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Need help identifying transistors

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ritaismyconscience

Sat Jun 23 2018, 05:38PM

Registered Member #62937 Joined: Wed Jun 06 2018, 08:20PM
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Posts: 32

I looked on Google but I couldn't find the datasheets.

Sulaiman

Sun Jun 24 2018, 11:26AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

I do not recognise the part numbers and it may be very difficult to find datasheets because
at that time* it was common for larger product manufacturers have semiconductors custom labelled,
mainly to prevent third parties from repairing or copying electronic designs.

* date code 7935 = week 35, 1979 (1974 was a very confusing year for TTL IC identification)

The actual transistors will rarely be custom design, just common transistors re-labeled.

ritaismyconscience

Sun Jun 24 2018, 05:51PM

Registered Member #62937 Joined: Wed Jun 06 2018, 08:20PM
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Posts: 32

I found the datasheet for the 380-2 ones:

Patrick

Sun Jun 24 2018, 06:35PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

does it matter ? I.E. are you fixing original equipment ? can you figure out the functional requirements from the circuit, then identify current transistors that will work ?

figuring out the transistor specs via part marking is the most difficult way for old stuff as previously stated.

ritaismyconscience

Sun Jun 24 2018, 08:46PM

Registered Member #62937 Joined: Wed Jun 06 2018, 08:20PM
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Posts: 32

I bought a box of parts from ebay and these came with the box.
I have no idea what they were used in. It is impossible for me to find out the specs any other way. The parts seem to be from RCA.
I think I found the 3801 one too:

radiotech

Wed Jun 27 2018, 09:55AM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
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Posts: 1546

Please be careful. The A23 marked transistor on the upper left of
your first photo appeared to have an insulator hanging on.

This looked like a thermo conductive may have
been applied.

Some of these old electronic parts used deadly materials.these
substances came with warnings about handling, ingesting,
or breathing dusts.

Your Ebay package of used parts might contain hazardous content.

Some of the more senior members of the forum will have been
avoiding these materials decades before the internet started.

Attached is a warning about a transistor insulator that might be
found in old electronics made 50 years ago and may still be sold on E-Bay.

Sulaiman

Wed Jun 27 2018, 10:22AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

I have never even seen a berylium oxide TO-3 insulator - they were very rare,
(although I have seen a few transistors that have BeO internally - usually r.f. power devices)
Mica was the only common insulator of those times.
(with a razor blade or sharp knife edge you can split mica into thinner sheets)
----------------------------
I doubt that the datasheet that you found is for your 380-2 transistor,
as we did not have such good transistors back then ;)
and NTE did not exist until 1989 !
----------
I'd expect equivalents to 2N3055, 2N3773, 2N2955 and HOT/flyback transistors from TVs etc.
The smaller TO-66 transistor may be 2N3054.
I did not do TV repairs so no numbers come to mind, so you will need to do a little research.
There could even be a 78xx type regulator in that lot.
--------------------
So, as mentioned above, it is best not to use these transistors for a new design,
or even an old design - as the transistors are very old.
If you are building something new then use newer design/better transistors.
If it is just for knowledge/experience/experimenting then go ahead, but do not expect too much performance from those transistors.

radiotech

Wed Jun 27 2018, 05:17PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

The warning about the BeO insulator is part of an instruction manual for equipment
I currently own and use. Here is an E-Bay listing for the ultrasonic cleaner
I have.

For $120 US you can buy it today.

For $19 US, digikey will sell you a new BeO TO-3 size insulator.

Sulaiman

Wed Jun 27 2018, 08:26PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Well that is interesting,
I have several TO3 insulators that I've always just called 'ceramic'
It seems I may have BeO ceramic ... D'oh !
So it seems that possibly berylium causes memory and hair loss
- or is that just age :)

ritaismyconscience

Thu Jun 28 2018, 05:04PM

Registered Member #62937 Joined: Wed Jun 06 2018, 08:20PM
Location:
Posts: 32

The insulators do not seem to be ceramic, as they are clear and bendy. However, the heat sink compound might contain BeO according to Wikipedia.

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