# Divide by 6 frequency divider

Discussion in 'General Electronics Discussion' started by Andrew.miles, Aug 3, 2012.

1. ### Andrew.miles

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Aug 3, 2012
Hi all. I'm new here, but looking for a bit of advise. I have a Smiths rev counter that is designed to work with a petrol engine ignition system, putting out 2 pulses per revolution of the engine. I'm trying to get it to work on a diesel engine, by driving it from the rev counter terminal on the alternator. The only problem with this, is the alternator is a 12 pole unit, so puts out 6 pulses per revolution, plus it is driven at twice engine speed. I've decided the easiest way to get it to work would be to build a divide by 6 frequency divider circuit. I've found a generic diagram for the circuit here http://www.ecelab.com/circuit-frequency-divider.jpg However I'm not sure how to configure it to divide by 6. Any ideas on this would be appreciated. I also presume that I would then need to use the circuit to trigger a transistor, as I think the current drawn by the rev counter (An inductive type) would be higher than that 555 timer could supply. I'm not sure on connecting these up, though from what I can see, the output from the frequency divider would connect to the base, +12v to the collector and the emitter connected to the rev counter.
Any thoughts on this problem would be greatly appreciated.
Thanks
Andrew

2. ### Andrew.miles

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Aug 3, 2012
Actually, that said, I'm sure the rev counter has a 6 cylinder setting. If I were to use that, I would only need a divide by 4 circuit, so could use 2 divide by 2 circuits, the output of one being the input to the second one. Even so, I'm not sure exactly which components I should be using to make a divide by 2 circuit, as the first diagram shows a range of values.
Thanks
Andrew

3. ### Andrew.miles

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Aug 3, 2012
Ok, done some more research, thats not going to work...
I'm now planning on using a hall effect sensor and a magnet on the crank. Again though, I'm not sure on the circuitry. I presume I'd need the hall effect sensor to operate a transistor. Any help will be greatly appreciated.
Andrew

4. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
The best way to divide by 6 is to do it digitally.

There are many ways to do it. One is to use a 4017 and set the 7th output to reset the chip.

There are other ways too. Google "divide by 6 schematic" and you'll probably find more options.