My application is to build a reusable Fuel Injector cleaner / tester, as described here http://hackaweek.com/hacks/building-an-electronic-fuel-injector-tester/
What I’m doing seems like a reasonably well discussed circuit, however this issue has me stumped.
I’m trying to trigger an astable circuit from a one-shot monostable circuit, holding a pulse for a period of time (adjustable). If I isolate each timer, they work as expected. When I trigger the astable circuit from the monostable circuit, I get one pulse cycle and no further.
Unfortunately I don’t have an oscilloscope (not sure I need one), measuring the voltage at the output of U1, starts at 11.2v until 1 cycle is complete, then drops to ~2.4v (Astable output pin hits 0v) until the monostable timer completes.
I’ve chosen the timer values to try best represent fuel injector timings:
I’m using the 7555, given it’s a more modern implementation and seems more “robust”.
There could be a better way of doing this, electronics isn’t my strong suit and I’m open to recommendations. One solution I pondered was to add a transistor between the two circuits.
Apologies, the schematic isn’t very well presented, I used the best tool I had at my disposal.
Mod: lightened your image.E
What I’m doing seems like a reasonably well discussed circuit, however this issue has me stumped.
I’m trying to trigger an astable circuit from a one-shot monostable circuit, holding a pulse for a period of time (adjustable). If I isolate each timer, they work as expected. When I trigger the astable circuit from the monostable circuit, I get one pulse cycle and no further.
Unfortunately I don’t have an oscilloscope (not sure I need one), measuring the voltage at the output of U1, starts at 11.2v until 1 cycle is complete, then drops to ~2.4v (Astable output pin hits 0v) until the monostable timer completes.
I’ve chosen the timer values to try best represent fuel injector timings:
- Mono 1s & 5s
- Astable 1s/1s & 1mS/1mS
I’m using the 7555, given it’s a more modern implementation and seems more “robust”.
There could be a better way of doing this, electronics isn’t my strong suit and I’m open to recommendations. One solution I pondered was to add a transistor between the two circuits.
Apologies, the schematic isn’t very well presented, I used the best tool I had at my disposal.
Mod: lightened your image.E