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Author Topic: [SOLVED... Almost] ideas/help for arduino gsm remote control of engine preheater  (Read 7362 times)
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Odense, Denmark
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just tested the thing in the car and everything works..... EXCEPT that the wire that senses the flame makes the voltage dip to much for the heater to sense the flame...

the way i have done it is by optocoupler, hmm... should i just do it by voltage divider?
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upps... what happens is that the control box puts out 12V on the flamse sensor, the sensor is just a photo transistor that sits at the end of a tube that sits in the flame, so when there is a flame after 10 seks or so it will be very bright inside that tube and the voltage will drop to arround 1V

my guess is that the optocoubler i use at the input actually pulls those 12V to ground hence makes the heater think there is a flame before there should and that makes the heater shut down at once...

not that i'm a total noob but what would the best way be to sense those 12V without making the voltage change to much?
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any genious that can tell what is the best way to messure without affecting the voltage ?

optocoupler is out because that one for sure affects the voltage enough for the heater to think there is a flame, voltage comes to close to 1V
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*bump*
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Use an opamp as a buffer and then read that, this way you have a very high impedance load and it will not affect the voltage
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