First some background information. Some time ago I was searching for good quality SCART switch for my retro console home setup. Here are my requirements: a) support up to 16 connected consoles (as of now 10 RGB and 3DO is waiting to be RGB-modded. Plan to get NEO GEO's and SuperGrafx/CD2 in future, those are expensive!) b) good picture quality c) 5+ input SCART connectors per switch d) I am lazy, and I like to have everything as automatic as possible, no buttons, no remotes, etc. SCART connector was a common way to connect your console to TV in my Eastern Europe childhood , so I didn't expected any difficulties with that. My initial idea was to buy 2-3 switches and connect them simultaneously using daisy chain. Typical scenario is "came from work tired, turn on random console and play some games, no cable switching, etc.". However what I was able to find were: 1. Hama 100S (and clones) 4x manual switch ~$25 per switch, I would need like 4+ of them, which is >= $100, and it will be a hell to switch all of them manually; 2. Two used Keene Commanders with ridiculous $350 price for both ($200 for one with box, $150 for one without); 3. NoName shitty 5x "switch", which doesn't have any logic inside, all 21 pins interconnected in parralel and because of this, when you turn on one of your consoles, some of others will be powered also, it's depending on circuit . Still ~$15 for one. I was heavily googling, and found out, that all European manufacturers discontinued those switches, because now everybody is using Component/HDMI, and SCART is deprecated. That said, I came with an idea to develop my own SCART switch box with focus on video quality and proper circuit design. This started ~3 months ago, and today I have final PCB design, and a batch of SCART connectors, which I managed to get very cheap (nice sturdy plastic, $0.3 per piece). PCB was designed by my father, who is long-time professional engineer, I did what I could (designed SCART footprints, specifications, features, components, etc.). So here are features: 1. 8 Euro-SCART input ports; 2. full RGB and stereo audio channels separation; 3. full automatic switching; 4. "keep it simple stupid" design, no microcontrollers, no firmwares, no FPGA; 5. low power consumption; 6. powered from SCART connector (no external power supply); 7. integrated LM1881 sync stripper (which can be turned off anytime with switch); 8. Mini-DIN output connector for XRGB-Mini owners. As of now, I am performing some final PCB checks, calculating components/labor/pcb price, and starting from next week I will be ready for PCB manufacturing. I would like to have your opinion on such a device, whether any of you will be interested to get one. I am not planning to make a fortune on this, it started as hobby project, so basically I would like to cover my expenses with first batch. Any extra I will get will be used for my next projects . Also I have two questions for you guys: 1. Where in USA I can manufacture PCB's cheap? I can do that in my home country Ukraine, that's known market to me, however I am in USA now, so I am considering to print boards here. 2. I need some case for this switch. Initially I was planning to use two plexiglass laser-cut panels (like beharius's Hanzo) with set of screws. I need some cheap place to cut these for me, and also maybe you have other ideas regarding case material/shape/process. Should be cheap . UPDATE: First run: Proto:
Curse you, stealin' my thunder! For your PCBs, have a look at ITead studio. They're based in China, but have a reasonably good turnaround, and damn cheap. USA-based PCB makers are going to charge a premium, just because of the cost of doing business. You could try somewhere like OSH Park, who are USA based, but they charge linearly with PCB surface area, so big monolithic PCBs are expensive, but numerous small PCBs are quite cheap. What are you using to isolate the inputs not currently selected?
very nice, I will have to keep this is mind for my setup also nice to see another person in Michigan! for places to get PCB's made here in the states I was reading about http://www.seeedstudio.com never used them just read that people have got stuff done by them recently.
I'm not sure about them. A member here and on YouTube by the name "Game TechUS" used them to have some boards made for a video plug on his NES RGB mods and he had nothing but hell with them. Maybe it was just bad luck. I don't know. I just know after his many videos about them and other news updates on the RGB NES stuff that I feel wary of them.
I thought he said in his video that his design had problems, and they he was gonna have to make changes. He had 20 parts made (4 parts per board, 5 boards total) for like $18 even from a prototype to test would be worth to me for testing out. But yes there was some issues. his video on them is here https://www.youtube.com/watch?v=syuzXGp-BZ4
I've seen the videos. I'm not talking about that at all. What I'm getting at is the lack of communication and the fact the ones he did finally get to speak with seemed dumb as rocks. He did say those things in another video or that one. Don't remember which...
I understand that, I was just putting the video here so that someone that who wanted to know what we was talking about could basically see that for themselves
Do you plan on doing this as a personal project ? its probably to early to ask but are you considering making a limited run or a kit of somekind ?
Multiplexer Switches: For audio I am using Analog Devices ADG608, for RGBS - ADG708. For switching TI HC148 priority encoder is used.
It looks interesting, but I really don't like the automatic switching. I like to be able to manually switch between inputs - it comes in handy sometimes. Also, some SCART cables don't have the switching lead, so I imagine those cables wouldn't work properly.
I plan to order 10-50 PCB's with first batch, order amount highly depends on price. I have no idea on demand, and obviously I would like to test few first, but switch schematic is simple enough, so there shouldn't be any problems with that. I think, 99% of people would prefer fully finished device with some sort of case, so that's like a target. For geeks who will be able to do everything themselves, I can send just board for manufacture price . Thanks guys for all replies! I will definitely contact several manufacturers for quotes, once I will finish my preparations.
Initial plan was to have Altera FPGA on-board with one toggle button. That could support automatic and manual toggle switching using different firmwares. But when you use FPGA, you have to put JTAG header, flash firmwares, debug. And also Altera eats much more power. Too much complexity for such a simple device, so this idea was scraped. As of different SCART cables, well, I have number of RGB consoles here, and also I checked RGB-SCART diagrams for consoles I don't own, and power pin is always there at console side. If somehow it wasn't routed to SCART, it can be fixed. And if not, proper cables aren't that expensive. What I mean here is that it's much more convenient not to support faulty SCART cables and have simple and proven switch design, than to try to support everything. Also solution with Altera would be more expensive.
Cool, I thought that would be the case. I'm using ADG715, similar deal but I2C controlled. Here's something you should keep in mind for your audio switching: The switching elements in those ADG*** multiplexers are plain old N-channel MOSFETs. MOSFETs don't block current flowing from the drain to the source, so if you have an AC coupled signal such as audio hitting a closed gate, this happens: This was captured with the gate closed. The blue trace is the signal on the source, and the yellow trace is the signal on the drain. The solution to this is to bias up the audio by a volt or two before the signal enters the multiplexer, then put a capacitor in the output to remove the bias before entering your TV or amp. Edit: On closer inspection, the ADG608, which you did choose for audio, has an analog signal range of Vss to Vdd. Unless you have a negative voltage rail, though, Vss would be connected to ground, effectively making your range 0 - Vdd. The notes say "In the OFF condition, signal levels up to the supplies are blocked." Edit2: Sorry. I don't mean to preach, or tell you how to suck eggs, I just wanted to share the lesson I learned after my first design exhibits "crackling" if audio comes through an input that's "off". Maybe you already thought of this! :-S
It's definitely helpful as I am not an expert in electronic circuit, I know only basic stuff, I will re-check everything tomorrow, thanks .
Those SCART sockets look really cheap and nasty. You want to go for quality connectors, not ones that don't cost you much. And that's the reason I don't like switchers, especially automatic ones - signal quality suffers. It's not for me, but good luck with the project. And yes, American PCB manufacturers will be expensive.
I want to go with some de-facto standard. I thought about using MiniDIN for inputs as well, but nobody sells these cables for consoles, and I doubt anybody would want to replace scart on their cable to minidin. BNC is not an option also. Usually people use RGB-SCART cables. And these particular scart sockets I managed to got - they are very high-quality comparing to what I've seen.
