[sdiy] 3046 vco help?

[KA4HJH]

>  Terry - I'd be very interested in seeing that conversation if you
>could dig it out without too much trouble for yourself.... I've got
>some 1K tempcos (only 3000ppm though) lying around, and a few VCO3D
>boards...

I couldn't find the thread about the design of it. I think that was on this
list before Tom started his own. I did find these instructions:

At 1:01 PM -0700 10/16/01, tomg wrote:
>There are only 2 tempcos...
>
>To use the heater operation....
>Ignore the resistor labeled "TC-R" and use 1K resistors for "TC" 1&2.
>
>For tempco operation....
>0) Use tempcos for "TC" 1&2.
>1) Replace R44 (33ohm) with a 10K and use a 1K for "TC-R". This
>    forms a voltage divider that puts about -1V on U1 pin 13.
>2) There is a extra pad connecting U1 pin 14 to +V break the trace here
>    and remove R43. The 12,13,14 transistor in U1 is now disconnected
>    B-n/c  C-n/c and E to -1V
>3) Remove R40,41,42 and T7. Put a jumper in place of C8.
>4) Remove the jumper from U5 pin-3 to U1 pin-6.
>5) Connect the pad from U5 pin-3 to ground. This removes the heater
>    drive and disables opamp-A in U5.
>
>Note that the 2 opamps in U5 are numbered wrong on the schematic.
>The referance opamp (b) should be the 7,6,5 opamp and the heater drive
>should be the 1,2,3 opamp (a).
>
>Tom

Ten years ago. How the time flies...

-- 

Terry Bowman, KA4HJH
"The Mac Doctor"