NLC 7555 VCO

• 4 hp, Black Panel
• Fresh build, tested, calibrated, and fully functional
• Reverse power protection installed, comes with power cable
• Built with highest quality WQP-518MA jacks (20k+cycles)

Further information from Nonlinear Circuits:

Not the most exciting name, I simply wanted a 4HP sawtooth VCO to sit next to the Spectrum Shaper.

It is based on the Utility VCO in Electronotes EN67, which was based on designs by R. Tenny (Electronic Design 11/10/75), J.L. Brice (Wireless World (6/76) and others.

It tracks very nicely, turn the CV pot to max for 1V/oct, ranges from approx 10Hz to over 100kHz and supplies 10Vp-p sawtooth and square waves.

The Sync is the hardest of hard syncs around. I left out the capacitor usually used to turn sync signals into a pulse, so if you feed a gate or slow CV signal into Sync the VCO simply stops, think of it is a bonus VCA. Of course, if you use an audio rate sync signal, it works as normal.

It is a pretty easy build. not many parts. Do not mix up the BCM847 and BCM857 dual transistors, see the build notes for where to install a 1k tempco.