|MadSci Network: Engineering|
Hi Jay! Welcome to the hallowed halls of the CMOS experimenter! I'm glad to be able to help you. While I could just give you a parts list and circuit diagram, I respect your willingness to learn the how and why's of circuit design on your own. The one book I would recommend highly, be you a beginner or well advanced, is the "CMOS Cookbook" by Don Lancaster. It contains a brief history of CMOS, then gets into the actual package types (4518 dual synchronous divide-by-10 counter, 4011 quad 2-input NAND gate, etc.) proper circuit design techniques, hints, tricks, clocked logic, sample circuits, and much, much more. It is available from various sources, Amazon.com being one, for about $22. I bought mine back in 1977, but a new (1997), updated version is now in print. $22 bucks may sound like a lot but, when you consider I have used mine for about 23 years and it cost me $7.95, that comes out to about 35 cents per year! Not too bad. Other books are available at places like Radio Shack. When you need to get very detailed specifications, you can go directly to the manufacturer. Texas Instruments ( http://www.ti.com ), National Semiconductor ( http://www.national.com ) and others, have on-line access to the latest info on their products including specification sheets, application notes (great resource - some include complete circuits for various applications; others discuss the theory of operation of Operational Amplifiers, Phase-Locked Loops, power supply regulation, and more). They also publish their own databooks which can be had in either soft-cover or CD-ROM for free or at a nominal charge. I suggest you salvage an AT power supply from an old desktop computer. These power supplies are ideal for experimenting. They provide both 5 volts DC and 12 volts DC. Also, get an 'experimenters breadboard' at Radio Shack, the one with the power supply banana plugs mounted on it. With one of these, you can plug multiple CMOS devices directly into the board and make your connections with 22 gauge hook-up wire. Get several colors. I use red for the power supply positive, black for the negative, and green for everything else. It makes it much easier to check your wiring and trouble-shoot the circuit. You can make changes to your circuit easily with a braedboard, and it keeps things relatively neat. Plus, it's a heck of a lot easier, less time consuming, and cheaper in the long run than buying sockets for your CMOS, mounting them on a circuit board and wire- wrapping or soldering your connections. Once you've completed the design AND testing of your circuit, THEN you can make it permanent on a socketed circuit board using wire-wrapped connections. Later on, you can buy a kit and etch your own circuit boards on copper-clad fibreglass (also available at Radio Shack). With this process, you place circles and other shapes of an etch resist material, where you want to put your sockets and other components, and 'connect the dots' with a special etch resist pen. The circles, etc. come on sheets which you transfer to the board by positioning the sheet on the board and rubbing the back side of the circle with a ballpoint pen or other smooth-tipped tool. The circle will stick to the copper. Once you have your circuit 'drawn' on the board, the board is placed in the etching solution (ferric chloride - CAUTION! HIGHLY CORROSIVE!), which dissolves the uncovered copper; that which has no circles or lines over it. When the etching is done (you can tell by watching it dissolve the copper), you end up with a completed circuit board - ready for component mounting and soldering. I use a computer to 'draw' my circuits to actual size, print it out on a laser printer, make a photographic negative of it, place the negative over a specially-coated photo resist copper-clad board, and expose it to ultra- violet light for about 15 minutes. The ultra-violet light polymerizes the coating under the clear areas of the photographic film, making them impervious to the ferric chloride etchant. It's obviously a much more involved process, but the computer lets me draw much thinner (and straighter) lines than can be done with a pen, resulting in a much more compact and neat circuit board. If I can be of more help, contact me directly at Karl-Kolbus@email.msn.com Also, if you wish, email me a rough drawing of your circuit, with your component choices (CMOS part numbers) and I may be able to make some suggestions to improve it, or make it work if you're running into trouble. Good Luck! Your not-so-mad scientist, Karl Kolbus
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