I'm gathering components for a Klon clone and noticed some regular electronics sites selling 1N34A diodes for around $0.10. They are most likely newly made from China and I guess sold mostly to amateur radio hobbyists. The reputable stomp box sites are selling 1N34A for 5 or 10 times more, and they are said to be from old stock.
Has anyone noticed a substantial difference between expensive old stock and cheap new 1N34A in a Klon?
The three times I've ordered a (cheap) 1N34 diode from a 'regular electronics' shop, online or locally I received a 1N60P.
It did not look like a germanium point contact diode nor was it heat sensitive.
When I complained they said it was an 'equivalent part' with the same characteristics.
When asked why they listed it as 1N34 they said 1N34 was sold out long time ago.
I don't know if it matters in a Klon.
Quote from: PietS on February 04, 2021, 07:54:54 AMsold mostly to amateur radio hobbyists.
They warn/complain as well: https://www.petervis.com/Radios/making-a-crystal-radio/crystal-radio-diode.html
@j_flanders. Thanks for the warning and given that I probably can't tell them apart on looks alone I guess I'll just leave them be and spend a little extra for the real ones.
By the way, a local cheap site I was looking at actually lists them together with the 1N60 with the option to choose. From your experience not much of choice most likely.
Check out AMZ to see that I had a similar experience: http://www.muzique.com/news/fake-ge-diodes/
Most real Ge diodes comes in the larger DO-7 package while the cheap non-Ge replacements are in the smaller DO-35 that looks like a typical 1N4148.
regards, Jack
the Centaur Reissues is said to have the 1N34, not the 1N34A, idk if there is a difference, but aficionados seem to be able to tell the difference, especially with the gain knob set really low, haha
you could probably get the exact same sound with any Ge diode, maybe even Schottkey diodes.
i have also read reports of people putting 1N4148 diodes in the Centaur and they claim they sound nearly the same.
cheers, Iain
Genuine 1N34a will have a glass body wont they and can be very brittle if handled roughly, they also have a thick solid black line on the cathode side.
QuoteThe three times I've ordered a (cheap) 1N34 diode from a 'regular electronics' shop, online or locally I received a 1N60P.
It did not look like a germanium point contact diode nor was it heat sensitive.
When I complained they said it was an 'equivalent part' with the same characteristics.
When asked why they listed it as 1N34 they said 1N34 was sold out long time ago.
I don't know if it matters in a Klon.
Quote from: PietS on Today at 07:54:54 AM
sold mostly to amateur radio hobbyists.
They warn/complain as well: https://www.petervis.com/Radios/making-a-crystal-radio/crystal-radio-diode.html
What's happened is some manufacturers are making up numbers which look like the germanium part numbers but they are really Schottky's. If you look at the datasheets the are spec'd as Schottky's. Redefining a part number which has been Germanium for 50+ years to be a Schottky makes me think there's an intent to deceive. Of course you will get obvious fakes.
The 10mA test is a good way to determine if you have a Germanium or Schottky,
https://www.diystompboxes.com/smfforum/index.php?topic=117550.0
https://www.diystompboxes.com/smfforum/index.php?topic=117550.msg1126227#msg1126227
This video measures leakage current, but many multimeters won't go down that low,
https://www.youtube.com/watch?v=Lyos1D7_2OI
If you check 10mA and leakage you will have a very good idea where you stand.
Interestingly, the video mentions the "fake" germaniums and also mentions the diodes which are in fact Schottky according to the datasheet like I mention before.
Here's an example of the datasheet,
http://kdiode.com/admin/diotech_file/1N60~1N60P.pdf
I wonder, (sorry for thread hijack,) does anyone have any experience concerning the Tayda 1N34/1N34A's? Any comments?
Quote from: 11-90-an on February 04, 2021, 08:02:39 PM
I wonder, (sorry for thread hijack,) does anyone have any experience concerning the Tayda 1N34/1N34A's? Any comments?
I bought some several years ago from Tayda.
They looked like 1N4148 and voltage drop was .7v
I saw this site posted awhile back (Not sure where I saw it posted though, maybe madbean)
https://stompboxparts.com/new-jersey-semiconductor/
I haven't ordered any so I can't speak of their quality/usefulness.
QuoteI bought some several years ago from Tayda.
They looked like 1N4148 and voltage drop was .7v
Actually the casing is a good way to tell as well.
I think there's been good and bad reports about Tayda's 1N34/1N34A's.
You probably need a recent customer to give the all clear.
Quote
I saw this site posted awhile back (Not sure where I saw it posted though, maybe madbean)
https://stompboxparts.com/new-jersey-semiconductor/
Even the datasheet looks risky, they don't say Germanium or Schottky and the package looks like a Schottky,
http://njsemi.com/datasheets/1N34A.pdf
Quote from: dfx_pedalpcbs on February 04, 2021, 06:04:34 PM
Genuine 1N34a will have a glass body wont they...
The '34 has been produced in almost every package.
https://www.radiomuseum.org/tubes/tube_1n34.html
https://www.radiomuseum.org/dsp_more_tubepix.cfm?tube_pk=8526&type=T
https://www.radiomuseum.org/tubes/tube_1n34a.html
https://www.radiomuseum.org/dsp_more_tubepix.cfm?tube_pk=34150&type=T
Marlin P Jones has been in business almost since the 1N34 was introduced and they may be selling the real thing:
https://www.mpja.com/Pack-of-10-1N34A-Germanium-Detector-Diode/productinfo/32603%20DI/
Jameco mostly sells just what they claim.
https://www.jameco.com/z/1N34A-Major-Brands-Diode-1N34A-General-Purpose-Germanium_2220533.html
AES knows their customers will whine and moan if they don't get the real goods.
https://www.tubesandmore.com/products/diode-1n34a-germanium-low-leakage
Yes, I remember "100 diodes for $1!" when they shoved this obsolete Ge junk out of warehouses. Who knew?
I've seen "1N34As" for sale and it wouldn't surprise me if these are Schottky. My guess is the "s" could be the seller's way to tell them from the Ge part. They have listed them under Germanium diodes, but note they don't explicitly claim them as anything more than substitutes.
https://www.bitsbox.co.uk/index.php?main_page=product_info&cPath=140_141_142&products_id=3521
And, if they had any, these are the Ge...
https://www.bitsbox.co.uk/index.php?main_page=product_info&cPath=140_141_142&products_id=924
If you want the real thing, buy the old stock from reputable sellers, if they cost a few or lots a few more bucks, get them unless you need like 100 of them, just skip the 5.00 coffee at DD for a day.
FWIW, I used D9E's for this application as they have the same forward voltage. Sounds great at low and high gain settings.
Quote from: stallik on February 05, 2021, 08:44:06 PM
FWIW, I used D9E's for this application as they have the same forward voltage. Sounds great at low and high gain settings.
how do they sound when the Centaur is set fully clean? that's when the magic unicorn horn based super diodes have the most impact on the sound according to a lot of forums, hahahaha
cheers,
Yes. I have used D9B's and D9E's and they both sound great.
MC
Quote from: PRR on February 05, 2021, 02:06:22 PM
The '34 has been produced in almost every package.
.....
https://www.radiomuseum.org/dsp_more_tubepix.cfm?tube_pk=8526&type=T
.......
https://www.radiomuseum.org/dsp_more_tubepix.cfm?tube_pk=34150&type=T
......
couldn't see these links, needs sign-in.
Quote from: iainpunk on February 06, 2021, 07:23:50 AM
Quote from: stallik on February 05, 2021, 08:44:06 PM
FWIW, I used D9E's for this application as they have the same forward voltage. Sounds great at low and high gain settings.
how do they sound when the Centaur is set fully clean? that's when the magic unicorn horn based super diodes have the most impact on the sound according to a lot of forums, hahahaha
cheers,
Tried it turned all the way down. Really disappointed now :(
Sounds great but no unicorns to be seen anywhere
https://www.radiomuseum.org/dsp_more_tubepix.cfm?tube_pk=8526&type=T
https://www.radiomuseum.org/dsp_more_tubepix.cfm?tube_pk=34150&type=T
Quote from: duck_arse on February 06, 2021, 09:28:51 AMcouldn't see these links, needs sign-in.
(https://i.postimg.cc/t7h7qw2G/1-N34-s-42.gif) (https://postimg.cc/t7h7qw2G)
Quotehttps://www.radiomuseum.org/dsp_more_tubepix.cfm?tube_pk=8526&type=T
https://www.radiomuseum.org/dsp_more_tubepix.cfm?tube_pk=34150&type=T
For the package you won't get Schottkys in the glass cases (the fakers haven't gone that far yet). So a glass case is a good indication you have real germaniums.
It you get diodes that look like 1N914's or small Schottky's BAT46's the chances are they are not germaniums. The only old school package which even looks remotely like these is the your middle-left pic but if you look at it closely it still doesn't really look like the modern packages.
> glass case is a good indication you have real germaniums.
1N914?
Quote> glass case is a good indication you have real germaniums.
1N914?
I mean the glass case styles in your pic The common germanium package.
In other words if it looks like a germanium it is probably a germanium!
QuoteSo a glass case is a good indication you have real germaniums.
i guess my 2N4148's are germanium now, haha,
cheers
Thanks everybody for all the tips and pointers.
I got a few that were sold as 1N34A for $0.40 a piece at a local electronics shop. Glass casing, black line with red in center. They didn't look newly made so had good hope.
Forward voltage with diode test setting on cheapo DMM reads 160-170mV, nothing in reverse. Basic resistance measurement with DMM reads around 2K in forward direction and around 35k in reverse.
Then I tested forward voltage drop using a 9V battery and a 1k and 10k resistor. At 0.9mA there was a 0.16-0.18V drop and at 9mA a 0.25-0.30V drop. The different individual diodes I tested were quite consistent.
Reverse biased with 9V, I got about 5-6uA leakage current.
I'm not sure what to think. They looks the deal and they seem bit leaky like Ge diodes should be but the voltage drop with 9mA seems more like a Schottky.
Edit: I heated them up with a lightbulb while measuring forward voltage, and forward voltage actually dropped about 15mV instead of going up. Also found out that leakage current at 9V for germanium diodes should be in the range of 50uA instead of 5. Bummer.
Edit2: Measured leakage using a 1.35V battery and got 4uA which is too high for a Schottky. Maybe it's new production with better characteristics?
Pic of the diode:
(https://i.postimg.cc/5Y1wW2tr/IMG-20210212-144126344.jpg) (https://postimg.cc/5Y1wW2tr)
At higher current, the Vf does go up. Can reach 1v for some Ge. Si diodes can do this also. Schottky can equal ordinary Si junctions at higher current.
With glass Ge diodes, the point-contact structure can usually be seen...
(https://www.researchgate.net/publication/248556170/figure/fig4/AS:267711750078497@1440838863606/Point-contact-Ge-diode-1S32-Toshiba.png)
The path through a diode will have some ordinary resistance, so voltage drop over that will increase with higher current and add to the apparent Vf.
.
>35k in reverse
that could be realistic, i have some real vintage AA119 diodes, they read 1.8Mohm in reverse, despite being Ge, that could just be up to the DMM
i did measuere reverse leakage at 10v with a 100k trim pot, i read about 5v over the diode, when the pot reached 24k
some Ge's leak more, some less.
schottkeys on the other had had OL readings on the highest settings, and had 0v when using a 10M resistor at 10v.
cheers, Iain
With glass Ge diodes, the point-contact structure can usually be seen...
(https://www.researchgate.net/publication/248556170/figure/fig4/AS:267711750078497@1440838863606/Point-contact-Ge-diode-1S32-Toshiba.png)
[/quote]
I've added a pic to my post. Can't get bigger closeup but I don't see that thin bendy wire when using a magnifier.
"In a small silicon diode operating at its rated currents, the voltage drop is about 0.6 to 0.7 volts. The value is different for other diode types—Schottky diodes can be rated as low as 0.2 V, germanium diodes 0.25 to 0.3 V, and red or blue light-emitting diodes (LEDs) can have values of 1.4 V and 4.0 V respectively."
Here are 3 picture of 3 diodes, one is a real 1N34A. Others 1N914 1N4005
(Note on the meter Uf should be Vf and the symbol is reversed. (correct me if this statement is not correct))
(https://i.postimg.cc/XpY7Bgyj/1-N34-old.jpg) (https://postimg.cc/XpY7Bgyj)
(https://i.postimg.cc/jL3qHJzz/1N4005.jpg) (https://postimg.cc/jL3qHJzz)
(https://i.postimg.cc/jDWxZdXB/1N914.jpg) (https://postimg.cc/jDWxZdXB)
Quote from: Phend on February 12, 2021, 10:47:19 AM
"In a small silicon diode operating at its rated currents, the voltage drop is about 0.6 to 0.7 volts. The value is different for other diode types—Schottky diodes can be rated as low as 0.2 V, germanium diodes 0.25 to 0.3 V, and red or blue light-emitting diodes (LEDs) can have values of 1.4 V and 4.0 V respectively."
Here are 3 picture of 3 diodes, one is a real 1N34A. Others 1N914 1N4005
(Note on the meter Uf should be Vf and the symbol is reversed. (correct me if this statement is not correct))
(https://i.postimg.cc/XpY7Bgyj/1-N34-old.jpg) (https://postimg.cc/XpY7Bgyj)
(https://i.postimg.cc/jL3qHJzz/1N4005.jpg) (https://postimg.cc/jL3qHJzz)
(https://i.postimg.cc/jDWxZdXB/1N914.jpg) (https://postimg.cc/jDWxZdXB)
Uf is absolutely scinetifically correct, the symbol for electrical tension is U. english is one of the few languages where tension is replaced by the word voltage, but that's technically incorrect.
cheers
Quote from: Phend on February 12, 2021, 10:47:19 AM
"In a small silicon diode operating at its rated currents, the voltage drop is about 0.6 to 0.7 volts. The value is different for other diode types—Schottky diodes can be rated as low as 0.2 V, germanium diodes 0.25 to 0.3 V, and red or blue light-emitting diodes (LEDs) can have values of 1.4 V and 4.0 V respectively."
AFAIK, Ge diodes can vary A LOT with a Vf value - from 0.2 to 0.8V. I have a lots of them, some bought in Russia, some in China, they are definitely Ge diodes (according to the package and that you can actually see point contact inside), but they vary a lot. So it is always good to measure, or even better, to socket them and listen how they sound in a particular circuit.
Not all Ge diodes have the "cats whisker" point contact. There are other methods that are not so obvious.
I have some old Si diodes that look like what you have, but I can tell by the Vf they are definitely silicon.
Old semiconductors were either in glass or metal. I could be wrong, but I wouldn't expect to find Schottky diodes in the larger bottle glass casing - they are comparatively recent aren't they?
Quote from: Phend on February 12, 2021, 10:47:19 AM
Here are 3 picture of 3 diodes, one is a real 1N34A. Others 1N914 1N4005
(Note on the meter Uf should be Vf and the symbol is reversed. (correct me if this statement is not correct))...
Symbol IS correct. (Though parallax makes it hard to tell 1 from 2 on the socket.) Stripe on diode is line on symbol.
QuoteI've added a pic to my post. Can't get bigger closeup but I don't see that thin bendy wire when using a magnifier.
It looks like a solid "bar" inside instead of the wiggly wire like the pic anotherjim posted.
I've been doing electronics a long time and I've never seen a diode like that, not with the clear glass and "real germanium case" styling. I'm thinking it's a Schottky with a casing designed to deceive. The measurements look more like Schottky.
Quote(Note on the meter Uf should be Vf and the symbol is reversed. (correct me if this statement is not correct))
Europeans have used U for voltage for a *long* time and everyone else uses V. Both are correct, maybe think of the U as V with a European accent. The IEC standards will push for U as they are fundamentally European.
EDIT 1:
Here's some yabbering on the topic,
https://electronics.stackexchange.com/questions/99584/where-does-u-for-voltage-come-from
EDIT 2:
It's possible the odd casing is the same as a photo-diode.
Quote from: rankot on February 12, 2021, 02:59:01 PM
Quote from: Phend on February 12, 2021, 10:47:19 AM
"In a small silicon diode operating at its rated currents, the voltage drop is about 0.6 to 0.7 volts. The value is different for other diode types—Schottky diodes can be rated as low as 0.2 V, germanium diodes 0.25 to 0.3 V, and red or blue light-emitting diodes (LEDs) can have values of 1.4 V and 4.0 V respectively."
AFAIK, Ge diodes can vary A LOT with a Vf value - from 0.2 to 0.8V. I have a lots of them, some bought in Russia, some in China, they are definitely Ge diodes (according to the package and that you can actually see point contact inside), but they vary a lot. So it is always good to measure, or even better, to socket them and listen how they sound in a particular circuit.
i have noticed the HUGE range of forward voltages as well, i have Ge's measuring up to 1.1v in my power diode stash. weird package, one lead and a threaded metal case.
QuoteEuropeans have used U for voltage for a *long* time and everyone else uses V. Both are correct, maybe think of the U as V with a European accent. The IEC standards will push for U as they are fundamentally European.
the Europeans have used U for tension/potential since before the Edison decided it was cool to not use the global standards.
south America, Africa and large parts of Asia also use U, the Brits and US are the odd ones out, at first using T instead of U, and then transitioning to V in the 1880's.
cheers, Iain
Here's what we are dealing with,
(https://1.bp.blogspot.com/_tN7GiGTkw4Y/SI_ZFEpLxSI/AAAAAAAAA8I/GZW9w1uthhk/s400/diodo+germanio.jpg)
From
https://www.forosdeelectronica.com/threads/amperimetro-para-medir-potencia-de-un-transmisor.14897/
That sparked my memory, there's diodes call "Hot Carrier" diodes which came in a lot of odd casings. They are basically a form of Schottky diode.
Quotethe Europeans have used U for tension/potential since before the Edison decided it was cool to not use the global standards.
south America, Africa and large parts of Asia also use U, the Brits and US are the odd ones out, at first using T instead of U, and then transitioning to V in the 1880's.
When I was a kid I had a lot of databooks/brochures/catalogues/publications from Siemens so I'm used to the European style and symbols. When you deal with electro-acoustics the electrical V symbols are good because they don't clash with u and U symbols for velocity and Volume velocity.
Quote from: Rob Strand on February 12, 2021, 05:09:07 PM
QuoteI've added a pic to my post. Can't get bigger closeup but I don't see that thin bendy wire when using a magnifier.
It looks like a solid "bar" inside instead of the wiggly wire like the pic anotherjim posted.
I've been doing electronics a long time and I've never seen a diode like that, not with the clear glass and "real germanium case" styling. I'm thinking it's a Schottky with a casing designed to deceive. The measurements look more like Schottky.
You're probably right. Using a magnifier they do look like a junction diode and I don't see anything that resembles the cat whisker of a point contact diode. However, I've read that junction diodes were sometimes made with germanium so maybe these are like that. The leakage currents seem to be in the range expected from germanium. A long maybe but with a bit of luck these are germanium junction diodes with some of the desirable germanium properties at stompbox voltages. I don't know, I'm just brain storming.
I got some more stuff incoming, including breadboards and parts, some schottky diodes and a pair of expensive point contact 1N34A's from a reputable music store. I'll built a small circuit to test them using a range of small forward and reverse voltages (10-500mV) and see if the I-V curves at stompbox voltages look like Schottky's or more like real 1N34A.
QuoteUsing a magnifier they do look like a junction diode and I don't see anything that resembles the cat whisker of a point contact diode. However, I've read that junction diodes were sometimes made with germanium so maybe these are like that. The leakage currents seem to be in the range expected from germanium. A long maybe but with a bit of luck these are germanium junction diodes with some of the desirable germanium properties at stompbox voltages. I don't know, I'm just brain storming.
It's possible to make diodes like that but I just haven't seen any.
It's actually an interesting dilemma What measurements can we make to determine if it's Germanium or Schottky? Why do we care, what characteristic makes the difference, and if there is a difference why can't we measure it!
One difference is the incremental slope of the V vs I curve. Probably need to cover 1uA to 10mA.
Normally we can see a difference between the two diode types at a test current of 10mA. The funny thing is not many circuits actually push the diodes that hard. It's just a convenient test to see the difference.
I had some thoughts that the band-gap voltage of silicon and germanium are different, which shows up in temperature tests. However, Schottkys aren't exactly like silicon and the effective band-gap voltage ends up being a lot like germanium. Reverse recovery is another difference but it needs a very careful set-up of the experiment, probably not practical for hobbyists.
If I wanted to get a germanium diode that would not be likely to be counterfeit, I would select a 1N295 which was the standard detector diode for transistor radios, both AM and FM, and forget about the 1N34 and all its variations. Many of these diodes have the colour code (red, white, green) on the cathode end serving as the cathode band, so it is hard to get confused.
The 1N60 was the standard video detector diode for televisions for a couple of decades and these are low-capacitance, low forward current devices.
I also have a stash of devices labelled "germanium" with forward voltages in the 0.6 to 0.7 range, so either deceit or confusion has caused this to happen. I also have some in the 0.27 to 0.35 range that I believe are germanium, so measurement is your best protection against fakes.
Picture of a 1N34A that I have. Also it being measured, both directions, in cheap tester.
Note black band on diode and symbol on tester. No big deal.............
(https://i.postimg.cc/Xr7snV3s/IMG-7238.jpg) (https://postimg.cc/Xr7snV3s)
(https://i.postimg.cc/SXnVzDn8/IMG-7240.jpg) (https://postimg.cc/SXnVzDn8)
(https://i.postimg.cc/v1Ch7fnK/IMG-7242.jpg) (https://postimg.cc/v1Ch7fnK)
Original picture i can see the corrosion on the leads, usually old stock does that. I have hundreds of old germanium diodes and also hundreds of old silicon, all from the 50-60's from my dads tv shop. I don't think i have a schottky here to compare. I'm going to pull out my old Hickok germanium transistor tester. It measures a lot of parameters for transistors and i know there is a section in the book on diodes, will have to see what i can measure. There are usually color coded bands but i have seen many japanese diodes i scrapped from radios that i know are germanium but are clear glass.
The bottom of this page has some measurements of the diode "slope" parameter "n". The results are done at very low currents.
https://www.lessmiths.com/~kjsmith/crystal/dpiii.shtml
You can see the n for Schottky's tends to have n < 1.2 and germaniums have n > 1.2. If you test at higher currents you should see a similar pattern. "n" affects the softness of the clipping.
There's also this type of diode (the geranium diode) which tends to flourish this time of year. The only diode that doesn't smell bad when the smoke gets out.
(https://farm2.staticflickr.com/1589/23594985344_c752b64a97.jpg)
"What did you get for your Valentines gift?"
"A diode." :icon_confused:
Ok, but testing when you get them is a little late in the game. It would help to know how to judge the listing.
We know that some suppliers consider Schottky to be equivalent/replacement for obsolete germanium. If you search for a germanium part, it could well offer Schottky in this belief.
We also know that you can't trust the photo of the offering to be correct. Very often it's any picture of any diode that was handy.
We probably do know what the price of the offering is. If it's at mass-produced silicon prices, then that's probably what it is.
Anyone using the ones NTE sells, either direct or through digikey? ~$0.70/each. Seem to be new
I got some recently and their Vf is fine, but I haven't done any further checking or testing.
I'm wondering if they're schottky.
(https://i.postimg.cc/WF2B7vjS/IMG-20210214-150225.jpg) (https://postimg.cc/WF2B7vjS)
Quote from: mark2 on February 14, 2021, 04:06:52 PM
Anyone using the ones NTE sells, either direct or through digikey? ~$0.70/each. Seem to be new
I got some recently and their Vf is fine, but I haven't done any further checking or testing.
I'm wondering if they're schottky.
(https://i.postimg.cc/WF2B7vjS/IMG-20210214-150225.jpg) (https://postimg.cc/WF2B7vjS)
Those seem to be Ge.
we can discuss whether or not diodes are true Ge or if they are fake/schottky... but i wonder 'if' and/or 'how much' it actually matters.
in a clipping situation, i couldn't tell you in a blind test if they are Ge or schottky, i used to be convinced i could, but after doing blind testing, i can't.
some germaniums sounded harsher and some softer, while the schottky diodes were generally more middle of the road, but they too had types that are softer or harder.
i don't want to stirr up a heated debate like those you can find on gear forums, but i like to hear other peoples experiences and opinions.
cheers, Iain
Quote from: mark2 on February 14, 2021, 04:06:52 PMAnyone using the ones NTE sells, either direct or through digikey? ~$0.70/each. Seem to be new....
NTE has been doing business for 42 years. (https://www.nteinc.com/about-nte.php) Their stuff has very long shelf life; until last year I could go into Greenbrook Electronics and find ECG/NTE parts from the last century. I don't know that old diodes are surely fresher from DigiKey or NTE itself.
I finally got my orders from China in and did some measurements. I made a simple test rig with a 9V battery, a 10k pot + 40 ohm resistor as a voltage divider. It's not good to test higher currents but I was mainly interested in the slope and smoothness of I-V curve at lower values anyway.
The moderately priced 1N34A mentioned before are called 1N34A-M in the figure. I tested 3 of those but the values were very similar so I just averaged them.
I got 2 expensive 1N34A, that had the cat whisker and all, in the figure they are called -E1 and -E2.
I also got a some cheap "1N34A" that were not see-through but orange (-C). I bought them together with some "germanium" 1N60 that had similar packaging except for some small print on the glass. The V-I curve of all these diodes were the same, so probably all the same diodes but a few with the print rubbed off. I also tested a few BAT41's and silicone 1N4148's for reference.
The moderately priced 1N34A and the cheap 1N34A and 1N60 are probably all Schottky diodes as their V-I curves are at low voltages and steep. The expensive 1N34A's had a different curve as the others, but the slope was very flat and the red one (-E1) really had lower current at the highest voltage. At 600mV the conduct similar amounts as a silicone diode which seems wrong. They are probably real 1N34A but just not very good ones >:(
(https://i.postimg.cc/B8H2kNCN/diode-test.jpg) (https://postimg.cc/B8H2kNCN)
i want to get my hands on diodes which have that red curve, might give some cool semi-wave-folding grind especially if the curve goes down further at that rate.
to bad you got some bad / semi-fake diodes, but the real question is; which sound better to you?
or do they just have different characters which are good for different types of distortion? even better yet, how do they sound together in asymmetric clipping???
cheers
QuoteThe moderately priced 1N34A mentioned before are called 1N34A-M in the figure. I tested 3 of those but the values were very similar so I just averaged them.
I got 2 expensive 1N34A, that had the cat whisker and all, in the figure they are called -E1 and -E2.
I also got a some cheap "1N34A" that were not see-through but orange (-C). I bought them together with some "germanium" 1N60 that had similar packaging except for some small print on the glass. The V-I curve of all these diodes were the same, so probably all the same diodes but a few with the print rubbed off. I also tested a few BAT41's and silicone 1N4148's for reference.
The orange package ones are likely to be Schottkys. I've got a lot real germaniums which sit around the same voltages as the Schottky until you get to 1mA where it starts to deviate and by 10mA the difference between the germaniums and Schottkys is clear.
The -E1 and -E2 curves look very different. Perhaps more different to what I generally see. I'd have to pull out some very old stuff to see if any were like those. Unfortunately I thew out most of my old original Ge's a *long* time ago.
FWIW, your 1N4148 curve looks a bit different to what I'm used to.
The BAT41's looks a bit high as well.
Data sheet is 260mV @ 100uA and 360mV @ 1mA.
My BAT46's were 200mV @ 100uA and 270mV @ 1mA.
You curve is 260mV @ 100uA but is aiming at 540mV @ 1mA; looks like quite a bit more series resistance, like 180 ohms!
Quote from: PRR on February 14, 2021, 09:06:21 PM
Quote from: mark2 on February 14, 2021, 04:06:52 PMAnyone using the ones NTE sells, either direct or through digikey? ~$0.70/each. Seem to be new....
NTE has been doing business for 42 years. (https://www.nteinc.com/about-nte.php) Their stuff has very long shelf life; until last year I could go into Greenbrook Electronics and find ECG/NTE parts from the last century. I don't know that old diodes are surely fresher from DigiKey or NTE itself.
Don't forget Masters
Quote from: iainpunk on March 07, 2021, 06:58:18 PM
i want to get my hands on diodes which have that red curve, might give some cool semi-wave-folding grind especially if the curve goes down further at that rate.
to bad you got some bad / semi-fake diodes, but the real question is; which sound better to you?
or do they just have different characters which are good for different types of distortion? even better yet, how do they sound together in asymmetric clipping???
cheers
True, the real question is how they sound. I'll just try them all and see what I like best.
Quote from: Rob Strand on March 07, 2021, 07:47:39 PM
QuoteThe moderately priced 1N34A mentioned before are called 1N34A-M in the figure. I tested 3 of those but the values were very similar so I just averaged them.
I got 2 expensive 1N34A, that had the cat whisker and all, in the figure they are called -E1 and -E2.
I also got a some cheap "1N34A" that were not see-through but orange (-C). I bought them together with some "germanium" 1N60 that had similar packaging except for some small print on the glass. The V-I curve of all these diodes were the same, so probably all the same diodes but a few with the print rubbed off. I also tested a few BAT41's and silicone 1N4148's for reference.
The orange package ones are likely to be Schottkys. I've got a lot real germaniums which sit around the same voltages as the Schottky until you get to 1mA where it starts to deviate and by 10mA the difference between the germaniums and Schottkys is clear.
The -E1 and -E2 curves look very different. Perhaps more different to what I generally see. I'd have to pull out some very old stuff to see if any were like those. Unfortunately I thew out most of my old original Ge's a *long* time ago.
FWIW, your 1N4148 curve looks a bit different to what I'm used to.
The BAT41's looks a bit high as well.
Data sheet is 260mV @ 100uA and 360mV @ 1mA.
My BAT46's were 200mV @ 100uA and 270mV @ 1mA.
You curve is 260mV @ 100uA but is aiming at 540mV @ 1mA; looks like quite a bit more series resistance, like 180 ohms!
It was pretty quick and dirty and I'm sure my simple test rig gets unreliable with higher currents. Up to 200-300 uA it's probably ok, but I wouldn't trust the accuracy above it. The point of adding the BAT41 and 1N4148 was to have something to compare to but more in a relative way than in an absolute way.
I just had a closer look at the data-sheet characteristics of small-signal germanium diodes once made by Intermetall, Siemens, Telefunken, and Valvo/Mullard between the 1950s and 1980s. The considered diodes are from the AA and OA series. Similar germanium diodes from other manufacturers shouldn't differ significantly from these types, though.
First of all, it is important to note that there are actually two basic types of germanium diodes, namely point-contact diodes (which, physically, are Schottky barrier diodes) and ordinary junction diodes. The germanium point-contact diodes can be further subdivided into the following two subtypes:
– Germanium point-contact diodes of the non-welded contact type
– Germanium point-contact diodes of the welded contact type
As the internal construction of these two subtypes is virtually identical, a visual distinction is next to impossible—yet their electrical characteristics are quite different! Provided that my considered set of 20+ diodes is sufficiently representative, germanium point-contact diodes of the non-welded contact type, which seem to be of primary interest here, should nevertheless be safely distinguishable from silicon junction and Schottky barrier diodes and also from other types of germanium diodes.
To the best of my knowledge, all germanium diodes from AA111 to AA134, the AA137/138, and the AA140/142 are point-contact diodes of the non-welded contact type, as are all OA types from OA50 to OA95 and from OA150 to OA179, plus a few more. Similarly, all 1N types from 1N34 to 1N75 (except 1N53), from 1N86 to 1N90, from 1N111 to 1N117, and from 1N119 to 1N128 belong to this class, too. Examples of germanium point-contact diodes of the welded contact type (also denoted as gold-bonded diodes in some data-sheets) are the AA135 and AA143/144, whereas the AA136 and AA139 are germanium junction diodes.
In short, identifying germanium point-contact diodes of the non-welded contact type basically requires cautious measurements of the forward currents at 500 mV and 1 V forward voltage drop and of the leakage current at 2–5 V reverse voltage, all at 25°C junction temperature. Besides, all diodes in DO-35 or similar glass cases (like the 1N4148) can be completely ruled out anyway; all small-signal germanium point-contact diodes I've ever seen use considerably larger packages such as the DO-7 glass case.
The measurement temperature of 25°C is an important factor here since the forward and in particular the reverse characteristics of germanium diodes vary significantly with the temperature. For instance, the leakage current of the collector-base junction of germanium transistors at medium reverse voltages approximately doubles with every 10°C increase in junction temperature!
To get around such temperature effects, any internal heating of the junction must be kept as small as possible during the measurements. For the forward-current measurements, this means that the active measurement time must be kept short (e.g., by using pulsed operation with no more than 2% duty cycle) and the device must be given enough time to cool down after each measurement. Moreover, in order not to damage the device under test, all currents must be strictly limited to 15–20 mA, no matter whether the above two forward voltages can be met or not.
With this, the typical forward current of a small-signal germanium point-contact diode of the non-welded contact type should then lie between, say, 3 mA and 15 mA at 1 V and roughly 25% of this value at 500 mV; this rather flat forward characteristic is probably responsible for the very specific sound when such diodes are being used for smooth clipping. And when, in addition, the leakage current at reverse voltages of 2–5 V is safely greater than a few hundred nano-ampere, there is a pretty good chance to have indeed such a germanium point-contact diode at hand.
In contrast, germanium point-contact diodes of the welded contact type (gold-bonded diodes), germanium junction diodes, and most silicon Schottky barrier diodes usually reach forward currents in excess of 10 mA already at, or even well below, 500 mV forward voltage drop, whereas silicon junction diodes will just enter the conduction region at this voltage. Additionally, the leakage current of silicon junction diodes at reverse voltages of 2–5 V will usually be much smaller than 100 nA.
One minor, remaining problem with this approach, however, can be that all these old germanium diodes revealed significant variations in their actual characteristics, so that a definitive distinction can nevertheless be rendered difficult in some cases.
I hope this helps to clarify this basic issue.
In a forthcoming post, I'll address the in-circuit emulation of germanium point-contact diodes of the non-welded contact type using dedicated circuits with two or more silicon Schottky barrier diodes and a few additional resistors. This will probably be a more economical and also more reliable way to deal with this whole subject.
There were some pics around of diodes which have the longer glass casing like germaniums but they are zeners. For example old 1N746A through 1N75xA and 1N4370A to 1N4372A. I still have quite a few of these.
The difference is they don't have the wiggly wire inside like the true germaniums shown reply #25,
https://www.diystompboxes.com/smfforum/index.php?topic=126386.msg1208968#msg1208968
They have a solid internal structure, like this, (same look as Reply #35).
(https://i.postimg.cc/Lh2Qmxtz/zener-1n4370-A.jpg) (https://postimg.cc/Lh2Qmxtz)
Also when you measure them in the forward direction it should be quite obvious they measure like a silicon diode.
QuoteThere were some pics around of diodes which have the longer glass casing like germaniums but they are zeners.
That's not the point. What I wanted to express is that there are no genuine germanium point-contact diodes in such small glass cases as, for example, the DO-35 case.
QuoteThe difference is they don't have the wiggly wire inside like the true germaniums shown [in] reply #25
The fundamental drawback with this wiggly wire (or 'cat whisker') is that this is, of course, a necessary condition for point-contact diodes, yet not a sufficient condition for point-contact diodes of the
non-welded contact type—and these are the diodes which are of interest here!
By the way: I was a bit lazy in this respect when describing the three types of germanium diodes. In fact, only the point-contact diodes of the non-welded contact type are Schottky barrier diodes, physically. The welding process forms a tiny P region in the N-type crystal around the original point contact which, in effect, transforms the point-contact diode into a junction diode with completely different electrical characteristics. See:
– https://en.wikipedia.org/wiki/Diode#Point-contact_diodes (https://en.wikipedia.org/wiki/Diode#Point-contact_diodes)
– https://www.richis-lab.de/Diode05.htm (https://www.richis-lab.de/Diode05.htm)
Since semiconductor junctions can be light-sensitive, many of these old, glass-encapsulated germanium devices, diodes as well as transistors, were painted black to protect the interior from light. But even if one scratches off the black painting and finds such a wiggly wire, it's still next to impossible to distinguish between welded and non-welded types. At least something like a microscope would be needed to see artefacts of the welding process in the close vicinity of the point contact (last image on Richi's Lab page); non-welded types do not have such a welding bead. All in all, this is not really a practical option.
The only sufficiently reliable method to identify germanium point-contact diodes of the non-welded contact type is therefore to perform the described measurements, even if the given range of forward currents (i.e., 3–15 mA at 1 V forward voltage drop and roughly 25% of this measured value at 500 mV) is just a best guess of what ought to be found. Slightly lower values might be possible for some diodes, though.
Are these diodes original? As far as I know, TME is a serious company and I don't think it messes with fakes, and I was curious if these diodes are really 1n34a because I know they can't be found anymore. https://www.tme.eu/en/details/1n34a-nte/diodes-others/nte-electronics/1n34a/