This pdf contains a wiring diagram to show how to interconnect the eTap2hw motherboard, Piet’s Universal Interface shield and the pots and input and output jack sockets to complete the basic wiring of an automated echoTapper unit using Piet’s original FET-based preamp design. The wiring of the valve preamp unit will be covered at a later date.
It is assumed that you will connect the Arduino Uno, the Universal shield and the Adafruit LCD shield by stacking them one on top of the other (in that order) using ‘stackable’ headers, with the whole ‘stack’ mounted on the front panel via suitable M2.5 bolts and nuts. This earlier post shows what I mean.
It is also possible to mount the LCD separately on the front panel and connect it via four wires to the Universal shield’s I2C connector (top left in the photo above). The Uno and Universal shield would then be mounted perhaps in the base of your unit.
This would be absolutely necessary if you are mounting the unit in a 1U 19″ rack mount as the Adafruit LCD will not fit as it’s too deep. Piet should soon have available a special LCD/Buttons kit that is specifically designed to fit a 1U rack panel which will also connect via the I2C connector.