foot near to the sensor, and the transmitters frequency will drop, and a beep will be heard from the radio.
  • Attach the antenna to a multiplug adapter that is plugged into the mains, and you will find that the Medium Wave transmission radiates from every wire in your house. Now place a suitably tuned Medium Wave radio near some wires or a plug point in your house, and an early-warning system is set up.
  • Instead of using the sheet of tin foil as the sensor, you could use a doorknob, or burglar bars. Or you could use a pushbutton and series resistor (wired in series with the 33K resistor - the pushbutton would short it out) to decrease the frequency of IC1a, so activating the system by means of a pushbutton switch. In this case, the radio would be tuned to a frequency just below that of the transmitter.
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Thursday, July 11, 2013

High intensity LED Warning Flasher Circuit Diagram

This circuit was designed as a warning flasher to alert road users to dangerous situations in the dark. Alternatively, it can act as a bicycle light (subject to traffic regulations and legislation). White LEDs only are recommended if the circuit is used as a bicycle front light (i.e. for road illumination) and red LEDs only when used as a tail light. During the day, the two 1.6-V solar cells charge the two AA batteries. In darkness, the solar cell voltage disappears and the batteries automatically power the circuit. 
High-intensity LED Warning Flasher Circuit Diagram
High-intensity LED Warning Flasher

The flash frequency is about one per second and the LED on-time is about 330 ms. The duty cycle should enable the batteries to power the circuit over night. The circuit is composed of three parts. Under normal daylight conditions the batteries are charged through diode D4. In darkness, pnp transistor T1 is switched on, supplying battery current to the second part, a low-frequency oscillator comprising T2 and T3.The third part is the LED driver around T4.

It conducts and switches on the LEDs D1-D2-D3 when the collector voltage of T3 swings high. Two LEDs (D1, D2) are 20,000-30,000 mcd high-brightness yellow types and one (D3) is a normal 3-mm red LED for control purposes. Of course it is possible to increase the number of LEDs to obtain higher brightness. However you will run into limitations regarding the maximum collector current of transistor T4. For really high power applications a MOSFET transistor is suggested instead of the common or garden BC547B.



Author: Jose Luis Basterra - Copyright: Elektor
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Stepper Motor Controller Using by A3952S

Using the A3952S stepper motor controller ( designed by Allegro MicroSystems ) we can design a very simple and useful motor driver circuit that can be used in many electronic applications . A3952S stepper motor controller is capable of continuous output currents up to 2 A and operating voltages range up to 50 V. Internal fixed off-time PWM current-control circuitry can be used to regulate the maximum load current to a desired value. The MODE terminal can be used to optimize the performance of the device in microstepping / sinusoidal stepper motor drive applications.

A3952S Stepper Motor Controller Circuit diagram


When the average load current is increasing, slow-decay mode is used to limit the switching losses in the device and iron losses in the motor. The thermal performance in applications with high load currents and/or high duty cycles can be improved by adding external diodes in parallel with the internal diodes. In internal PWM slow-decay applications, only the two top-side (flyback) diodes need be added. For internal fast-decay PWM, or external PHASE or ENABLE input PWM applications, all four external diodes should be added for maximum junction temperature reduction .

As you can see in the schematic diagram , this stepper motor driver circuit require two A3952S circuits and other few additional electronic components.
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Mains Frequency Monitor

Here is a simple frequency counter designed to monitor the 240VAC mains supply. It as a frequency range of 0-999Hz, so it could also be used with 400Hz equipment. Standard TTL/CMOS logic is employed for the counters and display drivers, while an ELM446 (IC1) generates accurate 1Hz pulses for gating. This device utilizes a 3.579545MHz crystal for its timebase, as commonly found in TV and video circuits and even on old PC motherboards.

Circuit diagram:
mains-frequency-monitor-circuit diagram
Mains Frequency Monitor Circuit Diagram


Source by : Streampowers
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1 4 wavelength Active Antenna

Antennas are much shorter than quarter wavelength impedance obtained is very small and highly dependent on the frequency. It was a difficult game impedances over a decade of frequency coverage. Instead, the phase of the input source-follower FET Q1. A high impedance input successfully bridges Antenna characteristics at any frequency.

1/4 wavelength Active Antenna Circuit Diagram
 

transistor Q2 is used as a follower, to provide a high impedance load for Q1, but more importantly that it makes to drive low-impedance amplifier coupled to commonly Q3, which each receive a voltage amplifier. Q3 Q4 turns transistor output impedance is relatively low in impedance, which is enough to drive 50 Three dimensional receiver, Antenna input impedance.
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Digital Clock with Timer and Solar Panel Regulator

This is a combination digital clock timer and solar panel charge controller used to maintain a deep cycle battery from a solar panel. The timer output is used to control a 12 volt load for a 32 minute time interval each day. Start time is set using 9 dip switches and ends 32 minutes later. The 32 minute duration is set by selecting the 5th bit (2^5 = 32) of a 4040 binary counter (pin 2). The timer also has a manual toggle switch so the load can be manually switched on or off and automatically shuts off after 32 minutes. The time duration can be longer or shorter (8,16,32,64,128,256 minutes etc.) by selecting the appropriate bit of the counter. The timer circuit is shown in the lower schematic just above the regulator.  

Basic Clock Circuit diagram


Digital Clock with Timer and Solar Panel Regulator


The basic clock circuit (top schematic below) is similar to the binary clock (on another page) and uses 7 ICs to produce the 20 digital bits for 12 hour time, plus AM and PM. A standard watch crystal oscillator (32,768) is used as the time base and is divided down to 1/2 half second by the 4020 binary counter. One half of a 4013 data latch is used to divide the 1/2 second signal by 2 and produce a one second pulse that drives the seconds counter (74HC390 colored purple). The minutes are advanced by decoding 60 seconds (40 + 20) and then resetting the seconds counter to 0 and at the same time advancing the minutes counter. The same procedure is used to advance the hours. The second half of the 4013 latch is used to indicate AM or PM and is toggled by decoding 13 hours and resetting the hours to 0 and then advancing the hours to "one".


Clock Display Circuit diagram
Digital Clock with Timer and Solar Panel Regulator


The clock display circuit is shown in the second drawing below and uses 6 more ICs to decode the binary data and drive four seven segment LED displays. The 10s of hours digit is driven with a single 3904 transistor. Two multiplexer circuits (4053) are used to manually select either minutes or seconds for the right two display digits. The two switches shown between the 4053s and below the left 4053 are both part of one DPDT switch which selects either seconds or minutes for the 1X and 10X digits. This switch is shown in the seconds position and the hours digits are blanked with a low signal on pin 4 of the 4511.

The display can also be toggled on and off (totally blank) using a set/reset latch made from a couple 74HC00 NAND gates. A momentary DPDT switch is used to control the latch and toggle the display on or off. The second pole of this switch is used on the upper drawing (connected to the run/stop switch) to set the hours and minutes. Thus this same switch performs both functions of blanking the display and setting the time. The run/stop switch is shown in the normal running mode and supplies a low signal to a NAND gate which prevents accidental setting the time while the clock is running.

 Clock Timer Circuit diagram


Digital Clock with Timer and Solar Panel Regulator


The run/stop switch also turns on the display (through the diode D2) when in the stop position. The procedure for setting the clock would be to set the (run/stop) switch the stop position and the (seconds/minutes) switch to the minutes position. Then toggle the momentary switch to set minutes and hours of the current time plus one minute. The clock can then be started with the run/stop switch at precisely the right time (+/- 0.5 seconds).

Voltage Regulator (13.6 volts)

Digital Clock with Timer and Solar Panel Regulator


The voltage regulator in the lower drawing maintains the battery at 13.6 volts and also supplies the clock and timer circuits with 4.3 volts. The charge LED indicator only comes on when the regulator is supplying max charge to the battery. When the battery voltage reaches 13.6 the regulator reduces the current to whatever is necessary to maintain the voltage and the charge indicator will turn off. The unit I built also included a battery condition indicator (voltmeter using 4 LEDs) to indicate the battery condition so that a failure of the regulator would be indicated by the charge indicator LED turned off and less than 4 LEDs lit on the voltmeter.
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Simple Ignition Timer Schematic

This circuit is a tester for flywheel based ignition systems in small aeroplane engines. Basically the same ignition coils are also seen in other small combustion engines used in/on mopeds and lawn mowers  in brief, engines without a battery. The part to be tested comprises a primary coil in parallel with the contact breaker. The timing of this contact breaker has to be adjusted correctly.
Since the coil’s primary has a very low resistance it is difficult to determine whether the contact breaker is open or closed.  However, you can determine that reliably with this circuit, using an LED and a beeper. The circuit is implemented twice because aviation engines (Cessna, Piper and similar) always have two ignitions in parallel to increase reliability. For two-cylinder engines, well the purpose is obvious.
Ignition Timer Circuit Diagram
The circuit consists of a 555 and a few transistors. The 555 supplies a square wave of about 3000 Hz. This signal goes to power transistors T1 and T2; these can supply quite a bit of power and are robust enough to withstand the voltage transients from the big coils. The test connection (K2 and K3 respectively) are connected in parallel with the contact breaker to be tested, which itself is in parallel with the ignition coil. The frequency of 3000 Hz is either short circuited by the contact breaker or if the points are open  is amplified somewhat by the resonance of the coil itself.

This allows you to reliably detect the difference bet ween a closed and open contact breaker, despite the low resistance of the coil, which is in parallel with it. When the contact breaker is open the amplified pulses will turn on T3 and T4 respectively, so that the relevant LEDs turn on and the buzzer will sound.

The components are not critical, but do use a sensitive type for the piezo buzzer. The power supply is 3 V (2 times AA or AAA batteries). Link
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Wednesday, July 10, 2013

Mains Manager

Very often we forget to switch off the peripherals like monitor, scanner, and printer while switching off our PC. The problem is that there are separate power switches to turn the peripherals off. Normally, the peripherals are connected to a single of those four-way trailing sockets that are plugged into a single wall socket. If that socket is accessible, all the devices could be switched off from there and none of the equipment used will require any modification. 

Here is a mains manager circuit that allows you to turn all the equipment on or off by just operating the switch on any one of the devices; for example, when you switch off your PC, the monitor as well as other equipment will get powered down automatically. You may choose the main equipment to control other gadgets. 

The main equipment is to be directly plugged into the master socket, while all other equipment are to be connected via the slave socket. The mains supply from the wall socket is to be connected to the input of the mains manager circuit. The unit operates by sensing the current drawn by the control equipment/load from the master socket. On sensing that the control equipment is on, it powers up the other (slave) sockets.

The load on the master socket can be anywhere between 20 VA and 500 VA, while the load on the slave sockets can be 60 VA to 1200 VA. During the positive half cycle of the mains AC supply, diodes D4, D5, and D6 have a voltage drop of about 1.8 volts when current is drawn from the master socket. Diode D7 carries the current during negative half cycles. Capacitor C3, in series with diode D3, is connected across the diode combination of D4 through D6, in addition to diode D7 as well as resistor R10. Thus current pulses during positive half-cycles, charge up the capacitor to 1.8 volts via diode D3. 

This voltage is sufficient to hold transistor T2 in forward biased condition for about 200 ms even after the controlling load on the master socket is switched off. When transistor T2 is ‘on’, transistor T1 gets forward biased and is switched on. This, in turn, triggers Triac 1, which then powers the slave loads. Capacitor C4 and resistor R9 form a snubber network to ensure that the triac turns off cleanly with an inductive load.

Circuit diagram:
mains-manager circuit diagram
Mains Manager Circuit Diagram

LED1 indicates that the unit is operating. Capacitor C1 and zener ZD1 are effectively in series across the mains. The resulting 15V pulses across ZD1 are rectified by diode D2 and smoothened by capacitor C2 to provide the necessary DC supply for the circuit around transistors T1 and T2. Resistor R3 is used to limit the switching-on surge current, while resistor R1 serves as a bleeder for rapidly discharging capacitor C1 when the unit is unplugged. LED1 glows whenever the unit is plugged into the mains. Diode D1, in anti-parallel to LED1, carries the current during the opposite half cycles. Don’t plug anything into the master or slave sockets without testing the unit.

If possible, plug the unit into the mains via an earth leakage circuit breaker. The mains LED1 should glow and the slave LED2 should remain off. Now connect a table lamp to the master socket and switch it ‘on’. The lamp should operate as usual. The slave LED should turn ‘on’ whenever the lamp plugged into slave socket is switched on. Both lamps should be at full brightness without any flicker. If so, the unit is working correctly and can be put into use.

Note:
  1. The device connected to the master socket must have its power switch on the primary side of the internal transformer. Some electronic equipment have the power switch on the secondary side and hence these devices continue to draw a small current from the mains even when switched off. Thus such devices, if connected as the master, will not control the slave units correctly. 
     
  2. Though this unit removes the power from the equipment being controlled, it doesn’t provide isolation from the mains. So, before working inside any equipment connected to this unit, it must be unplugged from the socket.


Source by : Streampowers
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Simple HiFi Expandor Circuit Diagram with De emphasis

This is the schematic design of HiFi Expandor Circuit with De-emphasis. The circuit is based NE570. The NE570 can be used to construct a high performance compandor suitable for use with music. This type of system can be used for noise reduction in tape recorders, transmission systems, bucket brigade delay lines, and digital audio systems. The circuits to be described contain features which improve performance, but are not required for all applications.

 HiFi Expandor Circuit  Diagram 
HiFi Expandor Circuit  Diagram

The expandor to complement the compressor is shown in the above circuit. Here an external op amp is used for high slew rate. Both the compressor and expandor have unity gain levels of 0dB. Trim networks are shown for distortion (THD) and DC shift. The distortion trim should be done first, with an input of 0dB at 10kHz. The DC shift should be adjusted for minimum envelope bounce with tone bursts. When applied to consumer tape recorders, the subjective performance of this system is excellent.
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LED Torch using NSI45090JDT4G Constant Current Regulator

A very simple LED torch can be designed using the NSI45090JDT4G adjustable constant current regulator (CCR) designed by ON Semiconductor ,using extreme few external components. NSI45090JDT4G device is designed to provide a cost effective solution for regulating current in LEDs. This Constant current regulator is based on patent-pending Self-Biased Transistor (SBT) technology and regulates current over a wide voltage range. It is designed with a negative temperature coefficient to protect LEDs from thermal runaway at extreme voltages and currents.

LED Torch Circuit Diagram



LED Torch using NSI45090JDT4G Constant Current Regulator

The Radj pin allows Ireg(SS) to be adjusted to higher currents by attaching a resistor between Radj (Pin 3) and the Cathode (Pin 4). The Radj pin can also be left open (No Connect) if no adjustment is required.The maximum current that can be adjusted using this chip is around 160 mA , and the maximum input voltage is around 45 volts The D1 from the circuit shown here is used for reverse battery protection .

Bellow you can see how simple is to design a circuit using this chip ( all data shown bellow are for this schematic ) .
LED’s = ((Vin − QX VF − D1 VF)/LED VF)
Example: Vin = 12 Vdc, QX VF = 3.5 Vdc, D1VF = 0.7 V
LED VF = 2.2 Vdc @ 30 mA
(12 Vdc − 4.2 Vdc)/2.2 Vdc = 3 LEDs in series.
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Zener Diode Tester

In this schematic circuit is presented a very simple Zener Diode Tester circuit that require few external components to  be build .

Zener Diode Tester Circuit diagram

As you can see in the schematic circuit , the Zener Tester  project is based on a common 741 operational amplifier .The supply need only be as high a value as the zener itself . The variable resistor P can be calibrated ( in volts ) , so when the LED 1 lights the voltage on pins 2 and 3 of the 741 operational amplifier is nearly equal .
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Tuesday, July 9, 2013

12KV High Voltage Generator

The hobby circuit below uses an unusual method to generate about 12,000 volts with about 5uA of current. Two SCRs form two pulse generator circuits. The two SCRs discharge a 0.047uF a 400v capacitor through a xenon lamp trigger coil at 120 times a second.

Circuit Project:12KV High Voltage Generator
 
The high voltage pulses produced at the secondary of the trigger coil are rectified using two 6KV damper diodes. The voltage doubler circuit at the secondary of the trigger coil charges up two high voltage disc capacitors up to about 12KV. Although this circuit can’t produce a lot of current be very careful with it. A 12KV spark can jump about 0.75 of an inch so the electronic circuit needs to be carefully wired with lots of space between components.
 
 
 
Source by : Streampowers
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2500W Phase Control

This circuit controls resistive and inductive loads up to 2,500W. Its main functional device is an integrated phase control circuit - Siemens TLE3103. It contains its own power supply, a zero voltage crossing detector circuit and a logic driver. An additional feature is the low voltage input to enable/disable triac firing enabling/disabling the logic driver. The function is as follows: pin13 TLE3103 open (floating), trigger output active, tied to ground trigger output disabled.

2500W Phase Control  Circuit diagram


An UP and a DOWN button control a 32-step digital potentiometer (IC2, AD5228) via the debouncer IC1 (MAX6817). The potentiometer has a power on reset pin which might be tied to ground causing the potentiometer to start at midscale, or to VCC causing it to start at zero scale. The desired function is selectable using jumper JP1. The triac (capable of driving 40A loads) is a bit overkill for the desired power but the BTA41 has an isolated body and therefore handling of the board under voltage is less dangerous as it is with phase on the package. The circuit uses a 68μH inductance, but this might be replaced with a 100 resistor, then replacing the inductance C5 should have a value of 47nF.
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LTC2990 System Monitoring IC

Using LTC2990 integrated circuit you can design a very simple monitoring system to monitor system temperatures, voltages and currents. Through the I2C serial interface, the device can be configured to measure many combinations of internal temperature, remote temperature, remote voltage, remote current and internal VCC. The internal 10ppm/°C reference minimizes the number of supporting components and area required. Selectable address and configurable functionality give the LTC2990 flexibility to be incorporated in various systems needing temperature, voltage or current data.

Bellow you can see some ideas how to use the LTC2990 I2C Temperature, Voltage and Current Monitor Ic in your electronic projects .

You can use LTC2900 IC for electronic projects like :motor protection , fan temperature alarm , battery monitoring , liquid level sensing and many other projects .


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Simple OBD Vehicle Protection

vehicle immobilisers are fitted as standard to modern cars and heavy goods vehicles. Anti-theft mechanisms have become more sophisticated but so have the methods employed by crooks. Nowadays once the thief has gained access to a vehicle they will most likely use an electronic deactivation tool which seeks to disable the immobiliser, once this has been accomplished a blank transponder key/card can be used to start the engine. In many cases communication with the immobiliser is made using the OBD-II diagnostic connector.

Although the OBD-II protocol itself does not support the immobiliser, the vehicle manufacturer is free to use the interface as neces-sary for communication, either the standard OBD-II signals or unused pins in the OBD-II connector (i.e. those undefined in the OBD-II standard). Using one of these pathways the immobiliser can usually be electronically disabled. 

OBD Vehicle Protection Circuit Diagram
OBD-Vehicle-Protection-Circuit Diagram
This may be unsettling news for owners of expensive vehicles but when professional car-thieves call, armed with the latest OBD-II hacking equipment this simple low-cost low-tech solution may be all that you need. The idea is ver y simple: if all connections to the OBD-II connector are disconnected there is no possibility for any equipment, no matter how sophisticated to gain access via the vehicle’s wiring. 

The OBD-II connector is usually locate d underneath the dashboard on the passenger side; once its wiring loom has been identified a switch can be inserted in line with the wires. The switch should be hidden away some-where that is not obvious. In normal opera-tion you will be protected if the vehicle is run with the wires to the socket disconnected. Make sure however that you throw the switch reconnecting the socket before you next take the vehicle along to a garage for servicing or fault diagnosis. 

The diagram shows the ISO K and ISO L wires switched. To cover all bases it is wise for every wire to the socket is made switchable except the two earth connections on pins 4 and 5 and the supply voltage on pin 16. Almost ever y vehicle manufacturer has their own method of vehicle immobilisation, by disconnecting every wire it ensures that no communication is possible (even over the CAN bus). Now the innermost workings of your vehicle will be safe from prying eyes. When a hacker plugs in a deactivation tool it will power up as normal but probably report something like ‘protocol unrecognised’ when any communication with the OBD port is attempted. 




Author : Florian Schäffer - Copyright: Elektor
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Monday, July 8, 2013

Zener Diode Tester Schematic

Using electronic scheme below can be designed a zener diode tester using few electronic parts. Using this zener tester and a multimeter can be measured and determined with a high precision threshold voltage of a zener diode.Zener voltage can be read with a DC voltmeter connected in parallel with zener diode.
 
Zener Diode Tester Circuit Schematic Diagram


If contact S1 is closed, the resistance R1, T1 and Zener diode current flow. Base transistor T1 is connected to power supply trough the R4, so the transistor conducts.

Zener current is equal to the ratio of base-emitter voltage of Q2 and the resistance value R1. With a supply voltage of 25 volts at the actuation keys S1-S3, the current through zener diode take values of about 2.2,6 and 22mA. Resistances R2 and R3 or a combination of R1, R2, R3 can be connected in place of R1 with S2-S3 so that through the zener diode constant current flow.

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Electrical Isolation For I2C Bus

When the SDA (Serial DAta) lines on both the left and right lines are 1, the circuit is quiescent and optoisolators IC1 and IC2 are not actuated. When the SDA line at the left becomes 0, current flows through the LED in IC1 via R2. The SDA line at the right is then pulled low via D2 and IC1. Optoisolator IC2 does not transfer this 0 to the left, because the polarity of the LED in IC2 is the wrong way around for this level. This arrangement prevents the circuit holding itself in the 0 state for ever. As is seen, the circuit is symmetrical. So, when the SDA line at the right is 0, this is transferred to the left. The lower part of the diagram, intended for the SCL (Serial CLock) line, is identical to the upper part.

Circuit diagram :
Electrical isolation_for_I2C_bus_Circuit Diagram
Electrical Isolation For I2C Bus Circuit Diagram

Resistors R1, R4, R5, and R8, are the usual 3.3 kΩ pull-up resistors that are obligatory in each I2C line. If these resistors are already present elsewhere in the system, they may be omitted here. The current drawn by the circuit is slightly larger than usual since the pull-up resistors are shunted by the LEDs in the optoisolators and their series resistors. Nevertheless, it remains within the norms laid down in the I2C specification.
 
 
 
Source by : streampowers
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Morning Alarm Circuit Diagram Using LDR





Description

          Circuit showing a morning alarm.Here we have used a switching transistor.When the sun rise up ldr is low resistance so the ldr is conduct and a positive volt coming to the base of the Q1 there for the transistor will switch.This time  the buzzer is ON . Adjust the preset control the intensity of light.Manually cut off the power.Are you interested please comment and join this site


Component Required

                Resistor  4.7k preset  , LDR

                Transistor   BC 548

                Buzzer




Source by : http://www.electronics-circuits.in/2012/01/morning-alarm.html


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AM Radio Receiver Using by TEA5551T

Using TEA5551T monolithic integrated radio circuit can be designed a AM radio receiver circuit which is designed for use as a portable radio receiver with headphones . 

AM Radio Receiver Circuit diagram

The TEA5551T radio receiver circuit contains all is needed for a AM radio receiver circuit (a complete AM part and dual AF amplifier with low quiescent current).The TEA5551T support a input voltage range (VS) from 1.8 V to 4.5 V but the typical voltage is 3 volts .Because in most case we don’t find to buy inductors you need to build the inductors L1 , L2 , L3 . In the picture bellow you can see the construction data for these three inductors .
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Metal Detector Schematic Using CS209A

A very simple metal detector electronic project circuit can be designed using the CS209A integrated circuit manufactured by Cherry Semiconductor.The CS209A integrated circuit is a bipolar monolithic integrated circuit for use in metal detection proximity sensing applications.The CS209A metal detector contains two on-chip current regulators, oscillator and low-level feedback circuitry, peak detection/demodulation circuit, a comparator and two complementary output stages.The oscillator, along with an external LC network, provides controlled oscillations where amplitude is highly dependent on the Q of the LC tank.

Metal Detector Schematic Circuit Diagram


The detector, is a single 100uH coil. The IC has an integral oscillator the choke forms part of an external LC circuit, its inductance being changed by the proximity of metal objects. It is the change in oscillation that is amplified and demodulated. Led 1 will light and the buzzer will sound when the inductance its changed. Set up is easy : R5 is adjusted with the LC away from any metal source so that the LED lights and buzzer sounds. The control is backed off so that the LED goes out and buzzer stops. When the choke comes into contact with any metal object that alters its inductance, LED 1 and the buzzer will activate.

FOr this electronic project youll need the following electronic parts: R1=220ohms, R2,R5=10k,R3=1k ,C1,C3=2.2nF; C2=10uF. Entire circuit can be powered from a 9 volts battery.
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Sunday, July 7, 2013

Volume Controller Equalizer Using LM1036

This volume controller equalizer electronic project is designed using LM1036 DC tone volume controller with volume and balance circuit for stereo applications .An additional control input of the LM1036 allows loudness compensation to be simply effected.

Volume Controller Equalizer Circuit Using LM1036


The four control inputs of the LM1036 volume controller provides control of the bass, treble, balance and volume functions through application of DC voltages from a remote control system or, alternatively, from four potentiometers which may be biased from a zenner regulated supply provided on the circuit.Each tone response is defined by a single capacitor chosen to give the desired characteristic.
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Hydrophone Booster Amplifier HA2

Hydrophone Booster Amplifier (HA2)
The HP series Hydrophone Booster Amplifier (HA2) amplifies low-level hydrophone signals over a wide range of frequencies. It has a minimum gain of 25dB and an input and output impedance of 50Ω. The HA2 is designed for use with either Precision Acoustics membrane hydrophone or Precision Acoustics HP Series Hydrophone Measurement System, which is shown in Fig 1.
Hydrophone Booster Amplifier
Alternatively, the HA2 may be used when the acoustic signal is provided by a high output impedance hydrophone, such as a GEC-Marconi membrane device, or a conventional hydrophone. In this instance a BNC/MCX adaptor is used which connects directly to the HP Series Submersible Preamplifier, using it as a buffer amplifier, (i.e. the standard Precision Acoustic HP Series configuration shown in Fig 1 is used, but without the interchangeable probe).
The HA2 amplifier is straightforward to use but the following points should be noted:
  • The output of the amplifier should be correctly terminated in 50Ω before operation.
  • The HA2 amplifier is non-inverting but this is of no consequence when used with the HP Series interchangeable probes as their design takes this into account. However when a submersible preamplifier is used as a high impedance buffer amplifier (as in Fig 2) the system output from the HA2 will be inverted as the HP Series Submersible Preamplifier is inverting.
Before Connecting the unit please read WARNING
To Connect
To  Disconnect
1 Connect Output Load 1 Remove RF Input
2 Apply DC Voltage 2 Remove DC Volts
3 Apply RF Input 3 Remove Load

Specification (HA2 Amplifier Only)
Voltage Gain = 25dB minimum
Bandwidth =  50kHz to 125MHz ±1.0dB
Maximum Output Level = 29dBm for 1dB compression (18.1V pk – pk into 50Ω load)
Input Impedance = Nominal 50Ω
Output Impedance  Nominal 50Ω (VSWR 2:1)
Output Noise Level = Typically 70μV pk – pk (bandwidth 125MHz)
Noise Figure = Typically 10dB
Phase = Non-inverting
Terminations:
Front panel = Input BNC socket BNC Output socket
Rear panel Power Requirements = 28v dc output to supply DC Coupler 100/120/220/240V ac, 50 to 60Hz,
7.5W
Operating Temperature = 0 to 50°C
Size = (90mm × 205mm ×194mm)
Weight = 2.6kg
 
 
 
Streampowers
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Off Hook Telephone Line Indicator

The circuit is designed to connect in parallel with the telephone line, to monitor and detect if any telephone in the same line is busy, with the indication of the LED and which is self-powered so that it does not provide any load on a telephone line.

Light Emitting Diode (LED) – a semiconductor diode that is commonly a source of light when electric current pass through it Metal Oxide Semiconductor Field Effect Transistor (MOSFET) – a device utilized for switching and amplification of signals BS108 – a 250 mA and 200 Volts small signal MOSFET designed for high voltage, high speed switching applications such as relay drivers, CMOS logic, line drivers, TTL or microprocessor to high voltage interface and high voltage display drivers Diode Bridge – also known as bridge rectifier which has four diodes arranged in a bridge configuration where the output voltage has the same polarity with either polarity of the input voltage 1N4007 – a general purpose plastic rectifier with reverse voltage from 50 Volts to 1000 Volts and forward current of 1.0 Ampere

When none of the telephone lines is in use or on-hook, the voltage across the line is around 48V. In this state, the gate of transistor Q2 is shorted to its source during the conduction of Q1. This causes the LED to be disabled while Q2 is turned OFF. When one telephone extension along the telephone line changes to off-hook or in use condition, a voltage drop from 5V to 15V is detected. This will in turn cause Q1 to turn OFF because of the very low voltage across the gate of Q1 which is equal to 6% of the line voltage. Transistor Q2 then will be biased at around half of the line voltage.

Off-Hook Telephone Line Indicator Circuit Diagram


Off-Hook Telephone Line Indicator

 The sudden line drop of voltage triggers Q2 to light up the LED that will give a sign that the line is in use. Using the same line, the circuit is unseen with other telephone devices. A current-limiting resistor is used to maintain the low current of LED1 while the local telephone line parameters dictate the variation of other component’s values. The power of the circuit is provided by the telephone line. Other voltage protection may be used with some reliable design in addition to the current-limiting resistor. This is important to avoid any grounding effects from conducting surfaces within the circuit.

To ensure that transistor Q1 is fully biased while the line is free or not in use where LED1 is OFF, a 500K ohm MOSFET trimmer is used for the desired adjustment. A MOSFET is a three-terminal semiconductor component with a conducting channel in its output and a built-in capacitor at its input. To increase the values of any of the two resistors connected to the gate of Q2, a 200V MOSFET can be used in the place of Q2 if BS108 is not available. However, plain transistors like the bipolar junction can be used but with lower values to allow greater currents to pass through the line that is not in use. The bridge rectifier comprising of four 1N4007 diodes are performing the conversion of AC input into DC output.

MOSFET can function in two ways. The first is known as depletion mode wherein the channel shows its maximum conductance in the absence of a voltage on the gate. The second way that the MOSFET can function is known as enhancement mode wherein the device is not conducting even in the absence of a voltage on the gate because no channel is produced. A channel is being created with the application of a voltage to the gate. To generate better conductivity, greater voltage to the gate is required.

MOSFET drivers are applied in electronic motor control for different types of motors. Also, they are specifically used with long duty cycles, high operating frequency above 200 KHZ, lower output power, and wide load variations. The largest application of MOSFETs are the switched mode power supplies and in battery charging applications. In transducer drivers for high power devices such as light bulbs and motors, large current output with a small input is provided by MOSFETs. Since they are more non-linear than BJTs while producing less distortion, they can be utilized with Hi-Fi amplifiers. In constructing integrated circuits, MOSFETs are very useful since they can be made very compact. Although MOSFETs can get damaged by static electricity at higher voltages, they still provide several advantages as compared to other transistors which include faster switching time than BJT, lower losses than BJT, very small switching current, and least effects of temperature.

This telephone line indicator does not only tell when a telephone line is in use if a plurality of telephones are all setup to the same telephone line, but also prevents interruptions during personal calls. Additionally, it can also help to prevent costly and unwanted disruption of modem calls and fax, it alerts a person when a call is done and the phone is free to use, and the LED light indicates the line is in use.

To avoid any injury, it is a prerequisite to take extra precautionary measures when connecting any circuit to the telephone lines, which can produce life-threatening voltages during normal operation. During a lightning storm, it is better to keep distance from telephone lines.. Legal aspects are imposed in different countries for connecting things to telephone lines. The circuit should be better built with a plug-in cord for easy removal in case of fault occurrences. Otherwise, it would be best to consult a licensed telephone operator.
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18 LED Dimmable LED Lamp

This circuit is a dimmable white LED lamp array with 18 LEDs. The lamp brightness is regulated as long as the input voltage is above 10.5V. A low-dropout analog voltage regulator is used for a simple and relatively efficient design. The lamp produces enough light to use as a a reading lamp or a small work lamp. 

Project Image


18 LED Dimmable LED Lamp

Specifications:
  • Power Requirements
  • Input Voltage: 10.5-16V DC
  • Input Current: 11-150mA at 12VDC
Theory:
The 12V DC input voltage is routed through the 1A fuse and the on/off switch. The 1N4001 diode acts as a crowbar device. If reverse polarity is applied, the fuse will blow and the rest of the circuitry will be protected. Power is sent to the LM2941CT voltage regulator IC. The regulator is wired to produce a voltage range from 5.5V (dim) to 8.3V (bright).

18 LED Dimmable LED Lamp Circuit Diagram

18 LED Dimmable LED Lamp

The 4.7K resistor across the 1K brightness adjustment potentiometer produces a non-linear brightness adjustment to compensate for the eyes logarithmic brightness perception response. The LEDs are organized in six series groups of three with a 24 ohm current limiting resistor on each group. This arrangement limits the maximum current through each LED group to around 20mA.

Use:
Connect the DC input terminals to a 12V source, such as a 12V lead acid battery. Be sure to observe the correct polarity. Turn the power switch on and adjust the brightness adjustment for the desired brightness.

Parts:
    1X LM2941CT low-dropout voltage regulator
    1X aluminum heat sink
    1X 1A DC rated fuse
    1X DC switch
    1X 1N4001 diode
    2X 1K 1/4W resistors
    2X 4.7K 1/4W resistors
    6X 24 ohm 1/4W resistors
    1X 1K linear potentiometer
    18X 5mm white LEDs, 20mA max
    1X 22uF 16V electrolytic capacitor
    1X 100nF 25V monoblock capacitor
 
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Saturday, July 6, 2013

IR Remote Control Tester

 Notes:
As I was developing my IR Extender Circuit, I needed to find a way of measuring the relative intensities of different Infra red light sources. This circuit is the result of my research. I have used a photodiode, SFH2030 as an infra red sensor. A MOSFET opamp, CA3140 is used in the differential mode to amplify the pulses of current from the photodiode. LED1 is an ordinary coloured led which will light when IR radiation is being received. The output of the opamp, pin 6 may be connected to a multimeter set to read DC volts. Infra red remote control strengths can be compared by the meter reading, the higher the reading, the stronger the infra red light. I aimed different remote control at the sensor from about 1 meter away when comparing results. For every microamp of current through the photodiode, about 1 volt is produced at the output. A 741 or LF351 will not work in this circuit.  Although I have used a 12 volt power supply, a 9 volt battery will also work here.
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Stepper Motor Controller Using the NJM3771

An very simple stepper motor driver circuit can be designed using the NJM3771 stepper motor driver integrated circuit designed by New Japan Radio Co. Ltd. This stepper motor driver electronic project is very simple to design and require few external components . 

Stepper Motor Controller Circuit diagram


The NJM3771 IC is especially developed for use in microstepping applications in conjunction with the matching dual DAC (Digital-to-Analog Converter) NJU39610. The NJM3771 contains a clock oscillator, which is common for both driver channels; a set of comparators and flip-flops implementing the switching control; and two H-bridges with internal recirculation diodes. Also this stepper motor driver project supports a wide range input voltage : +5 V is required for logic and +10 to +45 V for the motor powering . The maximum output current that is supported by this circuit is around 650 mA per channel. The NJM3771 stepper motor driver has an selectable slow fast current decay for improved high speed Microstepping .

The output current to the motor winding is mainly determined by the voltage at the reference input and the value of the sensing resistor, RS. The voltage across the sensing resistor is fed back to the comparator via a low-pass filter section, to prevent erroneous switching due to switching transients ( the recommended filter component values, 1 kohm and 820 pF). This driver IC is designed for bipolar motors, i.e., motors that have only one winding per phase but unipolar motor, having windings with a center tap, can also be used .
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