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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



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

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



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)


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.

Actually you can not bother to design a multiplexer using logic gates because it has many special IC which functioned for a multiplexer.

One of the TTL ICs from the family that you can use to fulfill the function of a multiplexer is IC 74 251. At the IC there are 8 input channels and 3-bit selector and the other lane as a control reset and inverting output. As a note if you are using TTL ICs for your electronic circuit, the voltage supply that is allowed a maximum of 5 volts. So you can be more familiar with the workings of this multiplexer ic, IC74251 consider the truth table below:

Author: L. Cox - Copyright: Silicon Chip Electronics

All technicians must have the same experience that the old models of aircraft generally have several common Elco its dry or down in value, mainly found in many brands of china plane. Eco is dry can cause a variety of disorders that are sometimes difficult to trace or even be able to make certain parts do not work at all, especially if used on a circuit that works at such high frequency SMPS (Switch Mode Power Supply) and the horizontal. Elco dry technicians sometimes make headaches and time consuming when you track the damage.

Many technicians get around this problem by directly replacing all existing Elko, the Elko-regardless of whether Elko is corrupt or not. It is generally quite successful. But sometimes the quality is not good substitutes Elko, so the damaged aircraft back after use for some time. Replace all of Elko is also a problem for yourself if the circuit is improved a lot using Elko. The use of ESR-meter proved to be the most appropriate choice to solve the above problems. We suggest that ESR-meter is a must-have tool for every technician after avo-meter.

Using ESR-meter weve made themselves at a cost of less than 50,000 rupiah we recorded a lot of advantages such as:

Note:

Does ESR it actually?Parameters are generally owned by a Elko understood by engineers is the "maximum working voltage" and "capacitance value". In the real case there are several other parameters such as the "maximum working temperature" (85 or 105 degrees C) and "ESR" (Equivalent Series Resistance).Unless the practice is capacitive in Elko also has the characteristics of "resistive" caused by a combination of resistance to the legs, internal connections, plates and electrolyte. Thus form a resistive characteristic ESR, because if it is portrayed as if such be installed in series with the capacitance of Elko.Ideally, an Elko ESR is zero, but in practice this is impossible.Elko High voltage tends to have larger ESR than the low voltage ElkoElko with small values ​​tend to have higher ESR values ​​greater than Elko.Elko 105 degrees (C) tend to have higher ESR than Elko 85 degrees (C).

What Is the ESR-meter?

ESR meter is a kind of ohm-meter that can be used to measure the amount of "resistance" of Elko. Difference if the ohm-meter using a dc current (direct current) to drive the meter, then use the ESR meter ac (alternating current) with a standard frequency 150Khz. As had been explained that ideally Elko its ESR is zero. But this is not possible in practice. Elko good quality 10uF value is close to zero or more generally.

What is the cause of ESR Elko subject to change.

Consequences of changing the value of ESR Elko

Our experience with the use of ESR meter in the aircraft repair older model (the old plane), the first one we always do is:

How to use homemade ESR meter (calibration)

Li-Ion DRIVER WITH EXTERNAL PWM DIMMING ELECTRONIC DIAGRAM

Perhaps the surround amplifier circuit below is an interesting circuit is made. For, making easy just by using the IC and electrolytic capacitor added 1 , we already can hear the strains of music with sound ( Front Left ,Right and surround Right , Left. In addition to listening to music , this amplifier is also very suitable for gamers who want good sound quality.