[sdiy] ARP VCO PNP-NPN exponential pair matching

[Dave Manley]

Dave Leith wrote:
> I would like some advice on matching the ARP VCO exponential pair.
> I've searched the archives and the only advice I found was - that they
> don't need matching - either they are going to be OK and work or they
> will be so far off that you should try another pair. Any other tips or
> procedure that you would recommend?
>
> The circuit is in the standard PNP-NPN exponential pair Arp Odessey
> (ver 2 and up) ARP Axxe VCO or ARP 4027-1 VCO module (can be found on
> http://www.till.com/arptech/modmain.htm)
>
>   
The typical matching process is to pump a known current through each 
transistor at the
same temperature and measure the Vbe.

There's a Moog transistor matching circuit about halfway down this page:

http://www.diyaudio.com/forums/showthread.php?threadid=43304

-Dave