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Here's what I need, Not sure of proper names but here goes:
I'm looking for a 12DV basic timer that keeps it's programming when the power is cut off. (could even be analog timer) and also a 12 vdc 1/4""push" solenoid, that retracts when the power is cut.
So when the truck is running, a relay will not let power to the timer or solenoid.
Shut off the truck, and the relay allows power to the timer, the timer starts the clock ticking for say 15 minutes.
The power goes from the timer to the solenoid, it pushes out.
Now this just sits there until the timer reaches set time (15 minutes).
Timer shuts down, interrupting power to the solenoid, which now pulls back (and stays there).
This does nothing on a truck re-start.. Only after the truck is shut down again, does the timer come alive again and starts the cycle again..
It sounds like a diesel shut down timer.
You turn the key off and it keeps the motor running to cool the turbo down.
If you shut down with turbo hot the oil at the turbo bearings cooks and turns to coal!
Dave ----
Ron - If I understand correctly you want a solenoid, like a throttle stop solenoid, to extend when the key is shut off and then retract in 15 minutes. Right?
If so, how accurate does the "15 minutes" have to be? And, what is the solenoid doing? Or, more specifically, how strong does it have to be?
Ok, from what I understand from your PM, Ron, I have it right. The only problem I have is what solenoid is strong enough to open the throttle. Anyway, I would use a 555 timer circuit to pull in a Bosch relay when the ignition switch turns off. Easily done with a 555, just watch for a negative-going voltage and start the timer. The timer pulls in the relay by grounding the coil circuit, the other side of which is tied to the battery. (Solid state circuits can sink about 10 times as much current as they can source, which is why you always see them on the negative side of things - like the DS-II module to the coil.). Then, after 15ish minutes (it is an analog circuit and not too precise) the timer turns off, the relay opens, and the solenoid retracts.
The problem with this is if you want to re-start within the 15 minutes. With this circuit there is nothing to turn the timer off if you turn the key on, and we need that for a safety. Hmmm, yes, I think I see a way to do that. Got it.
If using the relay as the first device, with the ignition on it will will in an "open" state not giving power to the timer or solenoid.
So in theory, even if the timer is set for, say 20 minutes, and you turn on the truck after 5 minutes, powering the ignition system will shut off the timer circuit. Correct?
Here's how I would do it. It is using a 555 timer in the monostable mode, which means that when a negative pulse is seen at the trigger the output will go high for a time determined by R1 & C1. So, we wire that to the ignition power so that when the key is turned off it creates the negative pulse. The high output of the timer goes to the coil of the Bosch relay, and the other side of the relay's coil goes to the ignition so that if the ignition is turned back on the relay will have positive voltage to both sides of the coil and won't be pulled in - the failsafe. The relay pulls in the solenoid.
Last edited by Gary Lewis; Mar 26, 2016 at 11:40 AM.
Reason: Forgot a ground
If you don't have a solenoid to push the throttle open look to late 60's early 70's v8 cars with AC.
When you turned on the AC the solenoid pushed open the throttle to up the idle RPM.
Also some used it to set idle speed and when you turned off the motor the solenoid would close the throttle lowering the RPM so the motor did not diesel.
Dave ----
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