tpetar
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MemPot v1.0, potentiometer with a memory
Original Web address: **broken link removed**
Introduction
MemPot was developed by Dan Blackburn and me as a control interface for circuit bent instruments and sound generators. MemPot is a built around PIC 16F819 microcontroller that reads analog resistances, records them to memory and plays them back via digital potentiometer DS1267 chip. The memory buffer size and the playback speed can be adjusted.
The first PCB
MemPot was the first circuit design we finally got one proper PCB made for us. That was rewarding experience, although not without any problems. I learned myself the widely used Eagle CAD software during the design process and there are couple of things that I missed. Firstly, by mistake I chose too small resistor packages from the library, so the 6mm long, most common resistors, don’t fit horisontally but must be soldered vertically. Not a big thing luckily. The other is bit more inconvenient. I forgot to put extra solder points for GND and +5 used in the interface (outside the board) so when wiring the switches and pots, the GND and +5 must be wired to exposed points on the board. Coincidentally the exposed legs of vertically soldered resistors turned out to be just fine for this, so the first mistake kind of solved the second one.
**broken link removed**
Using it
MemPot is a controller, so you need something to control. Simple sound maker like the NandSynth or APC with resistance controlled pitch will do. If you have some circuit bent instruments with pot or LDR controlling something, hook MemPot to that. This first version of MemPot has two outputs of 100K resistances of which we are using one. You can put larger physical pot in series with the digipot output to change the range, to 500K-600K instead of 0K-100K for instance.
Power up the board and the preset buffer should play, linear ramp of 0-100K resistance in loop. Adjust the playback speed from the speed pot. Hold down the rec button and tweak the rec pot, LED starts blinking. When you release the rec button, the recorded tweaking should loop. MemPot overdubs, so when the buffer gets full, it overwrites the memory from the beginning. You can change the buffer size by entering to setup mode from the toggle switch. LED lits when in setup mode. Now you can use the speed pot to change the buffer size. Try very short by turning the pot almost all the way counter clockwise. Exit setup mode from the toggle switch, the very beginning of the previously recorded buffer should play.
Original Web address: **broken link removed**
Introduction
MemPot was developed by Dan Blackburn and me as a control interface for circuit bent instruments and sound generators. MemPot is a built around PIC 16F819 microcontroller that reads analog resistances, records them to memory and plays them back via digital potentiometer DS1267 chip. The memory buffer size and the playback speed can be adjusted.
The first PCB
MemPot was the first circuit design we finally got one proper PCB made for us. That was rewarding experience, although not without any problems. I learned myself the widely used Eagle CAD software during the design process and there are couple of things that I missed. Firstly, by mistake I chose too small resistor packages from the library, so the 6mm long, most common resistors, don’t fit horisontally but must be soldered vertically. Not a big thing luckily. The other is bit more inconvenient. I forgot to put extra solder points for GND and +5 used in the interface (outside the board) so when wiring the switches and pots, the GND and +5 must be wired to exposed points on the board. Coincidentally the exposed legs of vertically soldered resistors turned out to be just fine for this, so the first mistake kind of solved the second one.
**broken link removed**
Using it
MemPot is a controller, so you need something to control. Simple sound maker like the NandSynth or APC with resistance controlled pitch will do. If you have some circuit bent instruments with pot or LDR controlling something, hook MemPot to that. This first version of MemPot has two outputs of 100K resistances of which we are using one. You can put larger physical pot in series with the digipot output to change the range, to 500K-600K instead of 0K-100K for instance.
Power up the board and the preset buffer should play, linear ramp of 0-100K resistance in loop. Adjust the playback speed from the speed pot. Hold down the rec button and tweak the rec pot, LED starts blinking. When you release the rec button, the recorded tweaking should loop. MemPot overdubs, so when the buffer gets full, it overwrites the memory from the beginning. You can change the buffer size by entering to setup mode from the toggle switch. LED lits when in setup mode. Now you can use the speed pot to change the buffer size. Try very short by turning the pot almost all the way counter clockwise. Exit setup mode from the toggle switch, the very beginning of the previously recorded buffer should play.
