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Tuesday, July 2, 2013

PIC Controlled Relay Driver

This circuit is a relay driver that is based on a PIC16F84A microcontroller. The board includes four relays so this lets us to control four distinct electrical devices. The controlled device may be a heater, a lamp, a computer or a motor. To use this board in the industrial area, the supply part is designed more attentively. To minimize the effects of the ac line noises, a 1:1 line filter transformer is used.

The transformer is a 220V to 12V, 50Hz and 3.6VA PCB type transformer. The model seen in the photo is HRDiemen E3814056. Since it is encapsulated, the transformer is isolated from the external effects. A 250V 400mA glass fuse is used to protect the circuit from damage due to excessive current. A high power device which is connected to the same line may form unwanted high amplitude signals while turning on and off. To bypass this signal effects, a variable resistor (varistor) which has a 20mm diameter is paralelly connected to the input.

Another protective component on the AC line is the line filter. It minimizes the noise of the line too. The connection type determines the common or differential mode filtering. The last components in the filtering part are the unpolarized 100nF 630V capacitors. When the frequency increases, the capacitive reactance (Xc) of the capacitor decreases so it has a important role in reducing the high frequency noise effects. To increase the performance, one is connected to the input and the other one is connected to the output of the filtering part.

After the filtering part, a 1A bridge diode is connected to make a full wave rectification. A 2200 uF capacitor then stabilizes the rectified signal. The PIC controller schematic is given in the project file. It contains PIC16F84A microcontroller, NPN transistors, and SPDT type relays. When a relay is energised, it draws about 40mA. As it is seen on the schematic, the relays are connected to the RB0-RB3 pins of the PIC via BC141 transistors. When the transistor gets cut off, a reverse EMF may occur and the transistor may be defected. To overcome this unwanted situation, 1N4007 diodes are connected between the supply and the transistor collectors. There are a few number of resistors in the circuit. They are all radially mounted. Example C and HEX code files are included in the project file. It energizes the next relay after every five seconds.

The components are listed below.
1 x PIC16F84A Microcontroller
1 x 220V/12V 3.6VA (or 3.2VA) PCB Type Transformer (EI 38/13.6)
1 x Line Filter (2x10mH 1:1 Transformer)
4 x 12V Relay (SPDT Type)
4 x BC141 NPN Transistor
5 x 2 Terminal PCB Terminal Block
4 x 1N4007 Diode
1 x 250V Varistor (20mm Diameter)
1 x PCB Fuse Holder
1 x 400mA Fuse
2 x 100nF/630V Unpolarized Capacitor
1 x 220uF/25V Electrolytic Capacitor
1 x 47uF/16V Electrolytic Capacitor
1 x 10uF/16V Electrolytic Capacitor
2 x 330nF/63V Unpolarized Capacitor
1 x 100nF/63V Unpolarized Capacitor
1 x 4MHz Crystal Oscillator
2 x 22pF Capacitor
1 x 18 Pin 2 Way IC Socket
4 x 820 Ohm 1/4W Resistor
1 x 1K 1/4W Resistor
1 x 4.7K 1/4W Resistor
1 x 7805 Voltage Regulator (TO220)
1 x 7812 Voltage Regulator (TO220)
1 x 1A Bridge Diode

http://www.ecircuitslab.com

Remote Controlled Fan Regulator Circuit Diagram

Using this circuit, you can trade the velocity of the fan from your sofa or mattress. Infrared obtainr module TSOP1738 is used to obtain the infrared sign transmitted by using remote keep a watch on. The circuit is powered with the aid of regulated 9V. The AC primarys is stepped down by using transformer X1 to deliver a secondary output of 12V-0-12V. The transformer output is rectified by using full-wave rectifier comprising diodes D1 and D2, filtered via capacitor C9 and regulated through 7809 regulator to provide 9V regulated output. Any button on the remote can be used for keep watch overling the pace of the fan. Pulses from the IR receiver module are utilized as a set off sign to timer NE555 (IC1) by the use of LED1 and resistor R4.

Circuit Diagram :

$\"Remote-Controlled$

Remote-Controlled Fan Regulator Circuit Diagram

IC1 is wired as a monostable multivibrator to prolong the clock given to decade counter-cum-driver IC CD4017 (IC2).Out of the ten outputs of decade counter IC2 (Q0 thru Q9), handiest 5 (Q0 through Q4) are used to control the fan. Q5 output shouldn't be used, while Q6 output is used to reset the counter. Another NE555 timer (IC3) can additionally be wired as a monostable multivibrator. Combination of one of the most resistors R5 via R9 and capacitor C5 controls the pulse width. The output from IC CD4017 (IC2) is applied to resistors R5 via R9. If Q0 is excessive capacitor C5 is charged via resistor R5, if Q1 is high capacitor C5 is charged through resistor R6, and so on.

Optocoupler MCT2E (IC5) is wired as a zero-crossing detector that supplies trigger pulses to monostable multivibrator IC3 all over zero crossing. Opto-isolator MOC3021 (IC4) drives triac BT136. Resistor R13 (47-ohm) and capacitor C7 (0.01µF) mixture is used as snubber network for triac1 (BT136). As the width of the heart beat lowers, firing attitude of the triac increases and velocity of the fan also increases. Thus the rate of the fan increases when we press any button on the faraway control. Assemble the circuit on a general-purpose PCB and house it in a small case such that the infrared sensor can easily receive the signal from the far flung transmitter.

http://www.ecircuitslab.com/2011/09/remote-controlled-fan-regulator-circuit.html

Friday, March 29, 2013

Automatic Temperature Climate Controlled Mains Fan Regulator Dimmer Circuit

The following circuit of a temperature or climate controlled fan speed regulator circuit was requested by one of the followers of this blog Mr.Anil Kumar. Lets learn more about the request and the proposed design.

The Request

Hi Swagatam,

am doing project on automatic speed control of ceiling fan depending on temperature. am an engineering student. can help me abt circuit and all. please...

The Design

As can be seen in the given diagram, a very simple concept has been implemented in the proposed design of a climate controlled or temperature controlled fan regulator circuit.

A1, A2, and A3 are the 3 opamps from the IC LM324 which are configured as voltage comparators and amplifier.

The diode D1 which is a common "garden diode" has a very interesting "drawback", it changes its forward voltage drop by 2mV in response to every degree rise in the ambient temperature or the temperature surrounding it.

The above drawback of the device becomes our benefit here, because the feature here is exploited for sensing the ambient temperature of the premise.

The varying voltage across D1, in response to the varying surrounding temperature is effectively amplified at the output of A3.

The above amplified response is fed over an LED/LDR opto coupler, where the LED becomes the output load of A3.

Therefore the brightness of the LED varies proportionately in response to the temperature variations, it becomes brighter with increasing temperature and vice versa.

The above illumination falls over the built in LDR of the opto, which in turn varies its resistance according to the above information from D1.

Since the LDR is fixed as the gate control resistor of the dimmer circuit consisting of R11, C5, R13, DC1 and the TR1, the voltage across TR1 starts regulating the mains AC in accordance with the fed LED/LDR response.

When the LED is bright (at higher temperatures), the LDR resistance lowers. allowing the triac to pass more current. This increases the speed of the fan, and when the LED/LDR response decreases (at lower temperatures), the speed of the fan also decreases.

A compact power supply consisting of C3, C2, Z1 supplies the required filtered DC to the IC LM324 temperature sensor configuration for the intended operations.

Idealy P1 should be adjusted such that the LED just begins glowing at about 24 degree Celsius, initiating the rotation of the fan at the minimum level.

D1 must be kept exposed well outside the enclosure so that it is able to sense the fan breeze directly.

WARNING - THE CIRCUIT IS NOT ISOLATED FROM MAINS AC...... BE VERY MUCH CAUTIONED WHILE BUILDING AND TESTING THIS CIRCUIT.

Tuesday, July 2, 2013

PIC Controlled Relay Driver

Saturday, April 13, 2013

Remote Controlled Fan Regulator Circuit Diagram

Friday, March 29, 2013

Automatic Temperature Climate Controlled Mains Fan Regulator Dimmer Circuit