presenting the amb/linuxworks alpha 10 audio preamp:
some inside shots:
earlier prototype in smaller box and in passive-mode (not using an active line-stage buffer):
the heart of the system is what we call the LCDuino. its at version one so its the LCDuino-1. project page for it:
I've been working with AMB labs on this project for well over a year, now. we have a backpack LCD/IR/motor pot module (LCDuino), a relay R/2R volume control (stepped attenuator) called the Delta1 and an 8port i/o selector called the Delta2. recently we created a motherboard for this to hold a 5v reg board, a dual 12v analog reg board, 2 JISBOS unity gain discrete analog line drivers and the stack of D1/D2 boards and their controllers.
there's even a basic online web GUI to calculate the R values for the resistor/relay stepper:
older shot of a few relay attenuator boards and their controller halves:
CAD image of the top and bottom of the LCDuino:
the board has molex header support for:
- analog 'resistor' buttons
- RTC via ds1302 and supercap backup
- LCD display via mcp23008 PE
- IR input via vishay IR module (learning)
- IR out via IR blaster
- motor-pot via h-bridge l293d
- i2c used for relay and inter-module comms
- config button for programming
- amplifier switched ('blue wire') out for remote power
I'm finishing up the firmware now (last count was 15k lines of C code) and will post links when its ready for testing. I've been using this as my main home stereo controller and preamp during the last year or so and its been great fun replacing my yamaha and other commercial gear with all DIY stuff.
my partner (AMB.org) will have bare pc boards on his website when the software is ready to be released. we plan to sell circuit boards and possibly kits.