The ELM304 is a B&W test generator for DIY-ers. It comes as an 8 pin DIP and operates from +5. (It will also operate from a 3v coin cell with some component changes.) For 9V operation you will need to add a 5V regulator (78L05). It uses a 3.58 MHz crystal to generate full sync and a 4 level stairstep signal.
https://www.elmelectronics.com/wp-co...7/ELM304DS.pdf
The completed circuit is small enough to mount in a minibox. Great for use in the field when evaluating RSF's (roadside finds). It works with anything with a composite input.
The ELM304 comes to us from the same people who produced the ELM327, the very popular OBD2 automotive interface.
https://www.elmelectronics.com/
I have been told ELM is closing for good June 2022.