This must be one of the simplest video pattern generators one can realize. It provides a black/white bar pattern. The circuit is designed around a 1$ 4060. This is a 14 bit counter.
A steps shaped block wave is created by adding the 3 output signals (contacts 4, 5 and 7) in the proper proportions.
The output signal can be adjusted to the required 1 Volt peak-peak. Contact 4 (Q5) provides a f:64 signal. When the Xtal is choosen as 1 MHz, output Q5 delivers a 15,625 Hz signal. This is what is required for the 64 us synchronization pulse (0 V).
I did trials with various Xtal frequencies and 4.43.. MHz provide three main bars each consisting of 8 subbars. I presented this signal to a small QRP ATV 1.2 GHz transmitter and when received by an analogue satellite tuner, the picture above was seen on my TV.
The circuit was realized according to the " dead-bug " rules:
If you know how a simpler video generator can be made than presented here, I am very interested.
Typical PAL video signal providing a bar pattern:
Hello, is it possible to upload a schematic for this design? I can't see the attached picture very well.
ReplyDeleteYou can use multiples of 4 MHz as a crystal frequency (2, 8 or 16 MHz)
ReplyDeleteby selecting the appropriate outputs from the 4060 for summation.