Robot Dialogs

Here's another LFO module, this time in only 7 HP. Like the previous post about an LFO , the chip at the heart of this one comes from Electric Druid's line of LFO chips. This one is the STOMPLFO chip. The design started on the breadboard as usual. I ruined one chip by putting a 5V regulator backwards. With the testing on the breadboard I gained a better understanding of how this chip works, the most interesting thing was the PDM output rather than PWM like the VCLFO10 in the previous design. I hadn't come across using PDM before.  In this scope image it's possible to see the PDM and the resulting wave (after amplification to 10V). The output stage just has a filter (passive filter from the data sheet) to tame that PDM signal. Much easier to implement that the PWM filter for the VCLFO10. I like my CVs 0-10V so I've amplified the output of the chip and that meant another op-amp was free to have an inverted signal too, so that's the outputs.  As for inputs, there...

Here's a module that's a completely overkill VC LFO.  It's based around the Electric Druid VCLFO 10 . I picked up three of these (component shortages). This design is pretty much a full breakout of all the functions the chip provides. I laid out the design first on the breadboard. Note, there's a second LFO on the right side, and a VCO on the left side, more on them in other posts. I reused a few things between the two LFOs and didn't want to breadboard that stuff again. Outputs The chip offers 16 waveforms in two sets. To use them the circuit needs a way to select those waves, I've used an 8 position rotary switch. To switch between the wave sets there's another toggle switch.  I'm using the filter shown in the data sheet to convert the PWM from the chip into the desired wave. I wanted to try an LED circuit driven by an op-amp that is similar to the circuit in the Befaco Dual Attenuverter . That meant an extra op-amp on board so I used another op-amp fr...