◊ PCB Documentation

144 Dual Square Wave Oscillator

Two independent oscillators in one unit. Frequencies are continuously variable from 5 cps to 20 kc and may be controlled internally or with externally applied voltages. There is provision for wide band amplitude and frequency modulation.

PCBs are $25.00 @ — ORDER HERE

Bill of Materials (value/qty)

  • Resistors
    • 10R x 2
    • 1K x 2
    • 10K x 18
    • 1K5 x 4
    • 15K x 4
    • 2R2 1/2 watt x 2
    • 220R x 2
    • 2K2 x 12
    • 22K x 6
    • 220K x 2
    • 330K x 2
    • 3K6 x 4
    • 470R x 2
    • 4K7 x 6
    • 47K x 4
    • 68K x 4
    • 900R x 2 (or 910R)
    • 1K trimmers x 8
    • A50k audio taper potentiometers x 4
    • B10k linear taper potentiometers x 2
  • Capacitors
    • 47pf x 2
    • 100pf x 4
    • 910pf x 6 (can sub .001uf)
    • .001uf x 2
    • .0022 x 2 (polystyrene)
    • 1uf x 2 (tantalum)
    • 15uf x 4 (tantalum)
    • 56uf x 2 (tantalum; can sub 47uf)
  • Semiconductors
    • 1n457 x 10
    • 2n5550 x 4
    • 2n4916 x 4
    • 2n3391 x 2
    • 2N5020 2N5460
    • 2n3565 x 6
    • J201 x 2
  • Misc.
    • .156" 4-pin power header x1


  • Note: In the original schematic, there is an error in the expo-converter section, first identified by the inimitable Don Tillman (nice circuit analysis there, too). 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.
  • Transistor substitutions:
    • Q1/Q2, NPN matched pair: IT-122 is unobtainium - substitute 2n5550 (a matched pair of 2n3904 may also be used)
    • Q3/Q5, 2N4916 PNP: technically obsolute but pretty easily available NOS; 2N5401 would be a recommended replacement (check pin-out)
    • Q4, 2N3391 NPN: currently available from Mouser
    • Q6, P-channel FET: U47 is unobtanium, substitute 2N5020 2N5460 (thanks Mike Peake for the updated recommendation)
    • Q7-Q12, 2N3565 NPN: currently available from Mouser as PN3565
    • Q15, N-channel JFET: E101 is unobtanium, substitute J201
  • Some builders have substituted 2n3904 for all NPN and 2n3906 for all PNP transistors, across the board; I've not tried this yet myself.


    The text, images, graphics, and other content of this website related to Don Buchla's legacy synthesizer designs is made available under the Fair Use Doctrine of the US Copyright Office. Fair Use limits the use of this information to personal, educational, and scholarly purposes (including right-to-repair, where applicable). It may not be used as the basis of commercial or for-profit works. Our Printed Circuit Boards may be purchased and assembled for your personal or educational use, but may not be manufactured and sold as "Buchla" products.