Can this transistor tester show me hfe and leakage?

[Squirrel Murphy]

I know I can do it this way... but for $14 I thought a tester would be handy to have (my MM doesn't have a transistor socket). So I bought this. It's also kinda nice for measuring capacitors and resistors (I suck at reading the color bands).

I tested a BC108A and it shows that it's NPN, identifies the B, C, and E legs for me, and shows me B=171 and Uf=670mV. Not sure what the last 2 bits of info tell me. I expect a min hfe of 120 for this transistor. I think spec is 110 to 220 at 2 mA. I read the specs for the tester and assumed (yes I know) that "measure the current amplification factor" meant that it would show me hfe. And of course, for NPN, there's no leakage to show me anyway.

For PNP it also shows me ICE0 and ICEs (in mA). Maybe C->E current leakage?

What can I deduce from what it's telling me?

[Phoenix]

That tester is only good for rough sorting of silicon transistors, probably not very useful for germanium, although it will probably identify them as such.

B is beta, also called DC gain, or hfE. Uf is U=voltage, f=forward, so the forward voltage of the base-emitter junction.
ICE does indeed stand for I=current, C=collector, E=emitter, so collector-emitter leakage current. 0 would indicate zero leakage current.

Keep in mind that the values that it gives you will only be valid at the test voltages/current that the meter applies. Different test parameters will provide different results.

Still a useful product for rough bin sorting of transistors, lead identification, quick diode and LED testing, and it will also measure resistors, capacitors, and even zener diodes up to 4.5V.

[Squirrel Murphy]

B is beta, also called DC gain, or hfE. Uf is U=voltage, f=forward, so the forward voltage of the base-emitter junction.
ICE does indeed stand for I=current, C=collector, E=emitter, so collector-emitter leakage current. 0 would indicate zero leakage current.

Ah... OK. So I just threw an OC-44 in there and I got this:

8.0V at boot time (I thought it was just testing the 9V battery, but maybe this is also the voltage the meter is applying to the test?)
PNP
B=69-70
uf=142mV (not sure this matters to me)
Ice0 = 0.1mA (doesn't show me ICEs like it did with the NPN one)

So I have a device with gain of 70 and acceptable leakage of 100uA, right?

Why is the tester only good for rough sorting? Poor accuracy? How far off do you think it is?

[Phoenix]

Why is the tester only good for rough sorting? Poor accuracy? How far off do you think it is?

It's unlikely that the test parameters are particularly close to actual circuit values, and different parameters will dramatically alter results. If your circuit requires close transistor tolerances, then your test circuit should at least roughly reflect the final circuit parameters if you want accurate results.

EDIT:
Oh, and the test is probably quite accurate, with the caveat that it's only accurate for those test parameters. When this matters is say when you're trying to match transistors (particularly germanium), you may find two that are closely matched with the meters test parameters, but unfortunately the values of the transistors are rarely linear, so under different test parameters, they will likely not be so closely matched. Silicon transistors are of course much more consistent than germanium, so you should get decently useful results.
But who knows? Maybe this'll work perfectly for you, but there is a reason there are so many instructions out there for germanium test-jigs for Fuzz-Face clones.

[PRR]

> of course, for NPN, there's no leakage

It is NOT about NPN versus PNP.

Germanium leaks. Silicon doesn't (not so we care).

Yes, "most" GE were PNP, but a lot of GE NPN were made.

Early Si tended to be NPN, and a cent/buck cheaper, but both types were available from before Silicon was any good, and today the two types are the same price. NPN happens also to match our polarity-habit, so NPN still dominates.

> threw an OC-44 in
> B=69-70
> uf=142mV (not sure this matters to me)
> Ice0 = 0.1mA

Thanks you very much. I needed a reality-check for some Ge simulation. 0.142V is right in the ballpark.

> spec is 110 to 220 at 2 mA

Yes, we would like to know WHAT the test condition is; 0.5mA, 10mA, what?? New Si may be fairly flat over several decades, but some old Ge was smooched-up between low-current falloff and high-current falloff, so the actual test (and operating!) conditions matter.

[Squirrel Murphy]

It is NOT about NPN versus PNP.
Germanium leaks. Silicon doesn't (not so we care).

Yes, of course. I got in the habit of thinking about Si as NPN and Ge as PNP for some reason and it came out that way.

we would like to know WHAT the test condition is; 0.5mA, 10mA, what??

I don't know, but the tester feature list has a couple of hints:

"current is about 2mA"... may be referring to the LCD consumption.... "Working current: 9V voltage, stable operating current of about 20mA".

There's a manual but the website is entirely in Chinese.

I suppose I could read the supplied amperage off the component legs with a multi-meter...

[Kipper4]

I put the text in google translate for you and got a convoluted 404 message.

Maybe you could revisit it and do the same.

My visit has expired............Back Home.

[Squirrel Murphy]

Maybe you could revisit it and do the same.

Did some hunting and translating and searching... it looks like it's a partly a document storage site (versus a manufacturer site). Couldn't find the target doc. Wish I had a model number. Posted a query to dx.com to ask around but I'm not hopeful I'll get anywhere.

Anyway... thanks for the assistance. I understand this tester much better now and find it quite useful for simple measurements.

[electrip]

Probably all relevant information in this thread:
http://www.diystompboxes.com/smfforum/index.php?topic=108076.0

electrip