Quote:
Originally Posted by NoPegs
Possibly more accurate to get a 31.5khz crystal and use a PLL to scale it x10. The 555 has way too much drift to be used in this kind of application.  |
Certainly not as good as a crystal, but: to use the color bar function (as opposed to using the generator for a sweep frequency reference) this app needs +/- 1% max tolerance - it's only affecting the H and V frequencies, not the color. The 555 chip itself has a freq tempco of about 90 ppm per deg C. , so I think it would be feasible with a polystyrene cap and small trimpot. Even if it did drift a little too much, you could just turn the pot until the TV set syncs.
Not saying it's elegant, just a way to run without a crystal.