abfackeln wrote:seems like these gains might have been a little different last night, but can't remember for sure)[/quote
This difference may be because of the difference in the room temperature they are measured at!Are those figures the real gain - I mean measured gain minus measured leakage?
Cheers!
Yep.. Germaniums change constantly.. even from just touching them.
Take a measurement, then hold them between your fingers for 10 seconds and measure again.
culturejam wrote: We are equal opportunity exposure artists.
If I recall, they were reading higher last night, but likely due to the residual heat from removal/handling. Also tested/measured everything last night, and then re-tested again this morning before posting, for consistency.
As for the gains of the germaniums, in re-reading the manual, I don't think the Peak facotrs in leakage:
DC current gain is simply the ratio of the collector current to the base current for a particular operating condition. The Atlas DCA measures HFE at a collector current of 2.50mA and a collector-emitter voltage of between 2V and 3V.
I'll re-measure tonight and post the gains, leakage, and B-E voltage drop.
abfackeln wrote:As for the gains of the germaniums, in re-reading the manual, I don't think the Peak facotrs in leakage:
I've been wondering about this as well. I emailed their tech support, and they said they'd get back to me. But that was 6 months ago.
If it appears that it doesn't factor out the leakage, maybe we could work up a simple formula to use the given gain and given leakage to arrive at an adjusted or "true" gain?
I tried this a few months ago, but math is not my strong point.
abfackeln wrote:As for the gains of the germaniums, in re-reading the manual, I don't think the Peak factors in leakage:
DC current gain is simply the ratio of the collector current to the base current for a particular operating condition. The Atlas DCA measures HFE at a collector current of 2.50mA and a collector-emitter voltage of between 2V and 3V.
None of the GT404s that I've ever had have had leakage readings like that, in fact all the NPN Russian trannies I've used have been pretty high. Is there a pic of these trannies?
"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP
Yeah, the Openhaus doesn't use GT404s. There is absolutely no chance of that, and I don't think they would make a good substitute either. I have some Tesla 104NU71, and something like that would probably be a better substitute, though the ones I have are rather low gain.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran
One of the small bear fuzz face sets would probably work pretty well as alternatives. If they are NPN, steve just started selling a few choices for npn fuzz face sets. I pair of CV7112 I bought recently had measurements very close to those listed here.
SPeter wrote:Look at page 3!
I've posted two pics!
I know what GT404s look like, I've got a bag of 100 sat in front of me. I'm talking about the trannies from the Openhaus
"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP
Those remind me of Texas Instruments NPN Ge I've handled before. I don't remember the part number. They were ones that I've seen big lots of sold on ebay before. They came in a large factory carton with the transistors stored in individual cells. I remember Weber bought a carton years back... probably all gone now.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran
The 2N1306 seems a very likely candidate atm......
The TI 2N130X series appear to have similar physical characteristics (as do others), and the 1306 seems to have the right Hfe range (1304 range seemed a little low, and 1308 range a little high). It's my understanding that these were later-issue Ge's and have low noise/low leakage.
I've got a handful of 2N1306s ordered and shipped this morning, for a lot less than what I've been seeing them for (~$4.00 ea) - should be here later this week. I'll measure with the Peak and report back.
SPeter wrote:Look at page 3!
I've posted two pics!
I know what GT404s look like, I've got a bag of 100 sat in front of me. I'm talking about the trannies from the Openhaus
Two weeks ago I got apart with 15 pcs. of my precious AC 128 trannyes for exchange of the same number of GT404B!What can I say - not impressed at all! First, though their gain range was listed 60-150 14 of them were between 60-65 and only one with a gain of 89!I This is their real gain measured with the R.G.Keen testing method (thanks R.G!)! And they are realy cumbersome in size compared to other well known brands! I've also measured at least 5 or 6 other different brands of russian Ge transistors and almost always their gain has been at the bottom of their listed gain range with just few exceptions!
Below is a picture of AC128, GT404b and 2N1308 Ge transistors!