Search found 134 matches

by Chris Foley
Sun Aug 31, 2003 6:13 pm
Forum: General Discussion
Topic: Variable frequency drive
Replies: 9
Views: 2904

Re: Variable frequency drive

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...
by Chris Foley
Fri Aug 29, 2003 10:41 am
Forum: General Discussion
Topic: Debouncing Switches
Replies: 7
Views: 3517

Re: Debouncing Switches

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...
by Chris Foley
Sun Aug 24, 2003 8:17 pm
Forum: General Discussion
Topic: Reverse Polarity on 555 timer???
Replies: 16
Views: 7358

Re: Reverse Polarity on 555 timer???

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...
by Chris Foley
Fri Aug 22, 2003 6:28 pm
Forum: General Discussion
Topic: Reverse Polarity on 555 timer???
Replies: 16
Views: 7358

Re: Reverse Polarity on 555 timer???

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...
by Chris Foley
Sun Aug 17, 2003 8:32 am
Forum: General Discussion
Topic: Functional Generator Question
Replies: 9
Views: 4913

Re: Functional Generator Question

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...
by Chris Foley
Thu Aug 14, 2003 8:53 pm
Forum: General Discussion
Topic: Need oscillator circuit
Replies: 10
Views: 4779

Re: Need oscillator circuit

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>
by Chris Foley
Thu Aug 14, 2003 8:41 pm
Forum: General Discussion
Topic: 27C256/27C512 SOIC.TSOP EEPROMS QUESTION
Replies: 2
Views: 1573

Re: 27C256/27C512 SOIC.TSOP EEPROMS QUESTION

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...
by Chris Foley
Tue Aug 12, 2003 8:36 pm
Forum: General Discussion
Topic: Need oscillator circuit
Replies: 10
Views: 4779

Re: Need oscillator circuit

(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...
by Chris Foley
Sun Aug 10, 2003 6:01 pm
Forum: General Discussion
Topic: resistor problem on uC
Replies: 2
Views: 900

Re: resistor problem on uC

Bass-ackwards?
by Chris Foley
Thu Aug 07, 2003 9:35 am
Forum: General Discussion
Topic: Light-dependent resistor
Replies: 8
Views: 1900

Re: Light-dependent resistor

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.
by Chris Foley
Wed Aug 06, 2003 7:29 pm
Forum: General Discussion
Topic: Light-dependent resistor
Replies: 8
Views: 1900

Re: Light-dependent resistor

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 ...
by Chris Foley
Mon Aug 04, 2003 12:54 pm
Forum: General Discussion
Topic: bcd switch info
Replies: 4
Views: 1152

Re: bcd switch info

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...
by Chris Foley
Mon Aug 04, 2003 12:43 pm
Forum: General Discussion
Topic: 5 sided semi enclosures
Replies: 2
Views: 880

Re: 5 sided semi enclosures

An inexpensive source for electronics enclosures is LMB:<p>http://www.lmbheeger.com/<p>Happy hunting.
by Chris Foley
Fri Aug 01, 2003 2:41 pm
Forum: General Discussion
Topic: Buying a digital multimeter
Replies: 16
Views: 4001

Re: Buying a digital multimeter

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 tend to s...
by Chris Foley
Thu Jul 31, 2003 11:32 am
Forum: General Discussion
Topic: Here's How to Solve Our money Problems!
Replies: 21
Views: 5966

Re: Here's How to Solve Our money Problems!

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...