Wednesday, February 4, 2009

MC6847 Video Character Generator

This is the MC6847 character generator. If you look to the right side of the breadboard you can see the amps/transistors to generate the correct output signal (which I left on the breadboard for my own reference before soldering) The circuit frequency is generated with a 4 pin crystal oscillator, running at the industry standard 3.58 MHz frequency.
Below the breadboard is the soldered version of the amp/transistor signal generator. You can see the RCA jack that is plugged into a NTSC LCD monitor. That was the first time I have ever created my own soldered board, and it worked the first time! Sloppy, but it works! This circuit also works with a composite monitor -- in my case, an old Commodore 64 monitor.
This circuit will generate Black and White only, but I am planning on adding an MC1372 so color can be generated. Although I slightly modified the amp circuit by using 2N4400 amps instead of the 2N2222, the design is by Joseph Norman. Thanks Joseph!


  1. I am using your circuit to test my MC6847. It works fine. The only problem I have is the signal amplifier because I don't have 2N2222 (I just ordered them).

    Thank you for this work!

  2. You can also use the 2N4400 which is what I used.