[sdiy] Pin Outs

[Oren Leavitt]

David Ingebretsen wrote:
> I am not finding a data sheet (well, at least one with any extensive info)
> or pin-outs for a couple of obsolete parts.
> 
> 2N5163 n channel jfet
> 2n4891 UJT
> 
> The basic question is, is there a "hand test" I can do to determine the
> pin-out for sure?
> 
> I have a simple circuit I could breadboard for the UJT, but nothing really
> for the JFET.
> 
> I have some "replacement" parts which have appropriate pin outs printed on
> the envelope they came in, but I also have some of the original vintage
> parts which I would rather use.
> 
> The component packages between the original parts and the replacements are
> different subtly.
> 
> To complicate matters, I have two vintage version of the 2n5163, in similar
> but different packages, one is a TO-106 I think with a flat side by one pin,
> one does not have a flat on it at all.
> 
> JFET:
>                            .   apex
> Pins are in a triangle   .   .   base of triangle
> 
> Package 1: TO-106(?) round with round top flat is offset adjacent to one of
> the pins (vintage)
> 
>                         .
>                  Flat .   .
> 
> Package 2: TO-106(?) round with round top, flat opposite middle pin,
> parallel to base of the triangle (new replacement)
> 
> 
>                         .
>                       .   .
>                        Flat
> 
> Package 3: TO-106(?) round with round top, no flat (vintage)
> 
> UJT
> 
> Pins are in a triangle, metal housing with a tab
> Package 1: TO-18(?) tab between triangle apex pin and a triangle base pin
> (new replacement)
> 
>                     .
>               tab .   .
> 
> Package 2: TO-18(?) tab at an angle, but is between the two triangle base
> pins.
> 
>                     .
>                   .   .
>                   tab
> 
> I found some old schematics which suggest two different pin-outs for the
> JFET, Source, Gate, Drain, and Source, Drain, Gate, both suggesting a TO-106
> round top package was used, but I'm not sure.
> 
> I have struck out completely on the UJT. Believe me, I have searched every
> internet datasheet archive I could find.
> 
> I have a simple schematic for the UJT which I guess I can breadboard and try
> the replacement I know the pin-out for and then try an old part to see. But,
> I'm a bit at a loss for the JFET.
> 
> Thanks
> David
> 
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> 

David,

I do have data for the 2N4891 UJT in a 1973 copy of the TI Transistor 
and Diode data book.
This shows a plastic package with this pin out (bottom view):
 >                      Emitter
 >                         .
 >                  Base2.   .Base1
 >                        Flat

You should be able to test it with a simple relaxation oscillator.
I can send you a scan of the data pages if you wish. There are 
test/measurement circuits provided.
The tab on your TO-18 version is likely between the emitter (middle) and 
base2 (side).

- Oren