ParkingLotLust
Member
All the examples Ive found for 555's show how to source current (turn on an LED, etc). How can I get it to sink current? Ideally, my circuit is going to sink an unknown amount of mA (shouldnt be very high, but 555's are cheap anyways), from 5v (signal is pulled to 5v inside PCM) down to GND @ 57Hz, running off 12v. If someone would toss this together real quick, that would be nice
But just telling me how to sink current would work just as well.
EDIT and ha ha to everyone who says "this sounds like homework". Im using it to emulate a Flex-Fuel sensor on an '00 Ford Ranger:
EDIT and ha ha to everyone who says "this sounds like homework". Im using it to emulate a Flex-Fuel sensor on an '00 Ford Ranger:
The fuel sensor signal is a square-wave voltage signal. The signal varies in both frequency and pulse width:
The frequency of the signal indicates the ethanol percentage. The output frequency is linear with respect to the percentage of ethanol content in the fuel. The PCM provides an internal pull-up to five volts on the signal circuit, and the fuel sensor pulls the 5 volts to ground in pulses. The normal range of operating frequency is between 50 and 150 Hertz:
50 Hertz indicates 0% ethanol
150 Hertz indicates 100% ethanol