[personal] Re: Transistor Substitution

[Mike Hatch]

----- Original Message ----- 
From: "Tony Duell" <ard at p850ug1.demon.co.uk>
To: <cctalk at classiccmp.org>
Sent: Thursday, June 11, 2009 6:42 PM
>
> That's the easy case :-). You tend to remember the common transistors
> (2N2222, 2N3904, 2N3906, 2N2219, 2N2907) and look up the specs of those
> first (if you can't remember them).

If it helps anyone (probably in UK the most) there is a stock of old parts 
at - http://www.mclennan.co.uk/stockdisposalmenu.html - eg qty 3500 x 
2N3906, also with a few TTL and CMOS Ic's, all brand new.
I run that site, I'm not trying to advertise, but if there is anything there 
for list members let me know, I'll bypass the requirements at the top of the 
page, it's better you use the bits than they sit on the shelves.

Mike
Web - www.soemtron.org
PDP-7 - www.soemtron.org/pdp7.html
Email - mike at soemtron.org

Looking for a PDP-7 (some hope!)  and an ASR33

>
> What I used to do (I'll explain the 'used' in a minute) was based on the
> obvious fact that the substitute was only useful if I could get it. So
> I'd grab the catalogues for 2 or 3 suppliers and look down the list of
> transistors (normally only 2 or 3 pages) which included brief specs to
> see which would be suitable. If I was in doubt, I'd look up more detailed
> data on the couple of 'possible' devices.
>
> Why 'used to'? Well, you can't get paper catalouges from some suppliers
> any more. They expect you to use their web page. And I find it impossible
> to find transistors that way. The web pages were not set up by engineers,
> or even people remotely clueful in electronics. And you get some sillies
> (like some transistors being listed witha maximum collector current of
> 1A others 1000mA. Of course a search will find one and not the other...)
> I've kept paper catalouges from about 10 years ago, I look in those for
> suitable candidates and hope they're still available...
>
> -tony
>
>
>
>