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Electronics Forum / Basics / July 20081N2071 diode speed
I found four 1N2071 diodes in my junk pile. Apparently the 1N2071 is an obsolete diode - Mouser doesn't carry it anymore. I looked up the datasheet for the 1N2071. It seems designed to operate at 60 Hz, but didn't find any info on the maximum speed for how quickly the diode can operate. http://www.alldatasheet.com/datasheet-pdf/pdf/102157/IRF/1N2071.html Can the diode successfully operate at up to 10 kHz? I have a sinking feeling the answer is "no". So, how quickly CAN the diodes reliably switch? 100 Hz? 400 Hz? Any ideas? Thanks, Michael > I found four 1N2071 diodes in my junk pile. Apparently the 1N2071 is > an obsolete diode - Mouser doesn't carry it anymore. [quoted text clipped - 11 lines] > > Any ideas? 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: http://www.microsemi.com/micnotes/302.pdf MIL-STD-750, Method 4031 for testing reverse recovery starting at page 100 of: http://snebulos.mit.edu/projects/reference/MIL-STD/MIL-STD-750D-Notice2.pdf There was a time when the test setup was shown on every fast recovery diode data sheet.  SignatureRegards, John Popelish > mrdarr...@gmail.com wrote: > > I found four 1N2071 diodes in my junk pile. Apparently the 1N2071 is [quoted text clipped - 40 lines] > > John Popelish Ok, thanks! Michael > I found four 1N2071 diodes in my junk pile. Apparently the 1N2071 is > an obsolete diode - Mouser doesn't carry it anymore. [quoted text clipped - 9 lines] > > So, how quickly CAN the diodes reliably switch? 100 Hz? 400 Hz? Any diode designed for AC line power switching is probably good for 400Hz but don't bet on anything much above that. 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 > I found four 1N2071 diodes in my junk pile. Apparently the 1N2071 is > an obsolete diode - Mouser doesn't carry it anymore. [quoted text clipped - 9 lines] > > So, how quickly CAN the diodes reliably switch? 100 Hz? 400 Hz? 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 > Any ideas? > > Thanks, > > Michael >> I found four 1N2071 diodes in my junk pile. Apparently the 1N2071 is >> an obsolete diode - Mouser doesn't carry it anymore. [quoted text clipped - 19 lines] > since they are in switching supplies, they will be good at higher > frequencies. 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. > > I found four 1N2071 diodes in my junk pile. Apparently the 1N2071 is > > an obsolete diode - Mouser doesn't carry it anymore. [quoted text clipped - 27 lines] > > > Michael 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 >I found four 1N2071 diodes in my junk pile. Apparently the 1N2071 is >an obsolete diode - Mouser doesn't carry it anymore. [quoted text clipped - 15 lines] > >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 |
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