zvs driver questions / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

zvs driver questions

Move Thread

LAN_403

alf

Sat Jul 02 2011, 10:28AM

Registered Member #3925 Joined: Fri Jun 03 2011, 10:50AM
Location:
Posts: 121

hey,

i have finally decided to build the zvs driver, and naturally i have a few questions -

the 47-200uH inductor; could i use barrys aircore inductor simulator, to work out how many turns etc. i will need to make the suitable inductor?

and, i intend to operate the circuit at 36v input, do i need to change the values of anything in the circuit because of this?
and could i use a mosfet such as the irl540n?

because, since this circuit is very efficient, the power dissipation of the mosfets doesnt have to be very high, and the irl540n is rated at 100v, 36A, 140W, i know it says to multiply the supply voltage by 4 to find the necessary rated voltage but... is this necassary?

if it is necessary, i could always use the irf640n which is rated at 200v 18A, 150w

thanks. Alf.

Forty

Sat Jul 02 2011, 03:46PM

Registered Member #3888 Joined: Sun May 15 2011, 09:50PM
Location: Erie, PA
Posts: 649

you could use the inductor sim, or various toroid inductor sims on the web, but i'd just wing it and wrap 20-40 turns of thick wire on a toroid.
at 36v input i'd say use the irf640n's. the mosfets really do see quite an increased voltage compared to the input. i've been shocked by the heatsinks at only a 12v input.
as for changing other components, use the highest wattage 12 or 15v zeners you have, and you might need to up the resistance value on the 470 ohm power resistors.
a better way would probably be to separate the power supplies for the oscillator side and primary side.
use a 12v supply for the oscillator side and use whatever you want on the primary.

alf

Sun Jul 03 2011, 10:21AM

Registered Member #3925 Joined: Fri Jun 03 2011, 10:50AM
Location:
Posts: 121

Forty wrote ...

you could use the inductor sim, or various toroid inductor sims on the web, but i'd just wing it and wrap 20-40 turns of thick wire on a toroid.
at 36v input i'd say use the irf640n's. the mosfets really do see quite an increased voltage compared to the input. i've been shocked by the heatsinks at only a 12v input.
as for changing other components, use the highest wattage 12 or 15v zeners you have, and you might need to up the resistance value on the 470 ohm power resistors.
a better way would probably be to separate the power supplies for the oscillator side and primary side.
use a 12v supply for the oscillator side and use whatever you want on the primary.

hey,

wow maybe the 4 times rule aint enough then?
although it may be surprisingly low voltage, since its ac, i can feel 12v ac quite easily, but not 30v dc...
try touching a 12v ac supply, see if you feel anything :D
hmm dyou think those transistors would work okay? cuz their resistance is 150mohm.
i dont have any zeners of that voltage, so what wattage ones should i buy?
and allright ill change the resistances :)

umm how would i go about seperating the oscillator from the main circuit? :D

thanks. Alf.

Forty

Sun Jul 03 2011, 03:57PM

Registered Member #3888 Joined: Sun May 15 2011, 09:50PM
Location: Erie, PA
Posts: 649

here's uzzor's own thread about separating the supplies. it's pretty simple.
150mohm rds on will require a large heatsink. insulate the fets from the sink so that you can touch the sink to see how hot it's getting after a couple seconds. if it heats up way too fast (be careful) then you might need different mosfets. i think anything higher than 1/4 watt is alright for the zeners.
digikey would be a good place to get exactly what you want. very reasonable and fast shipping for orders under 8oz.

alf

Mon Jul 04 2011, 01:07PM

Registered Member #3925 Joined: Fri Jun 03 2011, 10:50AM
Location:
Posts: 121

Forty wrote ...

here's uzzor's own thread about separating the supplies. it's pretty simple.
150mohm rds on will require a large heatsink. insulate the fets from the sink so that you can touch the sink to see how hot it's getting after a couple seconds. if it heats up way too fast (be careful) then you might need different mosfets. i think anything higher than 1/4 watt is alright for the zeners.
digikey would be a good place to get exactly what you want. very reasonable and fast shipping for orders under 8oz.

hey,

yeahh it is pretty simple! :D
oh right, hmm maybe i will look for ones under errr... 100mohm?
hmm i dont mind electric shocks :D lol,
ah ok, cool.

so if i seperate the supplies, and power the oscillator with 12v, and the transformer at 36v,
will i need the transistors to be rated at 4x12v, or 4x36v?
and finally, do i need to change the circuit, as you said to, if i operate the oscillator seperately at 12v?
for e.g. do i need to use resistors with higher resistance than the 470R resistors? like you said to do.

thanks again :D. Alf.

Forty

Mon Jul 04 2011, 02:55PM

Registered Member #3888 Joined: Sun May 15 2011, 09:50PM
Location: Erie, PA
Posts: 649

you wouldn't have to change anything in the circuit.
the mosfets would see the 36v though

alf

Mon Jul 04 2011, 06:21PM

Registered Member #3925 Joined: Fri Jun 03 2011, 10:50AM
Location:
Posts: 121

Forty wrote ...

you wouldn't have to change anything in the circuit.
the mosfets would see the 36v though

hey,

awesome!,
okay :)

so im gonna rewind a MOT, to power the circuit, and it will draw around 15a at 36v i guess.
it is gonna need some fucking massive capacitor to smooth the rectified dc right?
or maybe a mere 2v ripple is asking too much :O, i wouldnt want the arc humming at 50hz too much though :D lol

btw, i have been using a microwave oven transformer, operating at 50v, from the variac, to reform the new 400v capacitors i bought for my coil gun, and i have been using a rectifier to rectify the 400v output from the MOT, and it seems the rectifier is only rated at 100v, i may have been using it for rectifying over 600v actually :O
awesome rectifier lol

thanks. Alf.

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob