This is a control voltage splitter, inspired by a
question on the Synth DIY list. There is nothing special about this
circuit at all. It is just an ideal diode circuit.

The idea is that all control voltages greater than the break point will go out one output, and all of the voltages less than the breakpoint will go out the other. Please note that the output will always start at 0 volts. So, if you have an input voltage of 5 volts, and the break point is 4 volts (you need to apply -4 volts, the sign is inverted), the positive output (Vo2) will be 1 volt, and the negative output (Vo1) will be 0 volts. If you have a scope, put it in X-Y mode, put the X input on the input, and the Y output on one of the two outputs. Put in a triangle (or sine), and you will get a voltage transfer function, similar to the two sketches above (that is what I did).