new ac128's readings...

[darron]

hey all. i just got in some new ac128's from a company in australia. they don't appear to be nos but seem to be newly manufactured. i opened up a packet to try out my new (and only) eight dollar multimetre. i plugged it in according to this diagram http://www.vintage-radio.com/images/figs/transistor/pinouts.gif and got a reading of 14. i opened another packet and got 11.

these trannies with the red dots, though germanium are supposed to be very consistant. so...

1) are these alright? i bought four packets and opened two.
2) should i get my hands on another multimitre that doesn't leave the transistor feeling so loose when it's being tested?
3) duds?
4) are these actually new?



i'm quite the noob...

i've built a fuzz face with the standard tonepad layout (using negative ground) with some nos ac128's that were in some guy's shot once and by luck it sounded awesome.

thanks for feedback in advanced guys
i love you guys.....

[petemoore]

  Real low like that...could be / I think you've got the collector where the base goes...
  often as I get them turned around the wrong way when DMM checking the gain + leakage [See Geo article on how to pick transistors for a FF to calculate Gain - leakage], I get a reading like 8, more than likely those tranny's are something like GE's do normally...50-150+hfe readings indicate correct pinout [and something that'll work in a circuit~], keep switching the leads around in the DMM[though I believe the base stays in the middle on AC128's not sure tho]..until you get a 'normal' reading.?

[darron]

hey. my metre is touch. i just tried it backwards to the way that i believe it should be, and to the way the pinout diagram i listed shows it should be and got 194 and 142. id believe that to be true gain as these babies look new and from what i've read about these uk ones with the red dots they are very consistant.

thanks petemoore. i didn't want to try putting it in backswards in fear of ruining them. the packet also has a diagram that appears to show that i shouldn't touch it too? lol. i de-static'd myself incase.

they cost me about $4 each, and about $10 postage AU from RS Components, Australia.

[R.G.]

Did you read up on choosing and testing germanium transistors at GEO (http://www.geofex.com) first?

[darron]

Did you read up on choosing and testing germanium transistors at GEO (http://www.geofex.com) first?

i've read technology of the fuzz face. it has a little schem to calculate the leakage, but i don't have resistors that big lying around. i'd also have to get/make some mounts up.  it's quite a trip to the local electronics shot (jaycar) from here. i'm assuming that there's going to be little leakage with these.

i WILL test them out though.

[RaceDriver205]

No kidding! I didn't know RS had Ge Trans'! I gotta check this out, I don't live far from one of their retail outlets.

[darron]

No kidding! I didn't know RS had Ge Trans'! I gotta check this out, I don't live far from one of their retail outlets.

mail me some in the future? postage is a killer!

RS Stock No. 293-909

[petemoore]

RS Stock No. 293-909
  Pretty sure back in the day I got GE marked, Si looking [looked more like a 3904 or something] transistors, IIRC I didn't get much bang out of them, 15 to a packet.
  Once you get a FF working...well, you'll know it, and then you'll know also if somethings wrong like a Q pinout, and if anything like my FF experiences, noticing how different transistors sound in Qs' 1and2 positions...after biasing etc. then etc.
   194 and 142
  These gain + leakage readings look like normal, I would probably go with the pinouts marked on the DMM when these readings are shown.