1N2071 diode speed

Since the data sheet specifies no reverse recovery time, it is going to be pretty slow, probably up to several microseconds, depending on how high the forward current is just before the voltage reverses.

You could set up a test and measure it under some particular condition. Often, the reverse recovery time is measured right after the diode has been conducting something like its rated forward current, with the reverse current limited to somewhere between double that current to perhaps half it and a specified rate of change of current as it swings from forward to reverse. And the time it takes for the reverse current to fall to something like 1/4 or 1/10th of the peak value is measured. It doesn't take a very complicated test setup to do this.

See explanation of reverse recovery specs:

There was a time when the test setup was shown on every fast recovery diode data sheet.

Any diode designed for AC line power switching is probably good for

What fun I've had with Chinese outfits fitting 1N4004s where I'd specified UF4004s ! I imagine the remedy is not to use a part with the number 4004 in it lest they try and get clever and specify a BYxx something or other.

Graham

What are you trying to do? You say "switch" which implies some sort of logic or switching supply, but it's not completely obvious. What you need a diode for helps to determine what will be suitable.

Since you're pulling things out of the junkbox, why not find a junk computer, open up the power supply, and use the schottky power diodes on the secondary for this project? They are readily available, and since they are in switching supplies, they will be good at higher frequencies.

Michael

It's almost certainly a vanilla diffused-junction diode. Forward recovery (turn-on time) is probably in the 100 ns ballpark, and reverse recovery may extend into the microseconds, depending on the situation. So it's probrbly fine to a few KHz, but it may make recovery spikes and reverse recovery may increases losses (cause heating) at higher frequencies and currents. Capacitance will be the main problem at signal levels, but you can measure the cpacitance.

The higher voltage diffused diodes, like this one, tend to have pin-diode-like behavior, so can be slow.

John

specs:

of:

Ok, thanks!

Michael

Beware of low PIV SB rectifiers! - In a computer PSUs they are likely to be no more than 45V, some are low as 20V. On very rare occasions 90V SB rectifiers can be found in scrap monitors.

High voltage silicon carbide rectifiers are beginning to hit the market, but I've yet to find any in scrap gear.

That's a good idea, thanks.

What I'm doing: I'm going to try and build my own mini switchmode power supply, using pulses from a 555 in the kHz range to excite a self-wound, center-tapped toroidal transformer, to convert 12V pulses to +/- 24V, which must be recitified, of course.

Low power testing first, of course. ;-)

Ian: thanks for the low voltage warning, I'll look up the specs on the high-frequency diodes when I find them

Another Michael