Hi all,
for experimenting with discrete amplifier circuits I'd like to have a source for maybe two (4?) variable voltages, say +-10V. Simple solution would be 10-turn potentiometers. But of course much nicer would be a device with display, encoder...
Calibrators do that, but are much too expensive for this purpose. A simple device with microcontroller and 2-4 channel DAC would be sufficient. Is anyone aware of a project like this?
If I would do it, I'd simply use off-the-shelf components (reference, DAC, OPs) from the (not too) top end (let's say <$50 total) and see how far this would get me (without any LTZ1000 style fiddling). Maybe 20 bit DAC (4xDAC1220? OK make it $100), best $10 reference and so on. But still this is a lot of work, from power supply (make low noise +-15 V from what battery), microcontroller, display, USB, calibration EEPROM, analog part... all limited if possible to JLCPCB assembly parts (did enough manual SMT assembly for a lifetime). This would be a great apprentice project...
So if anyone is aware of an existing solution/project that can be bought/built with reasonable effort/cost, I'm interested. A quick search on Aliexpress turned up nothing, maybe not something the maker crowd would need.
EDIT: It seems there is a handful of DAC1220 boards on Ali. No display though.
EDIT2: Couldn't resist doing a quick search what I would use:
Power supply: 9V alkaline battery, 3.3 V and 5 V LDO, extra filtering for 5V analog (maybe 5.1 V for DAC1220)
Traco TEC2-1223WI DC/DC module from 9V to +-15, heavy filtering (L-C-L-C-L-C with large ferrite beads) for reasonably clean +-15V (maybe extra high PSRR LDO to +-13-14 V)
Analog: MAX6126 2.5 V reference, 4xDAC1220, OPA182 for 0-5 to +-10V conversion and output buffering
Digital (mostly this would be copy+paste from a recent project): STM32G0, 24C02 EEPROM, EA DOGXL160 display (without backlight - needs to much power), Encoder, Keypad
Maybe throw in USB interface... (I think this is called feature creep)
Thanks, Martin