NJW0302G and NJW0281G pin out - diyAudio
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Old 2nd April 2013, 06:15 PM   #1
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Default NJW0302G and NJW0281G pin out

Recently bought these transistors to replace some failed ones in an amp. They're different but should be compatible. However, I did not think to check the pin out before ordering -- doh! So I tried to look up the pin out and cannot find it?! It is not in the datasheet. Anyone know where the pin out can be found? Thank you.
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Old 2nd April 2013, 06:42 PM   #2
Mooly is online now Mooly  United Kingdom
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I can't find them either but its easy to identify transistor leads.

How much info do you have ? Do have a circuit diagram ?

If your not sure how to do any of this then ask but the info is all easily available.

You first have to identify each device as NPN or PNP. That's the easy bit and identifies the base lead in the process.

Then you have to identify E and C which is easy with a little ingenuity. You can rig each each device up with a 9 volt battery and resistor (say 10K) and LED.

For an NPN connect the battery negative to one lead (E or C) and the LED and resistor from the other lead to the battery positive. If the LED lights you have the transistor polarity wrong. If the LED doesn't light then connecting a resistor (say 47K) from B to battery plus should turn it on and confirm the connections. The collector is the lead that goes to the LED and the emitter is the one to the negative battery terminal.

The PNP can be identified the same way except this time reverse the battery polarity and LED. In other words think "positive earth"

Identifying connections on the PCB is also possible although it helps to know if you should be fitting an NPN or PNP in any given location. For NPN the print with the highest voltage will normally be the collector and the lowest voltage of the three points, the emitter.

Its much easier to do than explain Good luck...
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Old 2nd April 2013, 07:06 PM   #3
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Unfortunately, I do not have any of my electronics stuff here. All of my stuff is in my dorm, I go back in a few weeks though. I left my semiconductor analyser there - d'oh! I can probably identify the two diode junctions in the device, but then I do not know which end is collector and which is emitter...

I have seen these used before in projects here so surely someone knows what the pin out is? And why would someone produce a datasheet without probably the most critical specification?
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Old 2nd April 2013, 09:20 PM   #4
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Numbers up, left to right, BCE. You'll find the middle pin is connected to the tab, that's how you are sure it is the C. Download datasheets from datasheetcatalog.com. Most of the On Semi datasheets have 1,2,3 on the package drawing with a code table, but a few don't. They don't worry so much about onesies these days, On wants to sell a thousand at a time in an auto-insert magazine. Dream on, all that stuff all moved to ***** years ago. Buy them while you stlll can. NTE is in the onesies market, three times the price for incomplete specs on similar parts.
Did you read the whole spec from the place you bought them? I found newark selling NJW21194 for 1/3 the price of a MJW21194, with a power spec of 200 mw, and sure enough, many blew up when I put 85v on them at <10 ma. the datasheet says 200 W. I wonder if NJW is a way to sell the rejects?
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Last edited by indianajo; 2nd April 2013 at 09:27 PM.
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Old 2nd April 2013, 09:49 PM   #5
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Old 3rd April 2013, 06:16 AM   #6
Mooly is online now Mooly  United Kingdom
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Quote:
Originally Posted by tom66 View Post
Unfortunately, I do not have any of my electronics stuff here. All of my stuff is in my dorm, I go back in a few weeks though. I left my semiconductor analyser there - d'oh! I can probably identify the two diode junctions in the device, but then I do not know which end is collector and which is emitter...

I have seen these used before in projects here so surely someone knows what the pin out is? And why would someone produce a datasheet without probably the most critical specification?
The battery and LED test will identify C and E. You are connecting the transistor as a common emitter amplifier and applying base current to verify the connection. Two minutes of a job to identify a totally unknown device as either NPN or PNP and identify all the connections correctly
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Old 4th April 2013, 07:15 PM   #7
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The pin out stated does match the amplifier's design, which is good . I guess I'll turn it on and hope nothing goes "bang"!
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Old 4th April 2013, 10:21 PM   #8
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Read about light bulbs in series with the 120 vAC feed to the power transformer. If you have a switcher power supply I don't suppose that is applicable. This helps keep output transistors from blowing the die out the top if there is an error. Keep all 120 vAC inside a grounded box; mine has a fuse and a switch. I have a hundred watt edison base bulb in there, with the resistance side going to the hot of a receptacle for the amp I test. Pictures I see on other threads of wires going to a lamp socket on a board in the open strike me as the way to shock yourself silly.
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Last edited by indianajo; 4th April 2013 at 10:29 PM.
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