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How to test 2N6027 (SILICON PROGRAMMABLE UNIJUNCTION)

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Ian.M:
I had a certain fondness for the Philips BRY39 which is a four lead PNPN device, with both the anode gate and cathode gate brought out to pins, suitable for use as either polarity of PUJT or as a small SCR with either anode or cathode gating.  Unfortunately its long discontinued and ludicrously expensive NOS from reliable stockists.

sdancer75:

--- Quote from: Ian.M on June 15, 2020, 08:10:09 pm ---Where did you get the 2N6027 PUJTs from?

--- End quote ---

https://www.ebay.com/itm/10PCS-2N6027-6027-TRANS-PROG-UNIJUNCT-40V-TO92-IC-TOP/172821744346?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

sdancer75:

--- Quote from: fuzzoli on June 15, 2020, 10:23:16 pm ---Last week I just received my ebay stash of 2N6027s!   I was actually stunned that they are still available!

@sdancer75, what will you be using them for?

-Frank

--- End quote ---

Hi,

From eBay too.

https://www.ebay.com/itm/10PCS-2N6027-6027-TRANS-PROG-UNIJUNCT-40V-TO92-IC-TOP/172821744346?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Ian.M:
So there's a medium chance that they are fakes, probably something else that's dirt cheap in the same TO-92 package, remarked.

Using a meter with a diode check range, with the remaining pin not connected, a PUJT should read as a diode between anode and gate, anode positive, and open circuit between gate and cathode in either direction.  It should read open between cathode and anode, with cathode positive.  As we discussed earlier, it should either read open or under 1V between anode and cathode, anode positive, depending on whether or not its triggered.   

If two unused ones fail those tests, you've got fakes.   Two pins conducting and a diode junction to a third pin suggests they may actually be JFETs.

sdancer75:

--- Quote from: Ian.M on June 16, 2020, 02:56:13 pm ---So there's a medium chance that they are fakes, probably something else that's dirt cheap in the same TO-92 package, remarked.

Using a meter with a diode check range, with the remaining pin not connected, a PUJT should read as a diode between anode and gate, anode positive, and open circuit between gate and cathode in either direction.  It should read open between cathode and anode, with cathode positive.  As we discussed earlier, it should either read open or under 1V between anode and cathode, anode positive, depending on whether or not its triggered.   

If two unused ones fail those tests, you've got fakes.   Two pins conducting and a diode junction to a third pin suggests they may actually be JFETs.

--- End quote ---

Hi,

As you can see by yourself I can read diode only when Gate (+) and Cathode (-) is connected. All other combinations are open circuit.

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