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Post by Deleted on May 12, 2009 19:29:24 GMT -8
I was wondering if I could put a voltage divider at the positive input to the coil in order to reduce the coil output voltage. I am trying to keep small dogs out of a fish pond and I would like to try a lower volage to start with if possible and if it would work. Would half the voltage get their attention?
Thanks. I don't know when you will be able to answer this. I hope you are feeling better.
steviejaeye
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Post by lamazoid on May 13, 2009 11:35:38 GMT -8
You can adjust oscillator duty cycle to do this. This is done easily with 555 based coil drivers .
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Post by Deleted on May 14, 2009 14:46:34 GMT -8
Thank you for your reply. I have looked at some circuts online and I think I could integrate one into this circuit. Maybe you could enlighten me. Does a standard auto ignition coil have any limitation as to input voltage? If the coil is now seeing +12 volts and putting out 25,000 volts, would it not put out 12,000 volts with a 6 volt input? What is the advantage of the duty cycle controlled coil? Unfortunately I am not so brilliant in electronics. Thank you.
Steve
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Post by lamazoid on May 14, 2009 21:15:40 GMT -8
Input voltage is not so important. The main thing that controls high voltage of ignition coil is TIME of charge and discharge phases. Controlling this time of charge (duty cycle) from 1% to 50% you will get minimum to maximum voltage control. So, if your driver gives 24,000 volts from 12 volts with 50% duty, it will put out 12,000 volts with 25% duty, from the same 12 volts ! Yep, that's very simple  |
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Post by Deleted on Jul 28, 2009 15:39:31 GMT -8
You want to say reducing the frequency of the oscillator?
Thanks!
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Post by lamazoid on Jul 29, 2009 1:15:26 GMT -8
No. the frequency remains constant, because the PERIOD of oscillation is not changed.
For example , 10 KHz and 50% duty cycle means that transistor is on for 50 us (microsecond) and other 50us of the period it is off. For flyback type of circuits (includes ignition coil circuits) this results into MAXIMUM voltage output. When down the duty (say, "ON" for 25us and "OFF" for 75us) you will get only half of that voltage... And so on.
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Post by Deleted on Jul 29, 2009 2:05:50 GMT -8
OHHHH! Now I understand, thank you very much!  --This is very simple of obtaining with a 555-- |
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