cut a standard TRRS cable and change pins for the video Signal to get TRSR (left/right/ground/video)
enable raspi composite video out (bookworm)
change /boot/firmware/config.txt (by default NTSC – to change this see documentation)
dtoverlay=vc4-kms-v3d,composite
enable_tvout=1unplug the HDMI cable and reboot the pi
https://www.raspberrypi.com/documentation/computers/config_txt.html#composite-video-mode
test: when signal is on composite monitor type the following in ssh
DISPLAY=:0.0 firefox --kiosk http://ontime-server.local:4001/timer
this will show you the ontime timer. or simply write zimt.atenable raspi composite video out (jessie, wheezy, buster,…)
change /boot/config.txt:
# use for sd-out
sdtv_mode=0
hdmi_ignore_hotplug=1
sdtv_aspect=1 # for 4:3
#sdtv_aspect=2 # for 14:9
#sdtv_aspect=3 # for 16:9
dtparam=audio=on
start_x=0