Short Term Memory
Short Term Memory is a 4 channel sample and hold module with on board LFO and chaotic modulation source. Sample and hold is achieved by means of a DG412 and a fast pulse generation on the trigger input. A mode switch allows the user to switch to track and hold mode wherein the pulse generation is bypassed and the sample will not hold until the input gate returns to low. The modulation source is based on the venerable NLC Stooge with quite a few modifications including alternate feedback paths and resonant circuits. The LFO is a based on a very old and simple design that provides a nice clock and additional modulation source on board for very few components.
Short Term Memory is a 4 channel sample and hold module with on board LFO and chaotic modulation source. Sample and hold is achieved by means of a DG412 and a fast pulse generation on the trigger input. A mode switch allows the user to switch to track and hold mode wherein the pulse generation is bypassed and the sample will not hold until the input gate returns to low. The modulation source is based on the venerable NLC Stooge with quite a few modifications including alternate feedback paths and resonant circuits. The LFO is a based on a very old and simple design that provides a nice clock and additional modulation source on board for very few components.
Each sample input is normalled to the corresponding Engram output. Each gate input is normalled to the one below, aside from gate 4 which is normalled to the square wave LFO. So you could, for example trigger two channels off the LFO and two externally by patching your external gate into gate input 2.
Each sample input is normalled to the corresponding Engram output. Each gate input is normalled to the one below, aside from gate 4 which is normalled to the square wave LFO. So you could, for example trigger two channels off the LFO and two externally by patching your external gate into gate input 2.
When building, always start with the lowest and smallest components first. Resistors and capacitors, then ICs and diodes. Next install the board connecting pin headers. Install the pots, jacks, LEDs and switches with the faceplate in place to help align them. Always start with a single leg for each component, then check alignment before soldering the remaining legs. When choosing LED current resistors for the LFO, they will never see more than + or - 5 volts, so 2k2 is fine for standard brightness LEDs.
When building, always start with the lowest and smallest components first. Resistors and capacitors, then ICs and diodes. Next install the board connecting pin headers. Install the pots, jacks, LEDs and switches with the faceplate in place to help align them. Always start with a single leg for each component, then check alignment before soldering the remaining legs. When choosing LED current resistors for the LFO, they will never see more than + or - 5 volts, so 2k2 is fine for standard brightness LEDs.
You can adjust the LFO speed by changing C LFO, larger for longer LFOs or vice versa. The same is true for the chaotic modulator, which has 4 capacitors labeled C E on the board. The circuit may not oscillate if they are not the same value as each other. As long as they are the same you can make them any value from 100nF to 10uF or possibly more.
You can adjust the LFO speed by changing C LFO, larger for longer LFOs or vice versa. The same is true for the chaotic modulator, which has 4 capacitors labeled C E on the board. The circuit may not oscillate if they are not the same value as each other. As long as they are the same you can make them any value from 100nF to 10uF or possibly more.
The chaotic modulator does work well in Falstad circuit simulator, so if you plan on modifying it definitely play around with it there first.
The chaotic modulator does work well in Falstad circuit simulator, so if you plan on modifying it definitely play around with it there first.
