[sdiy] ARP VCO drift - update

[rob]

Hi list,
Quick update on progress.....I fitted a BC847BPN dual NPN/PNP transistor to
the Tempco using heat paste and wrapped the 2 together using insulation
tape, even though this is remote from the main PCB. The BC847 was fun to
wire up....its super glued to a tiny piece of veroboard with thin wires to
the SMD transistor and larger wires to the PCB.

VCO frequency drift has now reduced to a similar level as a Dual
SSM2210/Tempco based VCO (Oakley or E-mu Systems). I test with a frequency
counter, but the real test is to listen to the 2 VCO's at the same pitch and
hear the tones beating. They are now nicely beating against each other with
a 5 - 10 second phase rather than quickly going away in pitch.

The transistors and tempco will now be put on the main PCB and I'll carry
out the next set of tests. 1v/octave Tracking....maybe I'll pot the whole
circuit....

Thanks - Rob
www.emulatorarchive.com