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Author Topic: Component Identification  (Read 71094 times)

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It's not as complicated as it may seem...
Rusty gear sounds better ;)

I'll be posting that tune. I need to buy some adapters so I can run my cassette deck into my sound card. I'll be picking those up tomorrow. ;)

Darren
   

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It's not as complicated as it may seem...
Just an FYI,

The simplest way to use two zeners for this application, is to connect them in series, back-to-back in the fb loop of the op-amp. The two components in question in this circuit are in parallel in the fb loop, and in such a case, they would perform as "normal" diodes only.

.99
   

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I am amazed that the component in question has not been identified, I've looked for stacked diodes, limiter diodes and scanned pictures of older case styles and have not seen anything like it, and yet they obviously went to the trouble of putting them into production.
   
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Here's a thread that talks of germanium diodes in early fuzzboxs:

http://archive.ampage.org/threads/1/fxgd/000105/Germanium_diodes_color_code_-1.html


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Ha ha getting closer

Look at this datasheet but it's only got page 150  :'(, Theres a diode with a V Forward of 0.9 and at the bottom it shows the diode package 30 we want. O0

EDIT what we need is the rest of an old diode selection guide, i am now suspecting it's a single diode but with 0.9V forward but is it silicon or germanium.
   
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.99

The only time I ever had seen such a diode was in a power supply from around 1970,
and it was a low voltage Zener.

Most low voltage Zener diodes has a forward voltage of 0,9 to approx. 1 volt.
So if you put two back to back in parallel then you get exactly what you want
in clipping voltage.

GL.
   
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It looks like you may have what was called a low leakage diode. If so, you can duplicate the operation by replacing it with a common small signal NPN transistor using only the base and collector leads.

A 2N3904 should provide about .7V. Add a small resistor in series to bring it up to .9.

I haven't tried that trick in a while. Normally, I would use some 1N34A's.

   

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It's not as complicated as it may seem...
.99

The only time I ever had seen such a diode was in a power supply from around 1970,
and it was a low voltage Zener.

Most low voltage Zener diodes has a forward voltage of 0,9 to approx. 1 volt.
So if you put two back to back in parallel then you get exactly what you want
in clipping voltage.

GL.

This is what I measured today with my meter:

- 1N4148 VF = 0.58V (as expected)
- 1N34A (Germanium) VF = 0.24V
- 2.4V, 2.7V, 3.3V Zeners VF = 0.66V
- 4x 1N34A Ge's in series VF = 0.93V

.99
   
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This is what I measured today with my meter:

- 1N4148 VF = 0.58V (as expected)
- 1N34A (Germanium) VF = 0.24V
- 2.4V, 2.7V, 3.3V Zeners VF = 0.66V
- 4x 1N34A Ge's in series VF = 0.93V

.99

Different diode types are characterized at different forward currents. What current are you using?


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It's not as complicated as it may seem...
I was using a meter on the "diode" setting, so I assume they were all tested at the same current, which is what we want in order to compare VF's for application in a clipping circuit.

This is also most likely how that person on the forum made the measurements he posted.

.99
   
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It's turtles all the way down
I was using a meter on the "diode" setting, so I assume they were all tested at the same current, which is what we want in order to compare VF's for application in a clipping circuit.

This is also most likely how that person on the forum made the measurements he posted.

.99

True, but when comparing with info on data sheets, you should use the forward test current specified. Temperature also affects forward drop.


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It's not as complicated as it may seem...
So here's that song, Nov, 1984:

A friend (bass player) had some friends (vocalist and guitarist) from the University of Alberta that got together and wrote a song called "Set Fire". My friend and I were jamming with this green jazz drummer at the time, so they all came over to my place and in an afternoon we recorded this song on a 4-track cassette machine for entry into the local rock station's battle of the bands or something to that effect.

My part was to play only the lead guitar. I did one take. My friend the bass player was getting into popping and slapping technique and I suppose he figured this song suited that style.....I didn't think so...judge for yourself. We are off time and the vocalist can not be understood, nor could he sing that well imho. We also had no equipment to speak of (all guitars went direct I think), and the echo was my Boss Analog Delay.

Anyway, it is kinda bad, but we had fun doing it. I'm sure when folks heard this song on the radio they were agreeing with the chorus line of "set fire to me" LOL.

One day shortly thereafter, I was waiting at a place of business to pick something up and suddenly our song came on the radio playing in the reception area....cool  8)

 :-[
.99
   

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.99,

Not bad at all!  Better in fact than much of what is
heard today from some of the so-called "stars."

Can you tell us more about the lyrics?  How should
we interpret them?

It would seem that the mystery components have at
last been identified.  Germanium stacks (and silicon
too) were used in biasing complementary output
stages to minimize crossover distortion.  Creative
minds found other interesting uses for them also.

One must wonder how the Fuzz circuit would work with
LEDs in place of the 0.9 Volt Germaniums...


Here's a page
with circuits and explanations.


.99,
I see the difference in Germanium (soft) and Silicon
(hard) clipping.  Yes, LEDs would clip at a higher amplitude.
« Last Edit: 2011-10-28, 04:48:02 by Dumped »


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It's not as complicated as it may seem...
Thanks Dumped.

I honestly don't remember exactly what the lyrics mean. Half of the words are unintelligible which makes even more difficult to figure out.

Germanium stacks, yes, but did they come in a single package like that? Later someone figured out how to do the biasing better with a Vbe multiplier, i.e. a transistor.

LED's clip quite hard (and at a higher amplitude) compared to diodes and germaniums, so I like to use them as a "top clip" in combination with a lower threshold and softer clipping diode.

.99
   
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Later someone figured out how to do the biasing better with a Vbe multiplier, i.e. a transistor.

.99,

Seriously? Forgive me but I'm more an RF guy and not so much into pn junctions either but wouldn't a Vbe multiplier just be a constant current source? And, heavily dependent upon temperature?

I hope the designs graduated from that method. If it was the same as RF there would be problems with thermal delay, age variations, mismatch between relative temp coefficients, etc.

I suppose folks like Peterae are just burning the functions as firmware now  :)
   
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Nice job on the tune. I played it very early this morning and I know it's gonna stick in my head all day, and that's a good thing, that's what record producers want. Could have been on the chart's.

I have only one song that ever received airplay, a spoofy country lament about a farmer whose wife tore down the old outhouse and had installed indoor plumbing "cold porcelain seats and all" while he was out plowin' the high field.

I think it was  played on the"Meatball Fulton" show back in '68, Philadelphia for his "Country Special (comedy) Hour". I never could write anything serious. Fotunately the tape was lost sparing you all any further agony.

On the subject of clipping, wayback I installed a 6AL5 miniature dual rectifier in my Fender Super Reverb for a clipping device. I used variable filament voltage to the tube to control the amount and shape of clipping.


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It's not as complicated as it may seem...
.99,

Seriously? Forgive me but I'm more an RF guy and not so much into pn junctions either but wouldn't a Vbe multiplier just be a constant current source? And, heavily dependent upon temperature?

I hope the designs graduated from that method. If it was the same as RF there would be problems with thermal delay, age variations, mismatch between relative temp coefficients, etc.

I suppose folks like Peterae are just burning the functions as firmware now  :)

Indeed, it is essentially a current source and with the correct values, it supplies a "floating" bias voltage across the driver stage. Attach the transistor body to the output heat sink and set the values correctly, and you have near perfect tracking of the bias voltage/current as the finals heat and cool. So temperature variation/tracking is precisely what you want.

.99
   

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It's not as complicated as it may seem...
Hi Vince.

Yeah the chorus can be a little catchy I guess.

Too bad you lost the song. I've lost some tapes too that I wish I had back from long ago.

How did your tricked-out Super Reverb sound?

Darren
   
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It's turtles all the way down
Hi Vince.

Yeah the chorus can be a little catchy I guess.

Too bad you lost the song. I've lost some tapes too that I wish I had back from long ago.

How did your tricked-out Super Reverb sound?

Darren

I think it sounded ok, but lacking some of the sweet harmonics of an external box. I made a number of other mods to that amp that probably destroyed its vintage resale value e.g.

Solid state rectifiers instead of 5U4. I used the leftover 5 volt winding as a power boost / buck (switchable) inserted into the primary.

Beefier power supply filtering.

Added individual bias pots and indicator leds so the bias could be precisely set for each output tube.

Beefed up the light gauge speaker wiring. Eliminated the problematic speaker jack in favor of hard wiring with solder connections to all speakers.

But it was pretty beat up physically when given to me

Added a channel switching relay (mercury wetted contacts) for the overdrive channel.

And all the usual mods. Still have it and it sounds fine. Am using a smaller Hot Rod Deluxe nowadays.


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I think you guys have some amazing talents and not just dam good in the electronics field.

It is unfortunate that most never manage to make a living from such talents, specially in the arts area, but when they do, what a life.
I have a friend who was a roadie for Led Zeppelin many years ago now, some of the stories he tells are amazing.

Thing is with anything to do with arts, you don't need to be really good, you just need good publicity and do stuff people like to hear or see.
Look at how much bad music is about and these peole make a living at it.

There's not much hope for me now, i keep forgetting things. it was Led Zeppelin not Thin Lizzy





« Last Edit: 2011-10-28, 19:03:19 by Peterae »
   
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I think you guys have some amazing talents and not just dam good in the electronics field.

It is unfortunate that most never manage to make a living from such talents, specially in the arts area, but when they do, what a life.
I have a friend who was a roadie for Thin Lizzy many years ago now, some of the stories he tells are amazing.

Thing is with anything to do with arts, you don't need to be really good, you just need good publicity and do stuff people like to hear or see.
Look at how much bad music is about and these peole make a living at it.
You bet, Peter...  The American rock group "Boston" started at MIT with engineering students, one of whom got his Master's there.

An announcement along those lines:
I've got a job coming up by Christmas working in the engineering field analyzing computer output data starting with, say, naval engineering.   This'll be classified, so that's all I'm going to say about it.

However, I would like to get more into music and electronic music in particular.   It might happen in a few years.

--Lee
   
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It's turtles all the way down
I made a very comfortable living in the electronics industry, but music has always been an amateur pursuit and I like it that way. (amateur: one who loves what they do)

Never much of a showman, I was always more interested in the personal side of music, it became sort of a way to journal what I was feeling  with a home studio. Nonetheless, I have been in many small time bands over the years and like to jam with the fellows now and then.

That mixed with a strong interest in the technical side has been an enjoyable life journey. I wouldn't have had it any other way.



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It's not as complicated as it may seem...
   
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Museum?

I thought those were the new models  ;D

Sticking the bias transistor on the heat sink was common in RF too. There were better ways which accounted for the other problems but I think all of that is mute with software based equipment.

   
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It's turtles all the way down
Peterae:

I feel really lucky, as I have nearly all of the diodes mentioned in that pdf.

don't have the cat whisker setup anymore tho


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