| Electronics > Beginners |
| Common emitter push-pull? |
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| JS:
--- Quote from: Hero999 on June 22, 2018, 11:53:41 pm ---Just thinking Q3 will be dissipating a fair amount of power. I'm not sure if it's a good idea to drop that kind of voltage and current, even at 50% duty cycle, so a collector resistor is a good idea: I'd go with 22k. Another option is to add 100V zener diode and biasing resistor, so Q3 no longer needs to drop such a high voltage. --- End quote --- Meh.. You need to drop that energy somewhere, expend your money in a zenner or a bigger tranny, I'd go for the single part. JS |
| T3sl4co1l:
OP hasn't mentioned how much current or capacitance drive is required, so it's impossible to say how much drive the transistors also need. Tim |
| JS:
--- Quote from: T3sl4co1l on June 23, 2018, 01:16:06 am ---OP hasn't mentioned how much current or capacitance drive is required, so it's impossible to say how much drive the transistors also need. Tim --- End quote --- He used 1k load in the schematics, looks like a lot, 20W to the load but who knows... JS |
| TheBaconWizard:
Some seriously fantastic and detailed help here, MANY thanks everyone. I have work to do! |
| Zero999:
--- Quote from: JS on June 23, 2018, 12:22:31 am --- --- Quote from: Hero999 on June 22, 2018, 11:53:41 pm ---Just thinking Q3 will be dissipating a fair amount of power. I'm not sure if it's a good idea to drop that kind of voltage and current, even at 50% duty cycle, so a collector resistor is a good idea: I'd go with 22k. Another option is to add 100V zener diode and biasing resistor, so Q3 no longer needs to drop such a high voltage. --- End quote --- Meh.. You need to drop that energy somewhere, expend your money in a zenner or a bigger tranny, I'd go for the single part. JS --- End quote --- I suppose the zener could be replaced with a cheap resistor, but it would still require a high voltage transistor. --- Quote from: JS on June 23, 2018, 03:07:01 am --- --- Quote from: T3sl4co1l on June 23, 2018, 01:16:06 am ---OP hasn't mentioned how much current or capacitance drive is required, so it's impossible to say how much drive the transistors also need. Tim --- End quote --- He used 1k load in the schematics, looks like a lot, 20W to the load but who knows... JS --- End quote --- Are you referring to my schematics? I guessed and a 1k load would not dissipate 20W, but 4.9W, since it's capacitively coupled it would get 70V, not 140V. |
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