◊ 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.

• Ring Modulator Schematic
• Original forum discussion, and continued. See bottom of this page for errata.
• FPD front panel file (New!)

PCBs are $15.00 @ — ORDER HERE

Bill of Materials (value/qty)

• Resistors
  • 10k x4
  • 100k x2
  • 1k5 x4
  • 220r x2
  • 2k2 x1
  • 22k x1
  • 330r x2
  • 3k3 x5
  • 33k x1
  • 47r x3
  • 680r x6
  • 6k8 x4
  • 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 (or substitute 2.2r 1/2 watt resistor)

*Errata/Notes

[updated 02/23/2025]

• 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.
• R14 and R19 on our PCB are incorrectly marked as 10r; they should both be instead be 10k. Thanks to Dave Brown for pointing out this error. (see image below)
• Dave also recommends the following resistor value changes to improve levels:
• R14 and R19 from 10k to 1.5k
• R9 and R11 from 3.3k to 1.5k