Hi, i wanted see if someone could help me make a diagram on a rpm simulator for a project im working on. I have a picture of one i got from a buddy but is no longer working and needed to see if i can make one myself thanks for any help

 

Looks like a simple Astable 555 circuit, with a zener diode supply regulator..
Reverse engineer the circuit by measuring the resistors from each pin, plenty circuits online.

It's probably centered around 50Hz ( 30 to 150Hz)

 

This is 2 units i built. One is for testing Tachos & speedos. The other for testing Injectors & Ign coils. Built them back when i was working as a Mechanic.

 

Sweet ,Thank you guys for your quick replies i will give both Suggestions a try and hopefully it works thanks again

 

Methinks the LED is shown wrong way up in the Ign Pulse Simulator schematic in post #3.

 

OOPS.