A typo, methinks? For "ground", I think we want "collector" or "+10V supply", no?
UN 4211 Silicon NPN epitaxial planer transistor
- Thread starter audiobeginne
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A typo, methinks? For "ground", I think we want "collector" or "+10V supply", no?
It was a long day, I was a little tired. Edited.
As tarior has suggested, I agree that the ultimate test procedure is to install one of the parts and see if it works. The DMM, though it is unable to reveal whether the part is fully functional, should have revealed any short circuits, so there is negligible risk of doing any damage.
And if it turns out that the parts don't work, just throw them all away, and make a mental note to avoid random online suppliers for semiconductors. It might be worth checking octopart.com. Or, finding a substitute that is currently available from a first-tier supplier.
(I'm having a really hard time imagining why a reel of such parts would be wanted. I don't think I've ever seen a "digital" transistor fail. Then again, they've only been around for a few decades, and they aren't much used in the sorts of audio gear that I like to work on, so I might be missing a trend. Sorry, just typing out some pretty much aimless musings here...)
And if it turns out that the parts don't work, just throw them all away, and make a mental note to avoid random online suppliers for semiconductors. It might be worth checking octopart.com. Or, finding a substitute that is currently available from a first-tier supplier.
(I'm having a really hard time imagining why a reel of such parts would be wanted. I don't think I've ever seen a "digital" transistor fail. Then again, they've only been around for a few decades, and they aren't much used in the sorts of audio gear that I like to work on, so I might be missing a trend. Sorry, just typing out some pretty much aimless musings here...)
gslikker
Super Member
One could think about something like this using battery (or power supply) to test a yes/no situation and define the region where the transistor starts conducting (should be somewhere between 1.2 and 1.8 Volts on the base according one of the graphs). BTW a 0.5 or 1M resistor still would not work (too high) as the 10k internal resistor would leak away the current you would want to put in the base, leaving insufficient base voltage.
The idea would be measure the output voltage, it should quickly go from 9 Volts to some 0.5 or so at a certain voltage on the wiper of the potentiometer. Anyway, at a "base" voltage of 1 Volts it should be off (9V at collector) and at 2.5 Volts it should be on (0.5 Volts or lower at the collector)
(BTW I added the 10k resistor only because the max base voltage is not specified, after drawing it I realized it can be omitted)
The idea would be measure the output voltage, it should quickly go from 9 Volts to some 0.5 or so at a certain voltage on the wiper of the potentiometer. Anyway, at a "base" voltage of 1 Volts it should be off (9V at collector) and at 2.5 Volts it should be on (0.5 Volts or lower at the collector)
(BTW I added the 10k resistor only because the max base voltage is not specified, after drawing it I realized it can be omitted)
Not quite right. The datasheet shows 10k resistor to base, then another 10k to ground, so some of the "base" current goes through the resistor to ground. Need to calculate currents with a voltage divider, and 0.6 volts base to emitter voltage to get right base current. It is the main reason transistor checkers show lower hfe than it actually is... I would try using a variable resistor, and increase voltage until collector current gets to 1 mA (1 volt across the 1k resistor on the collector) then measure voltage at the base and calculate the currents, base current being the difference between the (voltage drop -.6 volts) across one 10K resistor -0.6 mA (current across the 10K resistor to ground. Maybe use 5mA as that is the spec rating. The 0.6 volts is somewhat arbitrary - try calculating with .5 or .7 volts to get a range. YMMV
EDIT: pretty much what @gslikker suggested...
audiobeginne
Member
What value of VR should I try?Rhanks
What do you have on hand?
anything between about 5K and 50K. You want to increase the voltage until the drop across the collector is 5 mA (or whatever operating point you desire, then masure the voltage on the base terminal, and calculate the base current to determine hfe.
audiobeginne
Member
I think the new 30 pcs are not broken. The old part also measures hfe of zero.