From: mjohnson at netcom4.Netcom.COM (Mark Johnson) If you know what you are doing, you can build wirewrapped boards that operate above 100MHz. I myself have done so; I've got a couple that run at 150MHz with no trouble. On the other hand, if you don't know what you are doing, you can screw up almost any technology, including wire wrap, printed circuit board, proto-plugboard, and airbridge. "It's not the sword, it's the swordsman" "It's not the sword, it's the swordsman" "It's not the sword, it's the swordsman" "It's not the sword, it's the swordsman" Here are a few ways to screw up a wirewrapped project, so as to make it fail even at low frequencies: 1. Don't use a board with a ground plane. 2. When wrapping the positive and negative supply pins of IC's, use wires longer than 0.75 inch. The longer the better; these aren't high frequency signals, they are just DC supplies. 3. Don't install ceramic bypass capacitors at every chip 4. Use digital logic chips having very fast edge speeds (dV/dt), such as 74S, 74AS, 74F, and, best of all, 74FACT. 5. Daisy chain the ground wires: wrap from the off-board ground connector, to the ground pin on the first chip, to the ground pin on the second chip, to the ground pin on the third chip, and so forth. 6. Freely mix analog and digital circuitry on a wirewrap board, Be sure the analog part us used as a routing area for digital signal wires, and vice versa. Share supply and ground connections between the two. If you scrupulously follow these rules, then you can brag to your friends that you have built a wirewrap board that failed, not at 20MHz, but at 1MHz. Won'tthey be impressed!
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