Signal Divider plans?

[Squirrley]

I am looking for the plans to build a signal divider like the one found in the J-Pac.  It would be even better if video amp was also built in.  Can someone provide instructions for building this board or a link to a site explaining it.

_{excerpt taken from ultimarc site}

Custom microcontroller only allows sync signals to be sent to the monitor if they are in the correct range that the monitor is designed for. Avoids driving the monitor with a too-high horizontal sync rate which can damage some arcade monitors.
Sync circuitry also converts separate horizontal and vertical syncs into composite sync. Can handle both positive and negative vertical sync.
If required, can divide a 31Khz VGA signal in half so that it will display a stable picture on a 15Khz arcade monitor. Useful for checking boot-up progress and configuration (not for application use). Automatically stops dividing the signal when it detects a correct 15Khz rate is being send by the PC.

[mattv]

I realise that this is not very much help to you, but it would probably be much easier to buy a jpac.

Andy really stuck his neck out designing and selling the jpac and I'm delighted that it worked out for him (and for us). It just seems, I don't know, disrespectful, I guess that we are discussing ways to avoid ways of paying him.

When you think about what the jpac is, a custom designed, purpose built piece of electronics for a tiny niche market, with excellent support, ongoing feature releases and amazing after sales service, the asking price is, quite frankly, a bargain.

If you don't have one already I strongly suggest you buy one and then make your decision to build your own once you have tried it out. They hold their value really well and you should be able to sell it on eBay no trouble if you don't like it.

Just my opinion - for what it's worth (which is not much really)

[Squirrley]

Don't get me wrong.  I love the J-Pac idea.  My cabinet was kinda hacked together when I got it and is not really set up for Jamma.  I have no plans to set it up that way either.  I'd rather straight wire it.  The J-Pac doesn't really work into the picture because of that.  Running the ArcadeVGA and a video amp would be almost a $120 investment.  I'm trying to be as cheap as possible.  I could always go with the LPT port solution for turning on the monitor after the signal is in the safe zone but I loose all ability to see post/config.
So, as you can see, the J-Pac has the features that I need but doesn't really fit into my solution.  If they made a H-Pac, a hard wired version of the J-Pac, I would be all over it.  Until then, I'm stuck building my own equipment or shelling out $120 (not really an option).  I'm not trying to avoid paying Andy at all as I'm looking to incorporate an I-Pac for the controls.

[DaveJ-UK]

According to the quote you posted, the JPAC uses a custom chip for filtering the video signal. There are various applications where similar signal filtering will be required, so I expect there are other chips out there. You'll probably need a fist full of resitors and caps too, but if you can find a chip it can probably be done pretty easily.

The JPAC is only $60. It's a quality piece of kit as Matt says and you'll have no problem moving it on at near enough your purchase price. You can use the JPAC without an ArcadeVGA. You won't need the parellel port set up, no video amp and no keyboard interface.

Add up all the time you think it will take to build all this stuff, add a few hours (these things always take longer than you expect, don't they?), add the parts into the equasion and i'm sure you can earn more in the time and buy a JPAC.

[SirPeale]

I have to agree with the OP on this one.  For those people doing a very simple cab, using a real arcade monitor, the J-PAC is a very costly price point.  If Andy's video amp also contained the circuits for halving the signal, I'd be all over it like white on rice.

I do have two J-PACs, and they're great.  For my project, it just doesnt' make sense, price-wise.  It's a one player setup, with one button, left-right, and P1/P2 buttons (it's a Galaxian conversion).  I've hacked a keyboard to do this particular setup.

My final problem is the video.  I'd buy Andy's video amp, except it doesn't 1/2 the signal.  I'd do it in a heartbeat.  So if there was a way to get that functionality without the excess, I'd either buy it or build it.

[Grauwulf]

Has anyone spoken to Andy about this idea? Maybe if enough interest is expressed he will do the video amp/splitter combo seprate from the J-Pac. Never know unless you ask.

[AndyWarne]

This is something I have thought about doing, but no definite plans for this at the moment.

If people are interested in building a one-off board, I could supply the programmed microcontroller chip for a low price. Because the design is fully implemented in the chip firmware, the circuit is very simple, just the one chip.
The firmware is another story, that is a bit special...
BTW Thanks Mattv for your comments!
Andy

[Squirrley]

I contacted Andy a few days ago. (probably why he posted to this message)  He was very helpful and is providing me with the chip and schematic needed to build the circuit at a very reasonable price.  If anyone else is in need of a similar application, I suggest contacting Andy for help.  

Andy, great to meet you and thanks again for the help.  It's nice to see someone who'll go out of their way to help a fellow hobbiest.