Recent PCB Projects

1. Custom Bitcrusher Guitar Pedal (breadboarding in progress)

Major Design Decisions + Features:

• The pedal will be a mixed signal, 4 layer board. Board is being designed in KiCad.

• 12V and 5V power rails

• Hybrid pedal with 2 modes: (1) analog mode where bitcrushing is handled by analog switching and (2) digital mode where bitcrushing logic is handled by an arduino nano. User can select which mode by flipping a switch that controls a MUX. (I made the pedal have two modes as a learning exercise to get better at designing mixed signal boards.)

• Signal path: The input audio signal is first routed into an 8-bit ADC, which is clocked by an LTC1799 oscillator (this sets the sample rate). After conversion, the ADC’s 8 output bits go into a bit-masking stage built from logic gates. Each ADC bit is routed to input A of an AND gate. The other AND input (input B) is a control bit mask that determines whether that ADC bit is passed through or forced low (bit crushed). This control bit mask can come from two selectable control paths:

  • In analog mode, the user sets the bit mask manually with an 8 pin DIP switch. The DIP switch outputs go into a 2:1 MUX, which passes the selected mask bits to the AND gates. The AND gate outputs (the masked 8-bit word) are then sent to the R-2R DAC, followed by an LPF and output level potentiometer for smoothing and volume control.

  • In digital mode, the user sets bit crushing intensity with a potentiometer connected to an Arduino Nano. The nano generates the corresponding 8 bit control mask and sends it to the other input of the 2:1 MUX. The MUX selects this MCU generated mask, which is then applied to the ADC bits by the AND gates before the signal goes to the same DAC + LPF + output stage.

• Bitcrushing firmware will be uploaded on my github here. 

2. Analog Video Processor Version 2 

Major Design Decisions + Features, Improvements from V1:

• Designed a 4-layer analog video processor PCB in KiCad with 75 Ω impedance-matched composite I/O (top and bottom signal layers, solid inner ground plane, dedicated power plane)

• Expanded the power section to generate +/- 12 V and +/-5 V rails

• Designed custom footprints for a few components

• Used a hierarchical schematic: a parent sheet for power, I/O, and switching, and three subsheets for each individual glitch circuit

• Implemented 3 video glitch circuits in parallel:

  • A video enhancer stage (from V1) that boosts/attenuates the video signal and effectively lets me push saturation/contrast into overdriven, glitchy territory.

  • A custom “luma trap” notch filter, designed and simulated in LTspice, that removes a narrow band of the luminance/chroma spectrum to produce color shifts.

  • A comparator/video mixer built around an LM393: the incoming video is compared to an adjustable reference (coarse/fine threshold pots), its edges converted into a pulse train, divided down with a binary divider, then two selectable divided outputs are attenuated and mixed back with the original signal for harsh, pixelated looking artifacts.

• The board is currently being soldered w/ the goal of integrating gesture controls and using it as a modular analog video glitch platform for live music performances.

3. Analog Video Processor Version 1 (demo video below)

Major Design Decisions + Features:

• Designed a 2 layer analog video enhancer PCB in KiCad, inspired by the Archer video enhancer circuit

• Processes composite video to adjust image saturation/contrast in real time to produce cool visual effects

• Implemented 75 Ω impedance matching on the video I/O to interface cleanly with typical composite video gear

• Used a solid ground plane on the bottom layer to reduce noise and keep return paths short for the analog video signals

• Routed power and all signal traces on top layer, keeping the layout easy to debug 

• Board was assembled with spare electronic components from a local makerspace to stay within $50 budget