superg wrote:
Yeah, I know this. According to standard I shouldn't drain power from pin 8 but it's very convenient not to have external power supply and there aren't a lot of official cables now. Next version will have integrated DC jack on PCB (now it's floating cable which goes to board through SCART connector, not very handy but at least some compatibility). Another nice use-case with power over pin 8 is daisy chaining with only one external power supply. So simply it supports external power only on first switch link in daisy chain, and not relying on pin 8 or power from pin 8 from unofficial cables and IMO it's best compromise, user will decide what's best for him.
Also I would like to mention, that switch is almost transparent in terms of power consumption. If not lm1881 (which consumes up to 10mA), it consumes around 1mA. But I agree that having lm1881 on board is a good idea.
Fair enough. However, this brings up another point. As I read that I thought to myself it's impossible - how can anybody drive four video lines with only 1mA? Then I read some posts on your other thread an realised how it works.
What you have built here is an automatic passive video switcher. The is not how video switch boxes are normally made. The conventional way is to terminate the video (at 75 ohms), use a CMOS multiplexer to switch between channels with a buffer amplifier on the output with 2x gain to drive the output. The on resistance of the multiplexer not very important now so you can use cheap switches like the SN74LV4053. But that's not the biggest advantage of this method.
The problem with the passive switch is that parasitic properties of the video cables get worse with the length. The quality of SCART cables is generally not good, but it's generally not a big problem if the cable lengths are kept below 2 metres. If you plug a game consoles into two passive SCART switches daisy chained from a with 1.5m long SCART interconnects you will have a 5m long transmission line of poorly defined impedance.
superg wrote:
viletim wrote:
-For production volumes you can buy connectors directly from the connector factory. The prices are much lower than distributors and they can make them in any colour you like.
It's definitely nice suggestion, however I still need to figure out a demand for such a switch. I have no idea how many units I will be able to sell at all, and it's a bit risky to invest bigger amount of money for SCART sockets without knowing whether I will sell them all.
Oh yes, of course. I just meant to point out that the price of consumer electronics connectors may be lower than you expect. For example, you could buy 1000 pcs of good quality Taiwan made SCART connectors for US$210 from 4uconnector.com according to the currently listed prices. This way you can get the specific kind of connector you want (including colour!), rather than whatever the distributor feels like stocking.
superg wrote:
viletim wrote:
-It's a good idea to have both the mini-DIN8 and SCART connectors for output. Making special cables is no fun.
Yeah, but with MiniDIN I still need to solder the other end myself (being it SCART or another MiniDIN). I think I will use same straight SCART for output and by default I will provide SCART->SCART cable (which is standard, I will just need to find inexpensive source of them)
And as an option I will offer SCART->MiniDIN. BTW: where can I buy MiniDIN cable assembly like the one you're using in your NESRGB kit?
(digikey has this one:
http://www.digikey.com/product-detail/e ... ND/2625275, but I think it's too thick and expensive also)
When I last looked I didn't find anything suitable from my usual wholesalers. The 8 pin mini DIN cables that I did find were old Apple Mac printer cables that have some wires crossed over. The cables I sell in my shop are made for me by a small cable factory in China.