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Generate Pulse After Short Delay (Fuel Injector Tester)

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adamey

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I have a circuit that generates a continuous pulse train of pulses that are 1-5ms long (555 timer with variable duty cycle). What I want to do is have a short pulse (0.1-0.2ms) generated, and have this pulse occur sometime after my first timer goes high. I also want this delay time to be adjustable so that I can "sweep" the location of my second pulse to occur anywhere within the on time of my first timer.

The first timer circuit controls a fuel injector, turning it on and off repeatedly with varying pulse widths of 1-5ms. The second pulse feeds my LED strobe light so I can watch the spray pattern coming out of the injector. By having the delay time adjustable I can have my strobe flash occur anytime within the on time of the injector and "catch" the spray pattern at various points whenthe injector is open.

For those not familiar with automotive fuel injection, this is a very useful tool to have. For example, you can compare two injectors to see if they start flowing at the exact same time after they are opened (useful for spotting sticking injectors).


I'm using a Luxeon LED driven by one of their buckpucks, which has a TTL/CMOS compatible level input to control the LED. As mentioned, a 555 timer generates my pulse train for the injector. I just need the circuit in between to give me a delay before firing my strobe.

Oh, I forgot. The delay time should be able to be longer than the on time of the injector in case I want my strobe to fire just after the injector closes (to spot leaking or driping injectors).
 
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How do you plan to adjust the time delay? Is an regulated resistor good enough?

If that is, the this problem can be solved in many ways. Anything from 555 chip, some RC-circuits combined with windows detecors, and so forth.
I assume you may want to use another 555 to do this, but I'm not an expert on 555 chip.
 
Certainly you could use another 555 as a one-shot, triggered from the first 555, with a pot to vary the one-shot time.
 
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