NPN Germanium sources?

[drgonzo1969]

I was troubleshooting earlier today and realized I am woefully under stocked NPN germanium’s. I’ve got tons of PNP for some reason. I have a few projects coming up that call for NPNs so gonna hit ebay. Anybody got any decent sources they like for NPN germanium’s? Ukrainian? Japanese? Russian? What’s good? I don’t shit really.

 

[jwin615]

I don’t shit really.

Try more fiber.
MP38As are solid with higher hfe but they've gotten expensive(for ruskies). 50 cents/piece is a good deal
$1/ea seems typical.
Non-A variant is lower gain.

These are decent lower hfe low leakage(tennis and 20s uA mostly) if your buying 40+(to counteract shipping)

(20 ea) 2SD128 Sony NPN Germanium transistor Japan NOS RF HAM radio receiver | eBay

2SD128 NPN Signal Germanium Transistor Sony Made in JAPAN. One lot = 20 ea., NOS, kept in plastic bag for many years ago. a bit dirty & logo warn. cost start 16 USD plus 2 USD for extra item.

www.ebay.com

Most of the 2SD germs are serviceable but check the datasheet

If you're looking for something in particular, PM me. It might take a couple weeks though. Headed to Baltimore for a while early in the morning.

 

[darwin999]

Sellers alexer1 and SOVCOM on eBay are very legit Ukrainian suppliers of Soviet Ge transistors- actually I believe they are from the same guy, Oleg. If you order multiple items, make sure to request combined shipping - he responds promptly with a reduced shipping cost.t

 

[zeropluszero]

I've just got some bits from elebcz on eBay, took around 5 weeks to Australia for post but they're here finally.

 

[owlexifry]

I've just got some bits from elebcz on eBay, took around 5 weeks to Australia for post but they're here finally.

how did they measure up?

 

[zeropluszero]

I only have a TC1 here, but as best i can tell they're within the specs I asked for.

 

[PedalBuilder]

NPN germanium is much more of a pain to source. For one, it's really hard to find anything with an hFE between 70-150. Most of the European devices that I've received (AC175, AC187, GC521) are ridiculously leaky—over 1500µA at room temperature. NPN germanium tends to be anywhere from 2-4x more expensive than PNP germaniums with the same gain. If you can ever redesign a circuit to use PNP germanium instead of NPN, I highly recommend doing so. If you can't redesign the circuit to accommodate PNP germanium, here are some options. All gain and leakage measurements were done with a Peak DCA55 at 70ºF.

MP35 - Typical hFE 45-55, leakage 50-100µA
MP38 - Typical hFE 50-60, leakage 50-100µA
MP38A - Typical hFE 60-70, leakage 100-150µA
2N1308 - Typical hFE 150-200, leakage 50-100µA
3BX31A - Typical hFE 50-60, leakage 100-200µA
3BX31B - Typical hFE 50-70, leakage 150-300µA

(If you're building a Hoof, any of the Soviet devices that I listed are great choices. You can use 2N1308, too, if you want a nastier, more silicon-like fuzz. EQD has used both lower gain Soviet transistors and higher gain western transistors over the years, too, for what it's worth.)

 

[juice886]

Another soviet NPN germaniums are GT404. However they are even larger than usual MP38-like stuff.
GT404A are usually low gain (~50 or so), while GT404B/D have rather high gain, sometimes more than 150, and GT404I/E are somewhere in between those. Not very consistent but that is a common issue.

 

[Cybercow]

I just got some of the Sanyo NPN Ge BJTs from SmallBear that measure very nicely between Hfe = ~62 to ~92 with leakages around & below 100µA. SmallBear's 2N1306 NPN Ge BJTs are pricier, but also very nice.

 

[CheapSuitG]

S

NPN germanium is much more of a pain to source. For one, it's really hard to find anything with an hFE between 70-150. Most of the European devices that I've received (AC175, AC187, GC521) are ridiculously leaky—over 1500µA at room temperature. NPN germanium tends to be anywhere from 2-4x more expensive than PNP germaniums with the same gain. If you can ever redesign a circuit to use PNP germanium instead of NPN, I highly recommend doing so. If you can't redesign the circuit to accommodate PNP germanium, here are some options. All gain and leakage measurements were done with a Peak DCA55 at 70ºF.

MP35 - Typical hFE 45-55, leakage 50-100µA
MP38 - Typical hFE 50-60, leakage 50-100µA
MP38A - Typical hFE 60-70, leakage 100-150µA
2N1308 - Typical hFE 150-200, leakage 50-100µA
3BX31A - Typical hFE 50-60, leakage 100-200µA
3BX31B - Typical hFE 50-70, leakage 150-300µA

(If you're building a Hoof, any of the Soviet devices that I listed are great choices. You can use 2N1308, too, if you want a nastier, more silicon-like fuzz. EQD has used both lower gain Soviet transistors and higher gain western transistors over the years, too, for what it's worth.)

This is super helpful, thanks!

 

[lowpitch]

Most of the European devices that I've received (AC175, AC187, GC521) are ridiculously leaky—over 1500µA at room temperature.

That's a bummer. I had an alert for some AC187K back in stock at a big German electronics store (Reichelt), so I placed an order yesterday. Not even sure where these come from. Reichelt doesn't usually deal in NOS as far as I know. Should be here tomorrow or the day after. I'll post my findings then.

 

[PedalBuilder]

That's a bummer. I had an alert for some AC187K back in stock at a big German electronics store (Reichelt), so I placed an order yesterday. Not even sure where these come from. Reichelt doesn't usually deal in NOS as far as I know. Should be here tomorrow or the day after. I'll post my findings then.

It's possible that the ones that I received were rejects from someone's stash; I got mine from minifux1 on eBay, not an electronics retailer. I'd be interested to see how yours measure up.

 

[szukalski]

That's a bummer. I had an alert for some AC187K back in stock at a big German electronics store (Reichelt), so I placed an order yesterday. Not even sure where these come from. Reichelt doesn't usually deal in NOS as far as I know. Should be here tomorrow or the day after. I'll post my findings then.

They are. Leaky. As. Feck.

 

[lowpitch]

It's possible that the ones that I received were rejects from someone's stash; I got mine from minifux1 on eBay, not an electronics retailer. I'd be interested to see how yours measure up.

Not great So yeah, avoid the AC187K at Reichelt.

They are. Leaky. As. Feck.

So they are. Guess I got some cool new GE clipping diodes now.

 

[PedalBuilder]

That's actually not terrible. The hFE 63/383µA is a good candidate for Q1 in a Tone Bender Mk. II (with a 10k base-ground resistor). The hFE 107/484µA and hFE 104/512µA is within spec for Q3 in a Tone Bender Mk. III-style circuit. The others are probably useless for anything other than as clipping diodes, though.

 

[lowpitch]

That's actually not terrible. The hFE 63/383µA is a good candidate for Q1 in a Tone Bender Mk. II (with a 10k base-ground resistor). The hFE 107/484µA and hFE 104/512µA is within spec for Q3 in a Tone Bender Mk. III-style circuit. The others are probably useless for anything other than as clipping diodes, though.

I'll have to look into that. I wanted to use these in NPN Rangemasters if leakage wasn't too high but that's not going to work I guess.