Quote from: Super God on July 19, 2007, 04:21:01 PM

I've taken pictures of mine, it's all wound and everything, the collectors, bias, and controls.  Just figuring out a good oscillator plan with the tubes I'm going to order eventually (money issues)

Why not try a simple blocking oscillator design using a small torrid from a PC power supply and tap that for your open ended primaries? I recall reading that you can build 2 blocking osc and have one track the other and by adjusting the time constant of one you can create a simple frequency divider which is sync'd.

here a a couple of sites that might be interesting to review.

http://139.134.5.123/tiddler2/c0508/block.htm

http://home.att.net/~pldexnis/CTC2_how_it_works/blocking_oscillator.html

http://www.vias.org/eltransformers/lee_electronic_transformers_11_01.html

http://www.electronic-circuits-diagrams.com/psimages/powersuppliesckt6.shtml

http://www.du.edu/~etuttle/electron/elect37.htm

Take a look at the MG400Q1US41, datasheet attached. A bit large, but they should have similar lower power devices in smaller packages. I have not looked.

Rise Time (tr) 0.3 uS typ, 0.6 uS max
Turn-on Time 0.4 uS typ, 0.8 uS max
Fall Time 0.2 uS typ, 0.5 uS max
Turn-off Time 0.8 uS typ, 1.5 uS max

Bob

@Darren

I'm not sure that that response was a specific recomendation to use that exact part as the MOSFET, but just an example of a device. By the way, if you are not switching a boatload of current, switching times on even large devices can be much faster than published specs. Just take a look at the time vs voltage and current charts. On of my replicators does in fact use the MG400Q1US41 and drives them with TC4420 chips, but I have not used it myself yet.

As for the Lumex OCP-PCP116, do not sell it short so quickly. Try finding another opto-isolated chip that can accept a logic level input, amplify it, clean it up, power itself with internal regulator from a higher voltage (in case you need 24 volt operation) gate supply, and deliver a clean crisp output in excess of 100 Khz. Especially for the price!. It is a very nice chip for the application as long as it is driving small power FETs. I would not use that chip to directly drive a large FET with a lot of gate capacitance however. In the random phase pulsed mode operation that the PWM3 series runs in, propagation delay is not important. It does have very good rise and fall times, 3 times faster than similar chips, even from the same manufacturer. I used that chip because it was the best choice for the application in the PWM3 series.

Now for the rotational version, the PWM3 series board is not used. For that I suggest a more appropriate driver. Like the TC4420, or the TI chips UC3710, UCC37322, ect.