Hello Andrew,
Cool, thank you for elaborating on the matching procedure, this will
come in handy for fabricating the PNP/NPN replacements of this type,
probably also for other obsolete parts and where a compareable circuit
is used :)
---
Greetings,
Simon
(9-0-9)
On 2018-03-02 17:16, axmonti@yahoo.ca [PolySix] wrote:
> Hi 9-0-9,
>
> I've made plenty of replacements for the 2SA798 - just use two matched
> PNP transistors and place them back-to-back with their emitter tied
> together.
>
> Here are the transistors I use (I order at least 10 to end up with a
> matching pair).
>
> Here's the circuit you need to build (the PNP one) to match
> transistors. I recommend ordering two 0.1% resistors for your tester to
> avoid having to add a pot to make up the slight difference in
> resistance between the pair. You also have to have a +/- power supply
> (12-18V is fine) setup.
>
> The 2SA798 pinout is BCECB, so it's easy to tie the emitters together.
> Some people epoxy or zip-tie the transistors together, but they are
> pretty much exposed to the same temperature within an enclosed case, so
> I haven't found a need to perform that extra step.
>
> You can also use the same procedure to build 2SC1583 replacements; just
> use an NPN transistor such as this one (and flip the diode and power
> supply in the transistor matching circuit).
>
> Hope this helps!
> - Andrew
>
>
>
> -------------------------
> Posted by: axmonti@yahoo.ca
> -------------------------
