Part="LM2904"> Dual Operational Amplifiers, DIP-8/SOIC-8/TSSOP-8/VSSOP-8Standard switching diode, DO-35Standard switching diode, DO-35 | | | | Tayda | A-3588 | \** Use only four (4) potentiometers, either 9 mm or 16 mm have been tested and there could be mechanical difficulties using 9 mm. See [build.