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: hello , leith here i am probably asking a question which has been asked
: before but i cant find any info .Could someone please help ? I am wanting
: to build a 12v battery powered coil using a bosch gt40 oil filled ignition
: coil , i have built a 555 signal gen and have made a MMC using .01uF 3KV
: (x13) and am needing some advice on how to wire up signal gen to ignition
: coil/MMC/spark gap/tesla coil can someone please point me to a clear
: diagram of how to wire this configuration .thanks for your help .leith
:
:
: Hello Leith,
:
: You need to drive a power transistor with the 555 timer. A power
: transistor is required to do the actual current switching for the ignition
: coil since the 555 cannot directly handle the primary current. A more
: subtle problem is that the ignition coil must either be capable of
: charging your Tesla Coil tank cap on EACH pulse of primary current, OR you
: will need to add a high voltage rectifier on the output of your coil so
: that you can charge the tank cap over multiple primary cycles. Either
: option has tradeoffs, but let's at least find some circuits that will
: drive your coil.
:
: There are a number of circuits on the web for driving ignition coils from
: a low voltage supply. One of the more popular and simplest circuits is
: here: http://www.geocities.com/CapeCanaveral/Lab/5322/coildrv.htm
:
: The main problem with this circuit is that, when the transistor turns off,
: a large voltage spike is generated by the inductance of the ignition coil
: primary. However, this can be easily fixed with some minor changes:
: 1. Use a higher voltage (500 volts or higher) NPN, IGBT, or MOSFET power
: transistor.
: 2. Connect a 150-300 volt MOV across the transistor to prevent the
: transistor from being overvolted during turn-off. Another option is to
: connect a diode across the ignition coil primary (arrow
: "pointing" to the +12 supply).
: Here's an example: http://members.misty.com/don/igcoilhv.html
:
: Also, here's an example of a slightly different circuit used to power a
: small Tesla Coil:
: http://www.rmcybernetics.com/projects/DIY_Devices/homemade_tesla_coil.htm
:
: Here's a little bit different approach that uses a high voltage full-wave
: rectifier bridge on the HV side of the ignition coil.
:
: http://www.rmcybernetics.com/projects/DIY_Devices/homemade_power_pulse_generator.htm
:
: WARNING: Any time you combine a DC source and capacitors, you run an
: increased shock hazard - charged capacitors can be quite dangerous, even
: lethal, especially if they store more than 2-3 joules of energy.
:
: Good luck and best regards,
:
: Bert
:
:
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