How to measure the gain (hfe) of Germanium Transistors

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DIY Guitar Pedals

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DIY Guitar Pedals:
How to measure the gain (hfe) of Germanium Transistors

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@DiyguitarpedalsAu 12 жыл бұрын

Oh, the annotation says "fuzz circuits". In the video i said "fuzzface" but i meant "most fuzz circuits". Ill check out the website thanks!

@Gledii 11 жыл бұрын

Hey Paul, I've just saw the in the same link you mentioned the RG.Keen measuring the voltage directly in a similar way. I've tried with silicon transistors but I didn't get any value , prob I built it wrong... Using the method you described, can I use a reset computer switch for it right?

@SweetChinMuzik1 7 жыл бұрын

do you believe in the "mojo" claims between the vintage germanium brands? like ge vs tungsram? i ask because I want to build a deacy amp and some people swear the ac126 has to be a ge or siemens..but tungsram are the only ones I seem to locate

@plexibreath 2 жыл бұрын

Great video! Since Small Bear just closed for good, where would I find that schematic for the circuit for testing germanium transistors?

@erikvincent5846 2 жыл бұрын

I'll give you two videos that can help there: kzfaq.info/get/bejne/mOCHdcWHtc2of6M.html and kzfaq.info/get/bejne/r9uYh7h2zsCXeYE.html

@plexibreath 2 жыл бұрын

@@erikvincent5846 Thanks, I'll check them out.

@Ihavealltherightstuf 11 жыл бұрын

hey I noticed the values of the components in this circuit are a little different from the one on "geofex". They both function the same way right? As far as the conversions I mean.

@Ihavealltherightstuf 11 жыл бұрын

Yeah I understand that germaniums cant always be accurate. But to be more specific I could I use this formula on either transistor tester?

@masonadams1460 11 жыл бұрын

I have two micronta products: a go-no go dynamic transistor checker from the 70's, a 22-175a true RMS DMM from the 80's with masses of buttons on it's faceplate and a benchtop design, and both of them read accurate gains for Ge, in around the 20-30 range for mp25 transistors. This could be as they are very low leakage, or the meters might have the proper circuitry to load them properly. In contrast, the dynamic checker can't show accurate Si transistor gain, but the 22-175a can.

@KStarDid 3 жыл бұрын

I just have just measured the HFE of an AC126 ge sold as "hfe"100-110" and found 250 on 2 different multimeters ??? What do you think about this ?

@erikvincent5846 3 жыл бұрын

A couple of different things can be the "throw-off". The very act of touching the transistor will change it's hfe pretty drastically. When I measure them, I usually have them in a fixture of some sort and then I wait a good 1 - 5 minutes before measuring. I can watch the "hfe" double or triple, depending on hand contact. We did an updated video of this here: kzfaq.info/get/bejne/mOCHdcWHtc2of6M.html which also includes subtracting the leakage from the gain, which that might be the other problem, different people measure the subtraction in and some people don't. True gain, however, shouldn't include the "leakage gain", as that is not real gain.

@bluemoth5990 3 жыл бұрын

The problem I encountered is that the voltage readings take a long time to stabilize. Should I wait for them to stop moving or take note of the first value when I switch on the multimeter? Thanx

@erikvincent5846 3 жыл бұрын

We did an update on this one here: kzfaq.info/get/bejne/mOCHdcWHtc2of6M.html but if the multimeter is good, the "stabilization" may be temperature swing. If that's the case, all of those values are "correct", which is why Germanium Transistors are so unpredictable.

@pahaahv 10 жыл бұрын

Unfortunately, it didn't work for me. I even tried soldering the transistors to the circuit, multimeter only could read the voltage of the battery from the circuit. But the transistors I have are some old soviet ones. Maybe I have destroyed them somehow, because I read they can't bear static and other kind of such shit.. but like this.. god knows....

@DiyguitarpedalsAu 11 жыл бұрын

The alligator clips are connected to the points where the multimeter is connected to on the schematic. You'll probably have to read up a bit on basic electronics to learn how to put this circuit together, its not really something i can explain to you through YT comments. Sorry.

@lorenzowynberg 7 жыл бұрын

Great Video :) Can you post a link of this schematic?

@erikvincent5846 3 жыл бұрын

We did a new one of this topic that includes the schematic: kzfaq.info/get/bejne/mOCHdcWHtc2of6M.html

@DiyguitarpedalsAu 11 жыл бұрын

'probably', sorry not totally sure, you'll have to read through the geofex article, he explains the formula in there. Or use the small bear circuit, its really easy! good luck

@DiyguitarpedalsAu 11 жыл бұрын

This is the small bear germanium transistor tester, simpler, not as accurate i believe. I personally dont mind as germanium transistor readings are all over the place anyway (due to temperature).