I´ve been testing some AC 128's and the methods (R.G Keens tester, Steve Daniels tester) doesn't work at all. When I hit the base with the lead the voltage in Keen's tester doesn't change. Steve's tester doesn't show the "forward base bias". Although it shows the leakage.
So, has anyone better testing methods for AC trannies??
Got today 6 AC 125's, though I ordered 20. They were out of stock. Anyway, I measured them with R.G. Keens tester and I got wonderful gains: 0,0,0,0,0,3. Every time the meter showed 0,34 V and when I put the 2,2M resistor to the base, the current didn't change. Is the fault in the man who's testing them, or are the F***ING AC'S SO CRAP??? I'm tired about the AC's. Maybe I should be playing with silicon devices and IC's and try not to waste time with those piece of ****ements???
Yup, that seems to be a very good device. ...But quite expensive. Especially when you order it to non UK- location. I don't think I'll buy it 'cause I don't have lots of money. But hey, thanks man for information about that very useful device!
R.G. transistor tester is working! I'v built and I am curently testing with it! Check out the wireing. Be aware that sometimes you may need to test a lot of AC's to get the righ gains and low leakige. And in fact AC's are leaky devices. I once tested about hundred to get just few right, sometimes you may hit on wery good ones too. Do not get tired and disapointed! Look for another bunch of them. That will take time and efforts and some money but you will be rewarded with the sound silicons are far behind. Also if posible find and use un old needle tester, it is better for this test.
Hope they gonna work better than this magic ''anal'' ones!! I got out some japsey germs from an old device, They were 2SB33's and 2SB32's. They were very useful in my proto hybrid faces.
I've been testing Ge transistors using RG's method and it works fine. But note that the current will modify the temperature and therefore the gain, so you'll probably see that the voltage varies for a few minutes until it reaches the equilibrium. Touch the thing with your finger and the voltage will jump. I also use the DDM to do a quick leakage test at the store where I buy the transistors. I simply bend the base lead and insert only the emitter and the collector. I calibrated the DDM with RG's test so I know which readings are ok.
I've read that some people have the same problem I had with the AC1xx. The ones I bought are useless. Unknown maker. Too much leakage and many of them were broken. As rule avoid generic devices. I recomend the japanese ones, mainly toshiba and matsu****a, in that order. The toshibas have an average leakage of 50uA and the matsu****as 120uA. Here is a list of gains, at least for the ones I have:
toshiba 2sa49: 70 to 170 2sa52: 52 to 75 2sa53: 20 to 60 2sb56: ??? matsu****a: 2sa101: 30 to 50 2sa102: 30 to 60 2sb176: 100 to 200 2sb175: 50 to 70
i like the toshibas for a fuzz face because the have a clean sound when rolling back the guitar volume. the matsu****as are good for a tone bender or a big muff as they sound more fuzzy.
Don't forget the American-made 2N-series Germanium transistors! I've used the 2N388/2N388A NPN Germanium and the 2N404 PNP Germanium. Those were very consistent and low leakage.
NPN Germaniums seem to be more solid when it comes to gains and leakage since NPN Germaniums weren't produced until the very end of the Germanium transistor era. By the time technology (as it was) improved enough so that they could easily mass produce NPN Germanium transistors, the Silicon models had started showing up. Of course Silicon quickly took over the market because of their stability and greater consistency.
DIYers will kill me if they know that these jap transistors are just five blocks away from my house... ... I heard a 2n388 tone bender clone. It sounds nice. Mine has 2sa102 - 2sa49 - 2sa49. Great too. But they sound different. I can't say which is best. If I could get some 2n388 i'll build one.
Anyway, I measured them with R.G. Keens tester and I got wonderful gains: 0,0,0,0,0,3. Every time the meter showed 0,34 V and when I put the 2,2M resistor to the base, the current didn't change. Is the fault in the man who's testing them, or are the F***ING AC'S SO CRAP??? I'm tired about the AC's. Maybe I should be playing with silicon devices and IC's and try not to waste time with those piece of ****ements???
