# Inductive kick as a pulsed power source?

#### nitouken

Joined Dec 17, 2007
4
Can it be done? Contemplating a homebrew coilgun as a birthday present for a friend. Pulse rated caps in the appropriate voltages are way outside my budget. How would I calculate the voltage of the kick, so that I can have properly rated SCRs?

#### mrmeval

Joined Jun 30, 2006
833
There are a dozen coil gun sites on the web with instructions. You enter the realm of spooky with high power magnetic fields.

#### nitouken

Joined Dec 17, 2007
4
Yah, I was rather getting that idea. Moving from simple audio and timing stuff to bizarre high voltage realms is weird. Most of the Gauss gun sites I came across want you to use HV pulse caps, though. I will have to do more research.

#### cheddy

Joined Oct 19, 2007
87
I am pretty sure you can use an ignition coil salvaged from a car to generate tens of thousands of volts of electricity in short bursts with relative ease.

#### Mrwassman

Joined Jun 19, 2007
2
^ very true.

~12V in, ground controlled. A car at idle needs ~15Kv and the coils usually have no issue producing up to 40Kv for high load/resistance situations.

Kv to Ms output has proven to be somewhat proportional. I.E. 15Kv @ idle yields a 4ms spark after going thru all of the secondary circuit and and overcoming high combustion chamber temperatures/pressures. At 40kv it would only yield a 1ms spark. A longer coil saturation could help if you need a longer lasting spark.

#### thingmaker3

Joined May 16, 2005
5,084
Inductive kick will indeed generate high voltage. Nice little arcs! I don't know about high power though... If you put a load on your kick, won't it reduce dI and increase dt?

#### nitouken

Joined Dec 17, 2007
4
While 15 kV sounds very nice in theory... there is no way on earth that I can afford an SCR rated for 15 kV, no matter what the current. I was more hoping for some hint towards inductor construction. I am probably thinking something in the area of 400 - 600 V. I am still very much in the design phase, so I am open minded, but I am not talking about anything other than a cool toy, really.

#### frogy

Joined Dec 24, 2007
11
With an ignition coil circuit, you control the 12v input to the coil which controls the 15 Kv output... So really you only need a relay\transistor\etc... that can switch 12v

If you use a relay, make sure you use a solid-state relay so there is no mechanical bounce...

Triggering could be handled by a monostable 555 timer to prevent trigger bounce

I need a ~600V SCR for a camera flash ignition circuit for pyrotechnics... I have a good camera flash circuit made, and a decent RC circuit, but I need to find an SCR to switch the 330-500V output of the flash cap...