spark retard unit for car

[pinout]

Re: spark retard unit help

Isn't this really the ideal project for a microcontroller?
You will have control over the delay at any frequency, which is effectively the ignition map of car ignition management unit.

 

[dope40]

Re: spark retard unit help

I dont know how to use PIC to do that if you could give me an example.....?:???: ,, i supose i can delay it but how can i output the same analog signal that its in the input .. i supose i have to use ADC for the input , but for the output ?

 

[BradtheRad]

The delay must be longer for slower rpm, and shorter for high rpm. This is not obvious to achieve.

In the spirit of experimentation...

I assembled a simulation which illustrates a possible way to achieve the 10-degree delay.

1) The TDC pulse is fed to a frequency-to-voltage converter. This consists of a 555 configured as a one-shot, followed by an averaging capacitor.

2) The output is applied to a capacitor (ramp capacitor). The capacitor charges faster in proportion to engine rpm.

3) When it charges to a particular volt level, the comparator triggers. It triggers sooner when engine rpm is higher.

4) the ramp capacitor is discharged.



The scope traces show:
1) the TDC pulse (I chose 1% duty cycle, not knowing how long it lasts).
2) output from the 555 IC.
3) volt level on C3 (F-to-V capacitor).
4) volt level on C4 (ramp capacitor).
5) comparator output.

It will need a lot of adjusting in order to make it operate properly.

 

[pinout]

Re: spark retard unit help

I haven't got an example but look at something like the Arduino which has a great user support forum to help newbies.
You buy a board (Uno is oldest and cheapest) but it comes with the free online compiler which is tailored towards beginners.
You will probably need a more powerful board (faster), but the code is basically the same.