auto advance

[c_Moore]

Hi everyone,
I am the process of designing a autoadvance for a CD ignition modual that I made.Im using a 12F675 ,and a single hall sensor to trigger the spark on the engine.I'm not real sure how to do this.any suggestions would be greatly appreciated. Thanks Charlie

[mister_e]

Hi c_Moore, for sure i cam help but, i don't understand what your project is suppose to do. Tell me more about. What go in and what you want as output.

regards

[c_Moore]

Hi Mister E thanks for the reply.What I want to so is I have a hall sensor to sense input pulses.I set the static timint at 30 dgrees.What I need the PIC to do is at start up and idle delay enough to make the sparkplug fire at 4 degrees. as the RPM increases reduce the delay in proportion to the RPM until 7500 and above.Then have no dalay .To make the plug fire at all It takes a low pulse. Thanks for the help.Have a great day


BTW: the engine this setup is on is a converted weedwacker I converted it to a model airplane engine.

[mister_e]

Hi c_moore,
of course you can use Hall effect sensor for your task. Or, as i saw in the past, take a wire (18 AWG & less) and make few turns over the spark plug wire(like a coil). Connect your wire to an opamp or voltage comparator input via capacitor and read it. This solution was use in some old remote starter and few RPM.

regards

[c_Moore]

HI Steve,
That a good idea.I would of never thought of that.Could I do something like this:read the voltage input and use a A/D converter on the chip .As the voltage increased decrease the delay and as the voltage dropes increase it.Does this sound Practical? Thanks Charlie

[mister_e]

hum... as you'll see the output signal will be pulsed so should read frequency. But if you want, you can convert it to voltage... for sure. An addition RC circuit + opamp as buffer will do so. Now you need 1 double opamp(747,tlo72,tlo82,Ne5532....) to do the *preamp* + frequency to voltage conversion. or there's a often use frequency to voltage converter on the market called LM2917. see datasheet
http://www.national.com/ds/LM/LM2907.pdf

[c_Moore]

HI Steve,
Thanks for the fast reply.I will check into the part numbers and see what I can come up with. Reguards Charlie