Transistor HFE observations.

[Zero Cool]

Now that i have my M3 transistor analyzer kit built. i decided to run through some transistors and see what i get.

On hand i have several sets of MJ15024/25 transistors and i was curious to see what i would get.

Set #1 is whats left from the Classe DR-15 amp i am rebuilding. these should have been matched at the factory.

Set #2 is a set of 5 i recieved as samples from OnSemi, these are from the same lot, but not matched in any way.

Set #3 is the new set of 4 from Classe that is supposed to be factory matched.

The results

Set #1
NPN - Hfe- 26, 28, 31
PNP -Hfe- 54, 55, 60

Set #2
NPN - Hfe- 32, 33, 35, 35, 36,
PNP - Hfe- 71, 72, 75, 76, 81

Set #3
NPN - Hfe- 7, 8, 8, 12
PNP - Hfe- 89, 89, 90, 93

Very interesting numbers!

The NPN's of set 3 i checked twice to make sure the numbers were right! Those all seem very very low! and interestingly, the PNP seem high as compared to the others.

Set#2 The samples from onsemi are all very close. not bad at all. much better results then i would have thought.

So now i am very curious about those low numbers. Hfe is listed as hFE = 15 (Min) @ IC = 8 Adc and hFE = 5 (Min) @ IC = 16 Adc

so those are all below listed minimum. Granted i was not testing at that high of a current. I need to read my manual of this transistor tester a bit more to find out exactly how the Hfe is measured. but just in comparison to the other devices those numbers seems interesting.


Zc

[Wavebourn]

Are you sure collectors and emitters of NPN in the set #3 are not swapped?

[DCPreamp]

Hi ZC,

Seeing your post, I fired up my M3 and pulled out some similar MJ15022/23 devices that I had previously tested with an older DMM/hFE tester. Keep in mind the last test I ran was several years ago and was a different temperature, humidity, etc. I also tested some other device in my stash and compared them to the datasheets to see how my spare devices and the M3 analyzer measured up.

Here are my numbers:

MJ15022s:
Previous hFE test: 56, 60, 55, 47, 74
New M3 hFE Test: 58, 60, 54, 49, 72

MJ15023s:
Previous hFE test: 91, 114, 10, 96, 134
New M3 hFE Test: 82, 101, 19, 85, 118

2SA1302:
91, 87, 90 (spec'd at 35 to 160)

2SC3281:
53, 70, 55 (spec'd at 35 to 160)

TIP35C:
46, 10, 41 (spec'd at 15 to 75)

TIP36C:
241, 136, 246 (also spec'd at 15 to 75, but the datasheet curves show hFE up towards 175)

I'm pretty sure transistor manufacturers run sample lots and pick statistical numbers that represent mean values. So, depending on date codes, sample lots, production-run volumes, and other factors, it seems hFE values can run +/- 200% or more.

From what the M3 literature said, and from what a couple builders commented on, the M3 tests at very low current levels and then uses some math to extrapolate the current gain. It's not perfect, but for the features and the price, plus from the measured accuracy I checked, it's very close. Besides, when I match devices, I make sure to match hFE as well as Vbe to ensure close tolerances. And I think as long as the M3 is predictable, it's the relative closeness of the hFE matching along with the absolute value that matter.

Paul

[Zero Cool]

Originally posted by Wavebourn
Are you sure collectors and emitters of NPN in the set #3 are not swapped?

HI Wavebourn,

One of the coolest things about the M3 tester, is that the leads can be connected in any fashion, the unit automatically figures out which pin is connected to qhich lead and displays it on the screen!

But, just to make sure, i connected the leads the same way each time.

[lineup]

Originally posted by Zero Cool
Now that i have my M3 transistor analyzer kit built. i decided to run through some transistors and see what i get.

On hand i have several sets of MJ15024/25 transistors and i was curious to see what i would get.

.....................

So now i am very curious about those low numbers.
Hfe is listed as hFE = 15 (Min) @ IC = 8 Adc
and hFE = 5 (Min) @ IC = 16 Adc

so those are all below listed minimum. Granted i was not testing at that high of a current. I need to read my manual of this transistor tester a bit more to find out exactly how the Hfe is measured. but just in comparison to the other devices those numbers seems interesting.

M3 transistor anayzer
... i do not now how that one works
... but some transistor tester is good to have
... makes 'matching' of devices a bit easier



MySelf, and others, too
still want to do some IN CIRCUIT testing of Gain, Volt Base-Emitter

Simple test could be do using only
- 12 Volt DC supply ( or one 12V CAR battery )
- some Power resistors
- a clever setup to generate 1 Ampere in TRANSISTOR Under Test
- your multimeter
- piece of paper to note results

- I often write the HFE directly onto each TO3
... or attach a little label, piece of paper with test data, onto the tested device
... so next time I build, I can quickly pick Transistors
... knowing some data


lineup

[rephil]

Hi all,

M3 analyzer : first time I hear from this one. Sorry.

I have done some evaluation of the hFE transistors too :

at Ic around 200 mA :

- MJE15030
max hFE = 114
min hFE = 60

- MJE15031
max hFE = 234
min HFE = 221

A tube has 50 transistors inside. So this is the result of 100 evaluations. These are original ONSEMI transistors.

It follows in the next post.

rephil

[rephil]

Hi all,

I have done also the evaluation of 40 transistors each of the TIP35C and TIP36C at Ic around 100 mA :

- TIP35C :
max hFE = 219
min HFe = 96

- TIP36C :
max hFe = 143
min hFE = 108

These are original ST (SGS Thomson) transistors, more than one tube each.

I have no problem with these to get well matched pnp-npn devices.

It follows in the next post.

rephil

[rephil]

Hi all,

I have now a question : are we (diy buyers) able to get npn-pnp transistors that are reasonably good matched ?

I think that we overlook old trannies as newer are up to date. I have heard that very good amps were done before the new transistors were on the market.

The only way I have to get newer devices is in getting them with someone else that has access to very good transistors. A big buy could be proficuous to all of us : cheaper and surely good transistors that it is possible to match ...

Best regards and Merry Christmas to all of you !

rephil

[john_ellis]

Hi all

I do not know the M3 tester, but I've been measuring the gains of transistors for amps for many years with a trusty multimeter and a set of resistors. Matching within 25% is usually possible from a few devices, but I try to match to 10% if I can.

You need to check the gain of the transistors at a range of currents. In particular old trannys have current gains which look like a roller coaster ride. For something like a 50W amp using 2N3055/MJ2955's, the min gain of 20 at 4A is OK for 8 ohm load. But the gain could be 100 at ~200 mA. I try to match over as wide a range from the operating current range if possible (eg 50 mA-4A).

Newer trannys with "flat" gain characteristics are much more ideal and should improve distortion levels at least a factor of 4x - and these usually have better NPN-PNP matching too

Cheers
John

[MikeB]

Originally posted by rephil
Hi all,

M3 analyzer : first time I hear from this one. Sorry.

I have done some evaluation of the hFE transistors too :

at Ic around 200 mA :

- MJE15030
max hFE = 114
min hFE = 60

- MJE15031
max hFE = 234
min HFE = 221

A tube has 50 transistors inside. So this is the result of 100 evaluations. These are original ONSEMI transistors.

It follows in the next post.

rephil

Yes, i am familiar with that problem, thanks to optimized processing techniques the mje15031 has only 5% variations within one batch.
I also have older mje15030/31, not from onsemi sample program, simply bought at some shop. With these the hfe's are all around, no problem to match. It seems that the mje15030/31 can no longer be recommended because of that issue. (mje15034/35 seem to be matchable)
It's sad to hear that you have 50 pieces of these, with no possibility to match.

Mike