Looking for a High-voltage power supply

Discussion in 'General Electronics Chat' started by Sami Alawadhi, Oct 12, 2015.

  1. Sami Alawadhi

    Thread Starter New Member

    Oct 5, 2015
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    We are trying to build a spark ignition circuit and we were interested in the capacative discharge circuit. Our switching device is a monostable NE555 timer circuit for purpose of regulating time and our ignition coil steps up the voltage to 20 kV to ignite the spark plug. Does anyone recommend a good high-voltage power supply to charge the capacitor? We were considering a 450-V power supply.
    Here's a link for a capacitive discharge circuit. It has the schematic: http://www.daytona-twintec.com/tech_ignition.html
    The PDF and schematic for our NE555 timer is attached.
     
  2. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    I put 'cd ignition schematic' (without quotes) into Yahoo and got over 100 schematics.

    ak
     
  3. Dodgydave

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    Jun 22, 2012
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  4. crutschow

    Expert

    Mar 14, 2008
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    What power source do you want to use to generate the 450Vdc?
    What's your budget?
     
  5. Sami Alawadhi

    Thread Starter New Member

    Oct 5, 2015
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    no more than $250.
     
  6. crutschow

    Expert

    Mar 14, 2008
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    The cheapest would likely be to get a small transformer with about a 320V output (such as this) and then full-wave rectify that with a bridge and filter to get 450Vdc.
    The device I referenced also has a couple of 6.3V windings which you can use in series to add or subtract up to 12.6V AC from the 320V output if you want to tweak the output voltage. It also has a 300V tap.

    Does the voltage need tight regulation?

    What is the maximum pulse rate of your circuit?
     
  7. ian field

    Distinguished Member

    Oct 27, 2012
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    For that sort of budget; it might be just as easy to buy a CDI unit and hack the intermediate voltage without using the trigger/SCR/capacitor discharge bit.

    The inverters usually produce somewhere in the region of 350 - 400V, but can probably be tweaked to get the required voltage.

    A very important point: do a bit of research and make sure the "best candidate" isn't potted before parting with the money.
     
  8. crutschow

    Expert

    Mar 14, 2008
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    But those usually require a 12V dc input when also has to be generated/provided.
     
  9. ian field

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    Oct 27, 2012
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    There was nothing in the original post to suggest that the energy source was to be magicked out of thin air - in fact the link was to an explanation of automotive ignition systems, although 12V supply wasn't specifically mentioned, it seemed a reasonable assumption in light of the few facts supplied.
     
  10. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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  11. recklessrog

    Member

    May 23, 2013
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    Go to the "information unlimited" web site and download the schematic for a universal capacitance discharge ignition (CDI) driver" That one will blow your socks off! Up to 50-70Kv depending on the ignition coil you use, and it's adjustable. I built one using the cores from an old B&W portable tv line o/p transformer.
     
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