Test Equipment Anonymous (TEA) group therapy thread

[bd139]

They probably tested as Ge and they tagged them up for ebay.



Boredom prevails today

[Specmaster]

Odd. I'd claim them just in case.

Yeh, already contacted the seller in Bulgaria they were listed GT1322 =SFT322 Germanium Transistors NEW NOS AC128 2N2706 EFT322, 20pcs but all have marked as TT1322 but I can't locate any data-sheets on them.

Ummmm... okay... So what do they test at? AC128s will be a PNP GE transistor with .28-.32 forward voltage and approx 100-130 hfe. Anywhere near that IRL?

This little bastard is still pretty popular (again) for guitar fuzzboxes; there actually is enough demand to support new production.

mnem

I'm getting a wide swing on hfe between 6 to 177 but most are around 89 to 100 and a uF of 142uv

[tggzzz]

God it is glacial; treacle doesn't begin to describe it. But, after all, it was fully intepreted with the object table; JITting was in the process of being invented, elsewhere.

Not elsewhere, but in fact invented for Smalltalk by L. Peter Deutsch as documented in the paper "Efficient Implementation of the Smalltak-80 System" DOI:10.1145/800017.800542.

Oh, I am well aware of that But he wasn't working for Apple.

Lovely bit of Smalltalk trivia, as documented in one of the dragon books... When bringing up an interpreter/environment for the first time, some implementers noticed that everything was working except that panes scrolled in the wrong direction. They eventually traced it to incorrect implementation of subtraction of negative integers.

I've never been able to decide whether that meant:

• Smalltalk is wonderfully robust, and works even if there are significant errors
• Smalltalk is so complex it is unlikely that people can determine that it is working correctly (nowadays s/Smalltalk/C C++ compilers/ )
• both of the above

[mnementh]

Odd. I'd claim them just in case.

Yeh, already contacted the seller in Bulgaria they were listed GT1322 =SFT322 Germanium Transistors NEW NOS AC128 2N2706 EFT322, 20pcs but all have marked as TT1322 but I can't locate any data-sheets on them.

Ummmm... okay... So what do they test at? AC128s will be a PNP GE transistor with .28-.32 forward voltage and approx 100-130 hfe. Anywhere near that IRL?

This little bastard is still pretty popular (again) for guitar fuzzboxes; there actually is enough demand to support new production.

mnem

I'm getting a wide swing on hfe between 6 to 177 but most are around 89 to 100 and a uF of 142uv

Whuf.... that vF seems crazy low, even for a historically known-flaky device like the AC128. No wonder the Component tester couldn't figure out what it was; probably thought it was a Schottky diode across a FET. That'll really screw up the biasing as well, since it's operating in linear mode; doubtful you'll ever get idle current down where it should be unless you completely redesign the circuit. 

   Here's a short dissertation on the history of this device in modern rock/blues music; the author describes it thusly:

But this wonderful piece of crap has a major drawback : completely random technical data in a VERY wide range. This means that any given theoretical design has something like 30% odds to function right away.

Of course, as easily zorched as GE junctions are, it's entirely possible they're 30-40 year-old production and half of them have been murdered by static-discharge in the intervening forever since they were manufactured. 

Good luck my friend... 

They probably tested as Ge and they tagged them up for ebay.



Boredom prevails today

Well, it paid off... that got a much-needed belly laugh from me this morning. 

Also, *SNURRRRRCH!* (and file away for later re-use) 

Sounds to me like they just pulled the AC128 out of their arse, taking advantage of its known broad range of technical specs as a catchall part number to sell random unknown "probably GE transistor" devices without actually having to produce any verifiable data. 

mnem
*back to sorting-ily Hell*

[PA0PBZ]

Yeh, already contacted the seller in Bulgaria they were listed GT1322 =SFT322 Germanium Transistors NEW NOS AC128 2N2706 EFT322, 20pcs but all have marked as TT1322 but I can't locate any data-sheets on them.

Type Designator: SFT322
Material of Transistor: Ge
Polarity: PNP
Maximum Collector Power Dissipation (Pc): 0.2 W
Maximum Collector-Base Voltage |Vcb|: 24 V
Maximum Collector-Emitter Voltage |Vce|: 18 V
Maximum Emitter-Base Voltage |Veb|: 12 V
Maximum Collector Current |Ic max|: 0.25 A
Max. Operating Junction Temperature (Tj): 85 °C
Transition Frequency (ft): 0.7 MHz
Collector Capacitance (Cc): 50 pF
Forward Current Transfer Ratio (hFE), MIN: 50

So... AC128 is 36V/1A and this one is only 18V/.25A. Not a real replacement I'd say.

[worsthorse]

Odd. I'd claim them just in case.

Yeh, already contacted the seller in Bulgaria they were listed GT1322 =SFT322 Germanium Transistors NEW NOS AC128 2N2706 EFT322, 20pcs but all have marked as TT1322 but I can't locate any data-sheets on them.

Ummmm... okay... So what do they test at? AC128s will be a PNP GE transistor with .28-.32 forward voltage and approx 100-130 hfe. Anywhere near that IRL?

This little bastard is still pretty popular (again) for guitar fuzzboxes; there actually is enough demand to support new production.

mnem

I'm getting a wide swing on hfe between 6 to 177 but most are around 89 to 100 and a uF of 142uv

Okay... I've been following this thread in my usual halfwitted way... are you looking for Ge transistors for your project? If so, PM me with the part numbers you need. I have a collection of them acquired while I was hunting for MOSFETs, mostly ECG.

I remembered them when someone mentioned fuzz pedals. I have a stack of apparently much-desired Ge transistors in the original box and I've been trying to figure out whether I want to go to the trouble of listing them on that auction site.

[mnementh]

I've seen them going for US$8-30 each, depending on the series. There's a fair bit of mythology about them; plus a bit of fact as regards how they "break down" at the linear/saturation threshold. Remember, we're talking about making a "sound"; these people are trying to figure out stuff that is part forgotten lore from the dawn of electronics and electric instruments, part auditory science, part electronics engineering. Things as simple as differing input impedance and slew rate from one amp to the next can mean the difference between "Getting it just right" according to a particular musician, to "almost there but not quite" to "completely FUBAR" according to another. 

The horrible part about trying to reverse-engineer & re-create this stuff is that while some of them were Tesla-like savants, many of the people who created these devices were themselves amateurs, with an imperfect understanding of how the circuits they designed actually did what they did.   

mnem
*back into my hole*

[mnementh]

Yeh, already contacted the seller in Bulgaria they were listed GT1322 =SFT322 Germanium Transistors NEW NOS AC128 2N2706 EFT322, 20pcs but all have marked as TT1322 but I can't locate any data-sheets on them.

Type Designator: SFT322
Material of Transistor: Ge
Polarity: PNP
Maximum Collector Power Dissipation (Pc): 0.2 W
Maximum Collector-Base Voltage |Vcb|: 24 V
Maximum Collector-Emitter Voltage |Vce|: 18 V
Maximum Emitter-Base Voltage |Veb|: 12 V
Maximum Collector Current |Ic max|: 0.25 A
Max. Operating Junction Temperature (Tj): 85 °C
Transition Frequency (ft): 0.7 MHz
Collector Capacitance (Cc): 50 pF
Forward Current Transfer Ratio (hFE), MIN: 50

So... AC128 is 36V/1A and this one is only 18V/.25A. Not a real replacement I'd say.

Yeah, dumbasses trying to sell crap often don't realize that while you in many cases you can sub a more robust transistor for a particular part in some applications, you cannot necessarily substitute the other way around.  Now multiply that by millions of 1d10ts on fleaBay and decades of electronics manufacture... 

mnem
No, really... I'm going this time. 

[bd139]

Indeed. There are very few reputable sellers shifting semiconductors. Usually best to get them from house clearance lots and mixed components lots now and sort and test.

Just spent the last 2 hours designing an SLA battery charger to replace a transformer/diode/capacitor and single resistor in my alarm which packed in yesterday. What a cheap arse hack. Very annoyed.

[Specmaster]

Yeh, already contacted the seller in Bulgaria they were listed GT1322 =SFT322 Germanium Transistors NEW NOS AC128 2N2706 EFT322, 20pcs but all have marked as TT1322 but I can't locate any data-sheets on them.

Type Designator: SFT322
Material of Transistor: Ge
Polarity: PNP
Maximum Collector Power Dissipation (Pc): 0.2 W
Maximum Collector-Base Voltage |Vcb|: 24 V
Maximum Collector-Emitter Voltage |Vce|: 18 V
Maximum Emitter-Base Voltage |Veb|: 12 V
Maximum Collector Current |Ic max|: 0.25 A
Max. Operating Junction Temperature (Tj): 85 °C
Transition Frequency (ft): 0.7 MHz
Collector Capacitance (Cc): 50 pF
Forward Current Transfer Ratio (hFE), MIN: 50

So... AC128 is 36V/1A and this one is only 18V/.25A. Not a real replacement I'd say.

Yeah, dumbasses trying to sell crap often don't realize that while you in many cases you can sub a more robust transistor for a particular part in some applications, you cannot necessarily substitute the other way around.  Now multiply that by millions of 1d10ts on fleaBay and decades of electronics manufacture... 

mnem
No, really... I'm going this time. 

Back in the day I remember that it was possible to buy books of transistor and diode characteristics and also of course their equivalents but they don't seem to be available now.

[Specmaster]

Indeed. There are very few reputable sellers shifting semiconductors. Usually best to get them from house clearance lots and mixed components lots now and sort and test.

Just spent the last 2 hours designing an SLA battery charger to replace a transformer/diode/capacitor and single resistor in my alarm which packed in yesterday. What a cheap arse hack. Very annoyed.

They don't want you to be able to repair things these days, its a throw away mentality, what the right to repair, its far better for the planet 

[bd139]

Back in the day I remember that it was possible to buy books of transistor and diode characteristics and also of course their equivalents but they don't seem to be available now.

"Get your tits out!" (as in Towers International Transistor Selector)

We now have this: https://alltransistors.com/ which appears to be copied out of it.

They don't want you to be able to repair things these days, its a throw away mentality, what the right to repair, its far better for the planet 

It's dead easy to repair. The battery is just knackered. It's been in there 7 years now which is not bad TBH. I hooked it out and found it's a small 2.9Ah Powersonic AGM jobby which you can't get now and the hole is only big enough to get a hooky looking Chinese one in there. Have measured current consumption under power failure and it's only 20mA so a 2.3Ah Yuasa jobby is fine for a couple of days or so. The charger just offends my engineering mind.

[bitseeker]

And a big warning about max power.

An external attenuator will help provide protection, but a DC block is also useful. Minicircuits does inline SMA 18GHz blocks relatively (this is RF) cheaply.

Note that if you power a UUT on/off it could still have transients which could "go through" the DC block.

There are attenuators inside the SA, but they are designed for linearity and frequency response, and won't dissipate much power.

Measure the noise power with a calibrated thermocouple/resistor; power meters are readily available on fleabay/hamfests, but working heads cost much more Alternatively estimate it from the "excess noise" spec and the bandwidth, and then apply an appropriate pessimisation factor.

Thanks, tggzzz. More homework required. I'll check out Minicircuits, too.

[Specmaster]

Back in the day I remember that it was possible to buy books of transistor and diode characteristics and also of course their equivalents but they don't seem to be available now.

"Get your tits out!" (as in Towers International Transistor Selector)

We now have this: https://alltransistors.com/ which appears to be copied out of it.

They don't want you to be able to repair things these days, its a throw away mentality, what the right to repair, its far better for the planet 

It's dead easy to repair. The battery is just knackered. It's been in there 7 years now which is not bad TBH. I hooked it out and found it's a small 2.9Ah Powersonic AGM jobby which you can't get now and the hole is only big enough to get a hooky looking Chinese one in there. Have measured current consumption under power failure and it's only 20mA so a 2.3Ah Yuasa jobby is fine for a couple of days or so. The charger just offends my engineering mind.

Yeh, I have the Towers book in PDF format 1974 edition and the  https://alltransistors.com/ is not unfortunately very user friendly as much of the information contained with in is not in English or in the same flaming units such as hfe for example  and of course while Towers does list 2N2706 as an equivalent for AC128, alltransistor.com does not list anything as being equal to a AC128. Equally Towers gives BC169 and 2N4923 as being equals to BD139, alltransistors.com does not mention either of those but it does list about 163 other types, no consistency at all 

[bd139]

There's a 1983 edition which is a lot more helpful. Mine is at my mother's house though

[mnementh]

Back in the day I remember that it was possible to buy books of transistor and diode characteristics and also of course their equivalents but they don't seem to be available now.

"Get your tits out!" (as in Towers International Transistor Selector)

We now have this: https://alltransistors.com/ which appears to be copied out of it.

They don't want you to be able to repair things these days, its a throw away mentality, what the right to repair, its far better for the planet 

It's dead easy to repair. The battery is just knackered. It's been in there 7 years now which is not bad TBH. I hooked it out and found it's a small 2.9Ah Powersonic AGM jobby which you can't get now and the hole is only big enough to get a hooky looking Chinese one in there. Have measured current consumption under power failure and it's only 20mA so a 2.3Ah Yuasa jobby is fine for a couple of days or so. The charger just offends my engineering mind.

Why? Lead-acid is happiest with a simple linear PSU float charge. DON'T try filtering it or any of that crap; the pulsing DC keeps the plates from crusting up. That PowerSonic probably IS the same frame as the YUASA 2.3A; just the YUASA is correctly rated.



You don't say...  And YES, Virginia... there WAS a time when Radio Shack WAS NOT just useless as tits on a boar hog. 

mnem

[med6753]

AC-128 = ECG102A = SK3004 = RS276-2007

BD-139 = ECG373 = SK3054/196 = RS276-2017

This is from the Master Semiconductor Replacement Handbook publish by TAB in 1982.

[bitseeker]

Lovely bit of Smalltalk trivia, as documented in one of the dragon books... When bringing up an interpreter/environment for the first time, some implementers noticed that everything was working except that panes scrolled in the wrong direction. They eventually traced it to incorrect implementation of subtraction of negative integers.

I've never been able to decide whether that meant:

• Smalltalk is wonderfully robust, and works even if there are significant errors
• Smalltalk is so complex it is unlikely that people can determine that it is working correctly (nowadays s/Smalltalk/C C++ compilers/ )
• both of the above

Woah, I think that's the first instance of Perl substitution in this thread.

[tggzzz]

Lovely bit of Smalltalk trivia, as documented in one of the dragon books... When bringing up an interpreter/environment for the first time, some implementers noticed that everything was working except that panes scrolled in the wrong direction. They eventually traced it to incorrect implementation of subtraction of negative integers.

I've never been able to decide whether that meant:

• Smalltalk is wonderfully robust, and works even if there are significant errors
• Smalltalk is so complex it is unlikely that people can determine that it is working correctly (nowadays s/Smalltalk/C C++ compilers/ )
• both of the above

Woah, I think that's the first instance of Perl substitution in this thread.

More like vi(le) or ed substitution! (I used emacs from the early 80s on)

Never looked at purl perl; never had a reason to use it. Always struck me as a boring hack.

My career was deciding what not to learn. Hence I ignored  Delphi, C++, C#, Perl, many microprocessors, etc because they were me-too variants of other things. In that vein, Perl was merely a bash shell on steroids

[bitseeker]

Ah, I didn't look at which came first. Looks like ed wins.

[mnementh]

AC-128 = ECG102A = SK3004 = RS276-2007

BD-139 = ECG373 = SK3054/196 = RS276-2017

This is from the Master Semiconductor Replacement Handbook publish by TAB in 1982.

   Yes, but we've been talking about AC128 or AC128/01, (which has a big aluminum block pressed onto it for heat dissipation). THAT is equivalent to an ECG158, which has the specs we've been bandying about. ECG102A is similar in spec and same outline, but 1/2 the I_C, considerably less P_D and a little higher f_t.

The NTE cross-reference is based on the ECG; in fact, for many years, many of their parts came through as ECG parts with their stickers on them. 

They show NTE158 still available from several vendors: http://dilp.netcomponents.com/cgi-bin/nteinc.asp?partnumber1=NTE158 including Newark, which has them for *Ouch!* $9.27 each.

mnem
*Dead-Tree version FTW*

[Specmaster]

I can find some ECG158's in the USA and at this price they will flipping well stay there as well, $216.39 shipping to the UK 
https://www.ebay.co.uk/itm/PHILLIPS-ECG-158-ECG158-NEW-IN-BOX/392308434952?

[Specmaster]

Odd. I'd claim them just in case.

Yeh, already contacted the seller in Bulgaria they were listed GT1322 =SFT322 Germanium Transistors NEW NOS AC128 2N2706 EFT322, 20pcs but all have marked as TT1322 but I can't locate any data-sheets on them.

Ummmm... okay... So what do they test at? AC128s will be a PNP GE transistor with .28-.32 forward voltage and approx 100-130 hfe. Anywhere near that IRL?

This little bastard is still pretty popular (again) for guitar fuzzboxes; there actually is enough demand to support new production.

mnem

I'm getting a wide swing on hfe between 6 to 177 but most are around 89 to 100 and a uF of 142uv

Okay... I've been following this thread in my usual halfwitted way... are you looking for Ge transistors for your project? If so, PM me with the part numbers you need. I have a collection of them acquired while I was hunting for MOSFETs, mostly ECG.

I remembered them when someone mentioned fuzz pedals. I have a stack of apparently much-desired Ge transistors in the original box and I've been trying to figure out whether I want to go to the trouble of listing them on that auction site.

PM sent.

[med6753]

I can find some ECG158's in the USA and at this price they will flipping well stay there as well, $216.39 shipping to the UK 
https://www.ebay.co.uk/itm/PHILLIPS-ECG-158-ECG158-NEW-IN-BOX/392308434952?

If you want I'll buy and forward to you. Let me know. 

[worsthorse]

Indeed. There are very few reputable sellers shifting semiconductors. Usually best to get them from house clearance lots and mixed components lots now and sort and test.

Amen to that. Buying pulls from ebay is likely to be an exercise in extreme disappointment.