Mosha Eurorack modules #1: Triple LFO

The triple LFO is a 6 HP module that, as the name implies, as three LFO. 

• The silver LFO has a -5V to 5V triangle output, a -5V to 5V square wave output and a 0V to 5V square wave output and has a medium speed (~2s to 0.2s).
• The purple LFO only has a -5V to 5V triangle output and a slow speed (~20s to 2s).
• The golden LFO has a -5V to 5V triangle output that can be attenuated with the second knob, and a 0V to 5V triangle output. Each of the LFO has an LED indicator that switches between red and green.

The design is based on the Simple LFO design from David Haillant. Modifications include having three different capacitor values, the replacement of the lower bound resistor with a 1.5k instead of a 470 Ohm resistor and having a fixed output path. What wasn't fixed is the missing 1k Ohm resistor at the output, so shorting the LFO can cause it to reset. For the 0V to 5V square wave a diode was added and a pulldown resistor.

For the 0V to 5V triangle wave the circuit below was added, which basically is an inverting amplifier that adds approximately -5V to the output of the LFO. This causes the LFO to fluctuate between -10V and 0V. The amplifier divides this by 2 and inverts it, resulting in 0V to 5V. Although the circuit mentions the TL081 the entire LFO was built using TL074.