I've just read all of this jibberish about building a circuit for the EL1881 sync-separator, and by God, I am having a really hard time understanding it. Here's a link to the data sheet for the chip, someone please help me translate some of those diagrams so I can finally experience RGB bliss after all of these months.
http://www.intersil.com/data/fn/fn7018.pdf
Seems easy enough to me. The pin functions are described in plain English on page 3. I'm impressed that it doesn't need a crystal or a separate clock signal. According to the table, a 681k resistor on pin 6 puts it in NTSC timing by default. There's only one ground, and only one input for composite video. It's ridiculously simple.
Quote from: zedrein on May 08, 2009, 06:47:31 AM
I've just read all of this jibberish about building a circuit for the EL1881 sync-separator, and by God, I am having a really hard time understanding it. Here's a link to the data sheet for the chip, someone please help me translate some of those diagrams so I can finally experience RGB bliss after all of these months.
http://www.intersil.com/data/fn/fn7018.pdf
Please explain why you are building a circuit off of this IC? ???
Quote from: RGB32E on May 08, 2009, 02:53:27 PM
Quote from: zedrein on May 08, 2009, 06:47:31 AM
I've just read all of this jibberish about building a circuit for the EL1881 sync-separator, and by God, I am having a really hard time understanding it. Here's a link to the data sheet for the chip, someone please help me translate some of those diagrams so I can finally experience RGB bliss after all of these months.
http://www.intersil.com/data/fn/fn7018.pdf
Please explain why you are building a circuit off of this IC? ???
Why wouldn't he? The EL1881 is the Intersil equivalent of an LM1881, is it not?
zedrein,
http://www.gamesx.com/misctech/lm1881.htm
Why using that outdated one from the Elantec era when you can use the ISL59885 from Intersil (they bought Elantec)? It outputs both horizontal and vertical sync directly without need of extra stuff and supports more things, I'm going to try it soon as many people talk very good of them.
Quote from: kendrick on May 08, 2009, 07:15:12 AM
Seems easy enough to me. The pin functions are described in plain English on page 3. I'm impressed that it doesn't need a crystal or a separate clock signal. According to the table, a 681k resistor on pin 6 puts it in NTSC timing by default. There's only one ground, and only one input for composite video. It's ridiculously simple.
Sorry, I'm just no good with electronics at all. I am more of a guy that needs to physically see how something like this is built rather than in diagrams.
Don't sweat it, I had trouble with IC packages at first. The best way to approach building a circuit around an IC is to connect other components to one pin at a time. Make sure you connect the ground pin first, work your way around every other pin one at a time, and then connect the power connection last. This isn't applicable to every video encoding chip because of multiple grounds, but since this chip has only the one common ground you should be fine.
Look for the dimple or the dot that indicates which one is pin 1. On most TTL chips, pin 1 is also ground and is good place to start. Then everything is numbered sequentially around the outer edge of the chip.
Once you get comfortable with ICs, you'll see that the abstract diagram is the best way to understand the connections, especially from a troubleshooting standpoint. Dependent functions are usually put on opposite sides of the chip so that they're easy to wire, but in the abstract diagram they have to be next to each other so that they go into the same system. Good luck.