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Thanks for your reply. We have a USB-powered current loop interface for the Teletypes; that's your design, I assume? If so, cool. I figured it would be controv

by kens 8y ago

Thanks for your reply. We have a USB-powered current loop interface for the Teletypes; that's your design, I assume? If so, cool. I figured it would be controversial to call the power supply a switching power supply, but I haven't seen a solid reason yet to exclude it. Putting a transformer upstream of the switching makes it an on-line power supply as opposed to an off-line power supply (dumb names, but I didn't make them). I'm not sure how you're distinguishing between a "switching voltage regulator" and a "switching power supply".

Animats 8y ago
Oh, did you get the ones Steve Garrison makes up? That's my design. Or did someone else get the files off Github and make some? A switching power supply has actual power conversion driven by the switching. See The Art of Electronics, by Horowitz and Hill, 3rd ed., section 9.6. That thyratron circuit is a lamp dimmer circuit repurposed as a voltage regulator. Like SCRs and triacs, a thyratron is a switch you can't turn off. You have to wait for the input power to turn off. Usually that's the next cycle of AC. Because you can't turn off the power, you can't generate inductive spikes, so you can't pull the basic trick that make a switching power supply go. There were some real switchers in the tube era. The most common one was used to generate the high voltage (10KV-20KV) for CRTs. Those used the horizontal oscillator, running at 15KHz and yanking the beam back at the end of each scan line, as a spike generator. That approach used a real vacuum tube, not a cold-cathode gas filled tube like a thyratron. So those were high voltage but low current devices. Switching power supplies with serious current output had to wait for a component that could turn off fast under load. Power MOSFETS, etc. If you could do that with a thyratron, we would have had switching power supplies by 1950.
- CamperBob2 8y ago
  Because you can't turn off the power, you can't generate inductive spikes, so you can't pull the basic trick that make a switching power supply go So what's a charge pump? Chopped liver?

by kens 8y ago

Animats 8y ago

Oh, did you get the ones Steve Garrison makes up? That's my design. Or did someone else get the files off Github and make some? A switching power supply has actual power conversion driven by the switching. See The Art of Electronics, by Horowitz and Hill, 3rd ed., section 9.6. That thyratron circuit is a lamp dimmer circuit repurposed as a voltage regulator. Like SCRs and triacs, a thyratron is a switch you can't turn off. You have to wait for the input power to turn off. Usually that's the next cycle of AC. Because you can't turn off the power, you can't generate inductive spikes, so you can't pull the basic trick that make a switching power supply go. There were some real switchers in the tube era. The most common one was used to generate the high voltage (10KV-20KV) for CRTs. Those used the horizontal oscillator, running at 15KHz and yanking the beam back at the end of each scan line, as a spike generator. That approach used a real vacuum tube, not a cold-cathode gas filled tube like a thyratron. So those were high voltage but low current devices. Switching power supplies with serious current output had to wait for a component that could turn off fast under load. Power MOSFETS, etc. If you could do that with a thyratron, we would have had switching power supplies by 1950.

CamperBob2 8y ago
Because you can't turn off the power, you can't generate inductive spikes, so you can't pull the basic trick that make a switching power supply go So what's a charge pump? Chopped liver?