RotaryCell / build guide

Prepare the cables

This page records the cable lengths, colors and pin assignments used in the working build. It assumes you already know how to strip wire and crimp the contacts correctly.

Wire colors are not part of the circuit

You do not need to copy my wire colors or follow the same overall color scheme. I used a combination of what I had available and what helped me keep the wiring straight. Use colors that let you distinguish conductors wherever polarity, connector orientation or signal identity matters, and record any substitutions you make.

Audio board to carrier

Use a 10 cm three-conductor cable between Audio A4 J2 and carrier U2. It is wired straight through, with blue outer conductors and black in the center.

Audio A4 J2	Carrier U2	Signal
Pin 1	Pin 1	VIN
Pin 2	Pin 2	GND
Pin 3	Pin 3	VOUT

Completed three-conductor audio-board-to-carrier cable

Carrier to telephone network

The two-position NETWORK connector on the carrier runs to the telephone's network block. Use green for tip and red for ring so the original telephone convention remains obvious during installation. Leave the network block ends untrimmed until the boards are in the phone.

Audio interconnect and red-and-green network cable

Remaining harnesses

I use this crimp tool and connector kit for the harnesses. The kit also supplies the through-hole headers for the boards.

The four charging, battery, AG1171 power and AG1171 signal harnesses use 10 cm conductors. Current-carrying red, yellow and black conductors are 24 AWG, while signal-only conductors are 28 AWG. The three-wire hardware-reset harness uses 16 cm red and yellow 24 AWG conductors and an 18 cm green 28 AWG trigger wire. The LilyGO audio harness uses 28 AWG wire: 14 cm black common, 18 cm blue tone, and 10 cm red SPEK+ and MIC+ leads. Both two-position audio cables begin at 10 cm; remove the black SPEK- conductor and trim the black MIC- conductor during final soldering.

Check the finished cable

Verify every conductor end-to-end and check for unintended connections between adjacent pins. Gently check that each contact is retained by its housing.

Connector names repeat

Audio A4 U2 is the reset connector. Carrier U2 is the audio connector. Always include the board name when checking a connection.