According to Wikipedia.org, A tachometer is an instrument that measures the rotation speed of a shaft or disk, as in a motor or other machine. Below schematic shows a simple design of Car Tachometer Circuit Diagram using NE555 timer. The NE555 consists of two voltage comparators, a bistable flip-flop, a discharge transistor, and a resistor divider network.
Tachometer Circuit Description
The timer receives pulses from the distributor points. Meter M receives a calibrated current thru R6 when the timer output is high. After time-out, the meter receives no current for that part of the duty cycle. Integration of the variable duty cycle by the meter movement provides a visible indication of engine speed.
Tachometer Circuit Parts List
| Resistors R1 ____ 1K R2 ____ 5K R3 ____ 5K R4 ____ 50K R5 ____ 5K R6 ____ 200K R7 ____ 15 Diodes |
Capacitors C1 ____ 0.1uF C2 ____ 0.1uF C3 ____ 10uF Other |
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6 comments for this entry ↓
1 FranklinPV // Oct 30, 2010 at 7:21 am
The schematic shows a 50mA full scale meter, but your parts list says 10mA. Is it supposed to be 50mA? Thanks.
2 schematic // Nov 3, 2010 at 5:19 am
yes it supposed to be 50mA, thanks
3 Sid // Nov 26, 2010 at 10:46 pm
What type of coil is used and give me some description. plz
4 missy // Mar 7, 2011 at 10:29 pm
what is distributor points?
5 Maran // Mar 8, 2011 at 3:15 pm
I don’t understand the ignition coil part and connection. And also the distributor points connection. Thanks for your help.
6 zver // Apr 6, 2011 at 9:48 pm
Does tachomether needs calibration, and how do you calibrate it ?
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