AC176 suitable for NPN Germanium circuits?

Hides-His-Eyes · Post by **Hides-His-Eyes** » 01 Apr 2010, 10:40

Suitable or will the Hfe be too high?

http://cgi.ebay.co.uk/100-of-AC176-germ ... 4839fd50e7

100 for £14 sounds like a fantastic deal, especially if any of you guys would have use for some of them.

IvIark · Post by **IvIark** » 01 Apr 2010, 10:47

They'd be great, the gain range is from 50 to 250 by an old datasheet, but the last time he listed those starting at £7.99 they ended up finishing at £70

Hides-His-Eyes · Post by **Hides-His-Eyes** » 01 Apr 2010, 11:45

Really?

My goodness. I'll keep a quiet eye on them then.

Whoismarykelly · Post by **Whoismarykelly** » 02 Apr 2010, 03:44

Tungsgram transistors aren't the most consistent. I bought a lot of 150 Tungsgram AC125 from him and only about 1/3 were usable. Keep that in mind.

makidra · Post by **makidra** » 10 Apr 2010, 18:47

... the same story., - i bought by him a lot with 10 Ac 125 ... crap

mictester · Post by **mictester** » 10 Apr 2010, 19:59

Hides-His-Eyes wrote:Suitable or will the Hfe be too high?

http://cgi.ebay.co.uk/100-of-AC176-germ ... 4839fd50e7

100 for £14 sounds like a fantastic deal, especially if any of you guys would have use for some of them.

Watch the auction carefully! If you can get them at a sensible price, they're fine for most germanium effect projects. If they're sensibly priced, I'll buy a few from you if you get them!

swaptronics_tech · Post by **swaptronics_tech** » 27 Jul 2010, 19:08

I bought a batch of 100 AC176 off e-bay for $41 USD. The guy in Germany shipped them fairly quickly, but when tested, they all measure 300 to 400+ on gain.

When tried in my BC-108 fuzz circuit, they acted like they were "open" and wouldn't adjust the bias of the Q2 transistor to 4.5 Volts.

The whole bunch is a load of crap--leaky and worthless.

I was excited to try these out in an NPN circuit because (if proper gain had been received) they would have been suitable for a 9V adaptor jack like the BC-108's are.

Silicon transistors can be used in the gain range of 200 to 400 with very good results.

However, germanium past 225 hfe or so are too leaky in my experience.

These were supposed to be NOS Tungsram and appeared to have not been used. However, the packaging was just a plain zip lock bag, etc.

I've had the very best results with 2N404A NOS Texas Instruments transistors with gold-plated leads.

Also, SFT-322 from Bulgaria work very well in germanium fuzz face builds.

Best regards,

Dave Adams (a.k.a. "swaptronics")

mictester · Post by **mictester** » 27 Jul 2010, 19:19

What did you check the gain with? Some meters give silly readings when they encounter some leakage!

Do you want to do a deal for some of them?

They won't be completely useless - I've used them in Tonebender-type circuits with great results. I had to mess with the resistor values a bit to get the bias sane, but they all worked really well. The last time I built things with germanium, I had to build a test jig to get the bias right.

The other thing you can do with them is a "Rat"-type circuit, with the germanium transistor in place of the FET - beating the hell out of a germanium with the output of an op-amp gives some amazing sounds - circuit diagrams to follow!

Dirk_Hendrik · Post by **Dirk_Hendrik** » 27 Jul 2010, 20:25

mictester wrote:What did you check the gain with? Some meters give silly readings when they encounter some leakage!

Do you want to do a deal for some of them?

They won't be completely useless - I've used them in Tonebender-type circuits with great results. I had to mess with the resistor values a bit to get the bias sane, but they all worked really well. The last time I built things with germanium, I had to build a test jig to get the bias right.

The other thing you can do with them is a "Rat"-type circuit, with the germanium transistor in place of the FET - beating the hell out of a germanium with the output of an op-amp gives some amazing sounds - circuit diagrams to follow!

Mictester speaks some important thruth here. There's loads and loads of people focussing on Ge transistors and all they seem to be applied to are fuzzface like circuits. Try something else. That leaky trannie might be a a lousy amplifier but a perfect toneshaper, like the above RAT example.

I have a simple breadboard circuit here that basically consists of 2 cascaded amplifier stages based on, non-selected at all, AC127's from the junk box. I've kept on playing over the last 2 weeks... Swapping for other AC127's... little to no change in sound.

jrod · Post by **jrod** » 28 Jul 2010, 14:00

Please forgive my ignorance, but what do you mean by "tone shaping" as in the RAT example?

You guys have made a great point! Most of the focus does revolve around Fuzz Face type circuits. I know RnFR has designed a couple of circuits that use low gain germs that would otherwise be unusable in a Fuzz Face. So, it would be cool to see some other uses for low gain or leaky transistors (other than for clipping diodes and buffers).

sidseizure · Post by **sidseizure** » 28 Jul 2010, 20:44

If you have your heart set on making a Fuzzface, but only have leaky germanium transistors, put a silicon transistor in Q1 like in Joe Gagan's Easy Face. You'll be surprised at what kind of leaky, low gain garbage germanium transistors you can use in this combination. This Si/Ge sounds great and is easy to bias with the typical 10k trimmer in place of the 8.2k resistor.

exactopposite · Post by **exactopposite** » 20 Oct 2010, 01:19

So how low (gain) is too low for a fuzzface? When they are too low does it now work or does it not sound good? Ive seen mention here and elsewhere about this, but I have never seen this answered. (i'm sure it's been answered, but I haven't found it)

Seiche · Post by **Seiche** » 23 Feb 2011, 11:33

hey ppl,

i have just found this as I am browsing for NPN Ge Transistors at the moment. The AC176 seems like an idea. The 2N404 thats also mentioned here is a PNP device. Has anyone any other help, which NPN germaniums are best value to money ratio? I want to use them on a couple of fuzz faces.

cheers

DrNomis · Post by **DrNomis** » 23 Feb 2011, 11:43

Seiche wrote:hey ppl,

i have just found this as I am browsing for NPN Ge Transistors at the moment. The AC176 seems like an idea. The 2N404 thats also mentioned here is a PNP device. Has anyone any other help, which NPN germaniums are best value to money ratio? I want to use them on a couple of fuzz faces.

cheers

Have you checked out Caps N' Such?, there are some NPN Ge transistors with good gains, plus they are all pre-sorted so you shouldn't end up with any duds....

I bought a set of 5 PNP Ge Transistors and they were all good...

Seiche · Post by **Seiche** » 24 Feb 2011, 09:45

thanks for your help, but caps n such only has "germanium transistors" (no model number like ac128) and they are >3 dollars each pretested, or 5 in a bulk untested for 13 bucks. I could probably go cheaper with testing myself. Also they are PNP. I'm looking for NPN to make it easier to use one power supply with all of my pedals.

I was looking at the MP38A:
http://cgi.ebay.de/ws/eBayISAPI.dll?Vie ... K:MEWAX:IT
by this seller http://stores.ebay.de/Next-Lux
Anyone have any experience with those? I think they have relatively low gain, but don't know whether this is good or bad. I never turned up my fuzz face all the way, but i know some ppl do.

I was also looking at the AC176 from Ebayseller "minifux1" but i think someone already mentioned they got a 100 pack from a german supplier(I assume they mean minifux1) and they were all crap, so I'm still hesitant.

IvIark · Post by **IvIark** » 24 Feb 2011, 09:51

For NPN I bought 50 x MP38A from gordelux04, gain ranged from 54 to 90 and leakage was low in all of them, between 0.11 and 0.23mA. In the past I've bought a big batch of GT404B Russian NPN germanium and although gain was higher (60 - 170), leakage was poor in most of them.

DrNomis · Post by **DrNomis** » 24 Feb 2011, 10:11

Seiche wrote:thanks for your help, but caps n such only has "germanium transistors" (no model number like ac128) and they are >3 dollars each pretested, or 5 in a bulk untested for 13 bucks. I could probably go cheaper with testing myself. Also they are PNP. I'm looking for NPN to make it easier to use one power supply with all of my pedals.

I was looking at the MP38A:
http://cgi.ebay.de/ws/eBayISAPI.dll?Vie ... K:MEWAX:IT
by this seller http://stores.ebay.de/Next-Lux
Anyone have any experience with those? I think they have relatively low gain, but don't know whether this is good or bad. I never turned up my fuzz face all the way, but i know some ppl do.

I was also looking at the AC176 from Ebayseller "minifux1" but i think someone already mentioned they got a 100 pack from a german supplier(I assume they mean minifux1) and they were all crap, so I'm still hesitant.

Caps N' Such do stock NPN Ge transistors too...

Seiche · Post by **Seiche** » 24 Feb 2011, 11:05

really? i was just looking at the website(http://www.capsnsuch.com/index.php?rout ... path=41_42) and couldn't find any??!

maybe they're out?

For russian PNP I also found GT108B and P416A from gordelux04
They seem spot on and cheap. Anyone have experience with any of them?

The P416A are HF (high frequency?), does this lead to any problems when using them in a FF for example? He says they are "the best" and "This production of the highest quality intended for application in space researches". I don't really know why this sounds so intriguing

http://cgi.ebay.de/ws/eBayISAPI.dll?Vie ... K:MEWAX:IT

IvIark · Post by **IvIark** » 24 Feb 2011, 12:01

I've got some P416A and GT108G as well. The P416As sound great in a Fuzz Face circuit but they're relatively low gain, they ranged from 40 to 70hFE and have zero leakage. They look very similar to the GT308B, same case design but painted grey instead of bare metal, but the GT308B's are probably a better choice because they seem to be slightly higher gain, going from 56 to 90 and again with zero leakage.

The GT108G's are cool. They're really small (smaller than a metal can silicon transistor) and were mostly in the higher Fuzz Face gain range, from 100 to 160hFE although a few measured much higher and were probably out of the useful range for us.

I've bought quite a few Russian transistors over the last few years and the only ones I've really been disappointed with are the NPN GT404B's. All the PNP ones have been good purchases.

DrNomis · Post by **DrNomis** » 24 Feb 2011, 12:06

Seiche wrote:really? i was just looking at the website(http://www.capsnsuch.com/index.php?rout ... path=41_42) and couldn't find any??!

maybe they're out?

For russian PNP I also found GT108B and P416A from gordelux04
They seem spot on and cheap. Anyone have experience with any of them?

The P416A are HF (high frequency?), does this lead to any problems when using them in a FF for example? He says they are "the best" and "This production of the highest quality intended for application in space researches". I don't really know why this sounds so intriguing

http://cgi.ebay.de/ws/eBayISAPI.dll?Vie ... K:MEWAX:IT

I've used some PNP Ge transistors that I got from an old HP Frequency counter that used Nixie Tubes as display devices, the counter could work with very high frequencies, anyway,I tried those transistors out in a Fuzz Face circuit and they worked fine....

I reckon buy some and try them out....