Synthesizer - Clock module
This is a Eurorack synth module which combines a collection of common tools for transforming signals, either control voltages or audio signals. While there are several distinct utilities, most are not mutually-exclusive.
This was the first module I designed.
- Correct some noise
- Design a Revision-B PCB
- Assemble PCB
- Cut and decal panel
A_IN is disconnected,
OUT is a constant voltage output based on the position of the knob.
OUT is 0V when the knob is in the center position, and adjusts up to +/- 10V.
Buffer / Scaler
A_IN is supplied, it’s value is buffered to
OUT. The knob position linearly adjusts the output gain. At the center position,
OUT is the same as
A_IN. At the full-left position,
OUT is off. At the full-right position, the value of
A_IN is doubled.
B_IN is supplied, it’s value is added to
A_IN before applying scaling.
~OUT is always the inverse of
GATE is supplied with a digital voltage, it allows disabling
~OUT) at logic-low (0V). An LED indicates when the gate is open. When
GATE is not supplied, the outputs are always enabled, and the LED remains off.
OR can be implemented by summing signals on
B_IN With the knob at the 1/4 position. Digital
AND can be implemented by applying one signal to
A_IN and one to
GATE with the knob at the 1/2 position.
A summing inverting amplifier with a variable feedback resistor handles the adder, inverter, and scalar. A connection on either A or B toggles an analog switch selecting between a constant voltage source and the summing output. Another analog switch controlled by the gate allows that signal to be toggled before it is buffered in both an inverted and re-inverted back to positive outputs.
This manages to use an extreme minimum number of parts, requiring only one quad op-amp and one dual analog switch. Some switching and transistor trickery is used to configure the behavior depending on what patches are connected.