Power Supply Freds, Hexfreds, Ultrasofts, Ultrafasts and Fast Recovery

[pinkmouse]

I have had good results with Onsemi's MBR10100 Schottkys

[mbroker]

Originally posted by Circlotron
With some exceptions, they begin to get rare above 100v. (Infineon does have a 600v 6A Silicon Carbide schottky but the forward voltage drop is about 2.8 volts or so)

Could one not series two or more for increased voltage? Thinking class A bits of a bigger poweramp.

Mark Broker

[icceman]

Difference between normal and schottky bridge rectifier:



Normal rectifier


Schottky rectifier




Aleph 5 PSU using schottky rectifier

[Circlotron]

Originally posted by mbroker


Could one not series two or more for increased voltage? Thinking class A bits of a bigger poweramp.

Mark Broker

Can't see why not. As you hit their reverse voltage limit they start to get very leaky so I expect if you have two or more in series then the first one to hit it's limit would stop and the others would then get their fair share. You can definitely do this with avalanche protected diodes like BYV26C for instance. 30 or 40 threaded in series through the length of an old ic tube works well for rectifying the output of an ignition coil. I haven't tried it with zeners though but it should be reasonable. Otherwise, put an equal value resistor say 4k7 across each to balance the reverse voltages. I have since read that IR have some 150v 80 A (dual?) TO-247 schottky's.

[boyelroy]

Iceman--

Now THAT is a power supply...which specific Schottkys did you use? They look like they might be TO-220/TO-247 packages with some serious heatsinks attached.

In any case, I wanna build one for my preamp/headamp!

[mbroker]

Originally posted by Circlotron
30 or 40 threaded in series through the length of an old ic tube works well for rectifying the output of an ignition coil. I haven't tried it with zeners though but it should be reasonable. Otherwise, put an equal value resistor say 4k7 across each to balance the reverse voltages.

I prefer to use 1N4007 for HV work, especially if you want to full-wave rectify a HV transformer. Hard to beat $.02 ea

I, too, was thinking a higher-value resistor in series would probably help balancing and increase diode life. But I was thinking 100k or more so as not to waste too much power, particularly for a higher voltage, low current supply.

Regards,

Mark Broker

[icceman]

Originally posted by boyelroy
Iceman--

Now THAT is a power supply...which specific Schottkys did you use? They look like they might be TO-220/TO-247 packages with some serious heatsinks attached.

In any case, I wanna build one for my preamp/headamp!

The Schottkys are 43CTQ100 (40A,100V,TO-220) from IR.

[jwb]

What was the "normal" rectifier in your top trace? 1N4004? Or a controlled recovery type?

[icceman]

It's from a standard bridge module (forgotten the part no).

[Nelson Pass]

Originally posted by boyelroy
Are these the type you use in your preamp designs?

Naaaaw. I won't let Wayne spend that much money on 100V
Schottkys. He uses soft/fast recovery types most of the time.