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.
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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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