AC121 Transistor

Ge_aficionado · Status: Offline

AC121 Transistor

Matlock · Status: Offline

Buy a whole bunch of them and test them. They should be very good, cause they are Siemens. BTW, AC 128 isn't a good transistor type. So go and buy...

Matlock · Status: Offline

Looked at your datasheet, that's where I caught the Siemens, but if they are not Siemens, don't worry. Just buy and experiment.

rlbjr65 · Status: Offline

I ran across some of these once, as I understand it they have additional markings.

AC121-IV hfe 30 - 60 not much chance of getting a good one.

AC121-V hfe 50 - 100 good for Q1 in an FF recommended hfe is around 70 - 90 Also you might get a good one for a Range Master I think most recommend hfe around 90.

AC121-VI hfe 75 - 150 good for Q2 in an FF recommended hfe 90 to 120

AC121 -VII hfe 125 - 250 not much chance there either.

All that said Germaniums are also known to be leaky and very leaky ones are not good! So you will probably have to buy some and test them anyway. Check out R.G. Keens FF Tech. page, there is a simple test jig for checking leakage so you can get an accurate hfe reading. http://www.geofex.com/Article_Folders/fuzzface/fffram.htm

Go to http://www.datasheetarchive.com type in AC128 the first listing for the AC128 has a PDF file that contains a great chart listing the specs for 60 or so germanium transistors. I don't know why but sometimes clicking on the pdf bumps you to another page, don't worry, just scroll down to get the PDF.

Hope this helps. Richard

Matlock · Status: Offline

Yup... I printed the chart from datasheetarchive.com last summer and it's been a
great help to check which are good and what kind of types there are.

I just love the AC 122 for fuzzes.