Hi everyone. I'd been trying to do a 60Hz colour fix on my MDII for ages and was getting nowhere building oscillator circuits. I had a think and came up with a different way to do it, I built a clock divider to divide the system clock by 12 to get the right frequency instead of trying to generate it, it works great and was much simpler and easier to build (worked first time). I don't think anyone has done a colour fix this way before (I didn't see one anywhere anyway). I've made a blog post about it with more details here: http://canthack.org/2014/04/a-new-mod-for-mega-drive-60hz-colour-correction/
Interesting idea. Just FYI though, here's a source of the 4.43MHz crystal oscillator - http://www.aliexpress.com/item/10PC...-21-13-21-5-08mm-Square-active/949416078.html 10 of them for ~10USD. I've modded one MD2 with one of these and it worked great - in fact the picture was obviously superior to another md2 I had modded with a 3.579MHz crystal oscillator - that one had very obvious ghosting.
Oh awesome, that's a lot cheaper than I ever found them for! If I'd known I would have gone that route, although because I don't need 10 and it only cost me a couple of pounds for the flip flops I used it actually works out cheaper for me the way I did it (considering I'd only need one or at most two of the oscillators). I guess it's also good to have alternatives anyway. I'll add a note on the blog that there is a reasonably priced source of the oscillators, thanks
You need to do a divide by 3 and feed that to a divide by 5 (or the other way around). Divide by 3 can be done with two D-types and a NOR gate, while divide by 5 can be done with three D-types, two NORs and two ORs. So you will unfortunately need 4 ICs instead of 2: 74ACT175 - Quad D-type * 2 74ACT02 - Quad NOR gate * 2 Also, I don't think you can get a 50% duty cycle, but that doesn't matter. It may be possible to do it with fewer gates/flip flops, I'm not certain.
