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Hi, Denny. AC variable speed drives are now relatively inexpensive and really pretty reliable. When you're doing this, the price of failure is usually a minimum of a smoked motor, plus whatever you're working on, plus the possibility of damaging the machine itself. Consider looking at some of the Au...

If you're reading the switches with a PIC, you just use a software debounce (if it's there a certain number of times in a row, it must be there). However, if you're using the inputs for TTL or other discrete logic, you will want to have a hardware debounce.<p>If you're just getting one input, you co...

The brief answer to your question is, try the 1N5817 schottky rectifier diode if you're worried about voltage drop. It has a PRV of 20V, it's good for 1A, and its V(f) is half that of the 1N4001 across the board.<p>Your basic problem, though, has to do with the voltage and current budget for a 9V ba...

Hi, Todd. You probably do want to add a protection diode. Try a Schottky -- real-world small current voltage drops across Schottky diodes are in the 0.15V-0.25V region (10 mA or so). By the time a 9V battery gets down to the area where this would make a difference (5V for a regular 555), your 9V bat...

Somebody has already thought of your idea. You could do worse than the MAX038 kit based on the Electronics Australia August 1996 article. DIY 101 includes absolutely everything you need to make what you want, including plastic case. It's available for 75 bucks or so from a number of sources, includi...

Maximum VCO frequency for the 'HC4046 is 12 MHz at TTL voltage levels. Plain HCMOS just doesn't go there. If anyone else has a better PLL chip that'll do 42MHz, I'd like to know.<p>[ August 14, 2003: Message edited by: Chris Foley ]</p>

The parts you're looking for (27C256, 27C512) are available in ceramic DIP, plastic DIP, SOIC, TSOP, and PLCC packages. However, the erasure window is only available in the CERDIP package, as far as I can tell. These EPROMS are called OTP, for one-time programmable. Somewhere along the line long ago...

(NOTE: TYPO ALERT -- I called out A CD74ACT161 as a CD74HC161 below. Typo corrected -- sorry. HCMOS chips don't go that fast -- counter chips, either)<p>I'm not sure you're heading in the right direction here. The 74HC4060 has a couple of pins that can be used with either an RC or a crystal as an os...

Bass-ackwards?

There is a term called the absorption coefficient which could refer to photoresistors, but unless your book was a college-level physics textbook, it's not what you're talking about.

Hi, Brad. Can you tell us what kind of book you got that term from? If it's an intro-type electronics book, they might just be referring to the ratio between R(on) and R(off). A higher ratio would mean the photocell would be easier to use as an on/off indicator.<p>By the way, found out that Clairex ...

We'd need more information to be sure, but as it says in a previous post, the extra pin is probably another common or (if it's a large switch or thumbwheel) an inverted common. If it's a six-pin DIP-type with either a screwdriver-adjust slot or a small dial, you might have something like this:<p> ht...

An inexpensive source for electronics enclosures is LMB:<p>http://www.lmbheeger.com/<p>Happy hunting.

I'd tend to agree with Lien -- you don't always get what you pay for, but you always pay for what you get. The "dime store" DMMs (I've had several, none still alive) will tend to have disappointingly inaccurate readings, especially on the AC voltage and current and on resistance. They also...

There are a finite but very large and growing number of newsgroups which cover these issues, and provide a forum for people who feel strongly about issues to have a chance to speak out.<p>Tux -- this is a special interest bulletin board, not a newsgroup. Whether we agree with you or not, you have to...