◊ PCB Documentation

111 Ring Modulator

All-discrete ring mod based on the one half of the Buchla 111 circuit. Note: original 111 was a dual; this PCB is for a single ring modulator, so you would need two for a clone project. Adapted from PCB design by vtl5c3.

PCBs are $15.00 @ — ORDER HERE

Bill of Materials (value/qty)

  • Resistors
    • 10r x2 *
    • 10k x2
    • 100k x2
    • 1k5 x4
    • 220r x2
    • 2k2 x1
    • 22k x1
    • 330r x2
    • 3k3 x5
    • 33k x1
    • 47r x3
    • 680r x6 x5
    • 6k8 x4
    • 680k x1 *
    • RA 22k x2 (optional input attenuators)
    • RB 1k x2 (optional input attenuators)
  • Capacitors
    • 2n2 x2
    • 0.1uf x1
    • 4.7uf x2
    • 5.6uf x2 *
    • 10uf x1
  • Transistors
    • 2n3904 x7
    • 2n3906 x3
  • Misc.
    • .100" 4-pin power header x1
    • ferrite bead x1


  • On the schematic, R38 (47Ω) is shown tied from Q8 to several of the other transistors; it should instead be tied from Q8 to V+. This correction is made on our PCB.
  • The polarized 5.6uf caps by the outputs are shown as 56uf on the schematic; 5.6uf is believed to be correct.
  • Based on examination of an actual unit, Apetechnology reports that R27 (given as 680Ω on the schematic) should instead be 680k. (see image below)
  • R14 on our PCB is incorrectly marked as 10r; it should instead be 10k. Thanks to Mike Peake for pointing out this error. (see image below)

Marked 680Ω on PCB, substitute 680k

Marked 10Ω on PCB, substitute 10k