Component Identification

[Peterae]

Blimey ION sounds like you could open a museum or make a killing on eBay, when i type 'diode 1s' into eBay very little comes up. 

[poynt99]

Here's a better shot of those diodes.

.99

[Peterae]

Darren
Not sure if you have seen my earlier post 29, but that diode package is shown on the datasheet and there are also single package diodes with VF of 0.9V, the only problem is that i could not find the whole data book which identifies which diodes use package 30.

So it is probably silicon and a single diode and probably a 1S series diode, what is needed is the 1993 whole data book and it would be easy to identify which diodes use that package.

http://www.overunityresearch.com/index.php?topic=1162.msg17954#msg17954

[poynt99]

Hi Peter, and thanks for helping out here.

V_F specs given in the tables of datasheets are for the maximum value only. This value does not reflect real world applications, and is typically much lower (0.3V for Ge for eg.). The V_F(max) given in most specs sheets for germanium diodes is 1V, so all of those diodes in the datasheet you pulled up could be germaniums.

Using a voltmeter set on the "diode" measurement setting is going to use a relatively small forward current, so the measurement produces V_F's much lower than the max value they publish. V_F(max) is not a very useful spec imho.

Darren

[ArtistGuy]

Poynt,

I'm in contact with a retired electronics whiz about this...was wondering if you can supply an image of the bottom (traces, etc) too?

He says he can (likely) tell what (kind) they are simply by how they are connected, and to what.

Robert

[poynt99]

No problem Robert.

I am pretty sure they are connected back-to-back in parallel across pins 1 and 2 of the op-amp. In other words, they are in the feedback loop of the op-amp. The other two more familiar-looking diodes are also in parallel in the fb loop, but with a series resistor as well.

So the pair with the series resistor conduct first (assuming the measured 0.58V VF is correct, i.e. a Si pair), but they only limit a little due to the series resistance. This begins the gentle limiting of the over all transfer function. Then a package of 3 or 4 series Ge diodes (two packages in anti-parallel) with a VF of about 0.9 V begin to conduct some time after the first pair, but these conduct fully. "Fully" for Ge diodes means they reach a limiting point, but this point forward is a softer limiting function than Si diodes, and hence the difference in sound and intensity of harmonics produced.

Anyway, here is the bottom side of that pcb, if it helps. I haven't compared it to the other pics I posted, but I'm sure it is the same pcb/circuit.

Thanks,
.99

[the_big_m_in_ok]

I'd never heard of the cats whisker until i watched th series ION posted, story of electricity, what a marvellous doc for Us The Uninitiated

I can't believe the transistor used to be a big thing that looked like a spider that had been in an accident !

DeepCut...
Very accurate, as I see it...

www.don-lindsay-archive.org/talk/transistor.html

Does it look like a transistor or a squished spider?      

--Lee