Swap Shop!! Transistor Lonely Hearts Club

[jonclancy]

Just as it says on the tin. This thread is here for you to list your orphan transistors hoping that someone else will have a complementary part.

I'll be listing my Toshes soon - and am hopeful that between us we can marry up a few pairs!!

Cheers

Jon

[gommer]

I guess this will be hard to do. Every one has a slightly diferent matching method and the results of one method do not necessarily match with the results of another method.

Good initiative though, but maybe it needs a measuring/matching agreement first.

Cheers, Marc

[Deleted]

Mar 2, 2011 19:29:15 GMT gommer said:

I guess this will be hard to do. Every one has a slightly diferent matching method and the results of one method do not necessarily match with the results of another method.

Good initiative though, but maybe it needs a measuring/matching agreement first.

Cheers, Marc

[XTRProf]

Great! Can swap other components as well? I think we should list all those things that we have too much, due mostly to bulk buy, or don't need any more here as well if we wanted to rid of them.

[jonclancy]

Hi Chong,

That's a good idea - in separate threads for non-transistors.

Marc and Alex,

A good point as discussed on the other thread. I know a few of us use the Peak DCA 55 meter to measure Hfe and here are the specs:

Vbe accuraccy +-20mA
Hfe accuracy +-5Hfe

www.peakelec.co.uk/acatalog/jz_dca55.html

Between any pair of test clips.
Collector current of 2.50mA.
Resistance across reverse biased base-emitter > 60k.
Resistance across reverse biased base-emitter < 60k.
Drain-source current of 2.50mA.
Collector-Emitter voltage of 5V.
Thyristor quadrant 1, Triac quadrants I and III.
Subject to acceptable LCD visibility.
BJT with no shunt resistors.

I have these:

2SA1930:

139
142x2
143
144
145
146
147x4
148
149
155
156x2

All Vbes either 690mV or 700mV

Be looking to keep the quad for my 4 channels of Class A. Leo will be getting the pair of his choice. The rest are up for swaps.

2SC5171 I have are:

149 730mV
158 710 mV
179x2
189
195x2
197x2
200
203

All parts apart from ones listed measured at 700mV Vbe.


The 195 and 197 pairs are my best (almost) quad, and earmarked, but I am a little concerned by the 50Hfe difference between the 1930s and 5171s.

Calling Will and Shaun - what have you got, chaps?

Cheers

Jon

[Deleted]

I have just ordered the Peak DCA 55 to have a sort through my small stock. Just wondering, if I use it on some 'reclaimed' devices would it indicate they are in good order? I'm thinking of a few early attempted projects that didn't work so I replaced parts whether or not I suspected they were faulty and might still be fine.

Syd

[Will]

Hi Syd,

The dca will indicate an unknown part if it's broken, so will certainly be useful in that respect. There might be the odd part that is faulty, but indicates OK, if it's only faulty under proper load. One fault I had years ago was a good one. A fuse was reading OK when tested by a meter, but went open under load.

[Deleted]

Thanks Will. At least I guess nothing should get damaged if I use only those that appear OK. Might never use any of them (the used ones) of course.

Syd

[Deleted]

Guys
Just remember that these testers use a nuch higher base current than normal to permit the software to correctly identify the type of device being tested. If you check the data sheets for the ON BC549C
you will notice that with a typical BC549C that VBE is 620mV at 2mA collector current.
Allan found when using his tester with smaller devices like those, due to the high base current used , most of them had almost identical HFE ! When I tested them using the 10uA base current setting of my meter, there was quite a large variation in HFE !
I know which I would prefer to use for matching small signal devices .
Alex

Attachments:

[jonclancy]

Interesting thread this, Alex.

It struck me that it would be useful to know what the base current is in the Class A - maybe Hfe matching should be tailored for each application?

I will be comparing my DCA55 results with the Hfe measurement on my Rapid multimeter.

Cheers

Jon

[Deleted]

100mA / Hfe = base current.
It will be around 0.6mA, for Hfe around 160.
the base curent of the BC327/337 will be between 5uA and 20uA depending on Hfe.

[Will]

Allan found when using his tester with smaller devices like those, due to the high base current used , most of them had almost identical HFE ! When I tested them using the 10uA base current setting of my meter, there was quite a large variation in HFE !

I've not found this to be the case myself, with the devices used in the class A, or bc550c/560c, 639/640. The dca has shown a wide and disparate range of results within the range of the transistor.

I've had a batch of bc337-40 land, as they show a wide range as well, from a quick test.

[Deleted]

One for the Poms.
("Beautiful one day, and freezing for the rest ?) ;D

Want "hotter" 2SA1930 and 2SC5171 ?
Simple ! Fit a standard 25mm high heatsink (17C/W) instead of the
expensive one, or the larger heatsinks.
See attached chart for HFE vs. temperature. (click on to enlarge.)
Alex

Attachments:

[jonclancy]

You know, the whole of this discussion about Hfe measurement is detailed on pages 15 and 16 of the DCA55 manual...

So, to start afresh: list your orphan transistors measured with a DCA.

I've learned some stuff about this, so thanks for all your inputs Alex, Frans, Marc et al.

BUT... the DCA will still measure and match within its own parameters and thus is still a very valid tool for this job!!

So there!

[jonclancy]

[Deleted]

BUT... the DCA will still measure and match within its own parameters and thus is still a very valid tool for this job!!

Agreed. It is far superior to a typical DMM, and it can measure VBE too. I still wouldn't swap my DIY transistor tester for one though.
So there!
Alex

[jonclancy]

So, best you tell us how it works. Then we knock up a purpose-built board. RG then has the best matched kit out there.

Stick *that* in your pipe...

[jonclancy]

Chong has asked about resurrecting this thread. I have listed my DCA55 measured Toshes. Anyone else care to chip in?