digital multimeter for your car

Posted on Feb 6, 2014

digital tachometer & speedometer using seven segment display, but I failed to do it the right way. The circuits I used before were too crowded with ICs & other components. Then I managed to build the LED tachomter. Later, I got a stepper motor & used it as a speed sensor to build the LED speedometer successfully, too. The ICL7107 came to my mind.

digital multimeter for your car
Click here to download the full size of the above Circuit.

A simple, old yet reliable analog to digital converter used in digital voltmeter circuits. VOLTMETER Why not to build a voltmeter, then calibrating it to get the car speed from my stepper motor & get the RPM from my LM2917 voltage output What about adding a digital thermometer using the LM35 temperature sensor Photo paper with desried print (use two copies one over each other, in the rear one cut the yellow rectangles facing the LEDs). I prefer matte over glossy photo paper btw. I started with the main circuit (the ICL7107 voltmeter). The ICL7107 is an analog to digital converter interfaced to seven segment display. The 7660 provides the circuit with ( -5V) voltage from ( +5V ) input, you can use the 7905 for the same purpose (to get ( -5V ) from the ( +12V ). Other components are really few. using the 7805 voltage regulator, two 100nF pol. capacitors & one 470uF electrolytic capacitor. adding a rectifier diode 1N4007 to the 12V input (from the car battery) From the stepper motor I mounted to my car`s transmission in the previous post. The current generated directly from a stepper motor is AC (alternating current). So, I added a simple diode bridge to get DC (direct current) from AC using four 1N4007 rectifer diodes & a 100nF capacitor for "smoothening" the output. Adding 1. 5Mohm & 470Kohm trimmer potentiometer for calibration From the LM2917 pins No, 5&10. I made a small circuit powered with the same +5V supply. The...

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