Search found 525 matches

by sofaspud
Mon Jun 28, 2004 11:29 pm
Forum: General Discussion
Topic: electronic scarecrow
Replies: 25
Views: 3562

Re: electronic scarecrow

Might work, but then I'll need to ask for a way to deter that in-heat cougar. Not really the route I want to take. I don't need 360° coverage. The sensor can be placed at one end of the container, so the coverage only needs to be ~45-90°. I had also thought of sound effects, but it was a rattlesnake...
by sofaspud
Mon Jun 28, 2004 5:44 pm
Forum: General Discussion
Topic: Flexible Thermoelectric Coolers Anyone?
Replies: 13
Views: 1923

Re: Flexible Thermoelectric Coolers Anyone?

dacflyer,
True those overseas subs cost an arm & a leg, but you can get a year (12 issues) of the EPE online version for $10.99. Each issue is about a 5 meg d/l.
by sofaspud
Mon Jun 28, 2004 1:16 pm
Forum: General Discussion
Topic: electronic scarecrow
Replies: 25
Views: 3562

electronic scarecrow

This is a junkbox-type project I've been brainstorming for a while, and I'd appreciate any ideas from this group. What I would like to build is a battery-powered circuit that I can take camping. On those trips my food is kept in an ice chest or lidded plastic tub. Bears aren't a problem; for the mos...
by sofaspud
Mon Jun 28, 2004 12:56 pm
Forum: General Discussion
Topic: Flexible Thermoelectric Coolers Anyone?
Replies: 13
Views: 1923

Re: Flexible Thermoelectric Coolers Anyone?

Everyday Practical Electronics is a British publication. I have seen it before on the newstand at my local Barnes & Noble bookstore. EPE also has an online version found at http://www.epemag.com/, where that June 2004 issue can be downloaded for about $5.
by sofaspud
Sun Jun 27, 2004 8:15 pm
Forum: General Discussion
Topic: Flexible Thermoelectric Coolers Anyone?
Replies: 13
Views: 1923

Re: Flexible Thermoelectric Coolers Anyone?

I have never seen or heard of a flexible Peltier device. Everyday Practical Electronics magazine had a beverage can cooler project in their June 2004 issue. You might want to check that out.
by sofaspud
Sun Jun 27, 2004 7:56 pm
Forum: General Discussion
Topic: High-quality resistors
Replies: 14
Views: 1861

Re: High-quality resistors

I'm going to guess that what you are looking for are metal film resistors.
by sofaspud
Thu Jun 24, 2004 9:43 am
Forum: General Discussion
Topic: Car battery Backup Circuit
Replies: 12
Views: 1744

Re: Car battery Backup Circuit

If you go with a microcontroller, then any worries with the battery recharge can be put to rest by employing a second timer circuit. For example (a lot depends on your driving habits), the recharge can be timed to shut off after fifteen minutes of drive time, or set for 2 hours total per day, or 1 h...
by sofaspud
Wed Jun 23, 2004 10:09 pm
Forum: General Discussion
Topic: Car battery Backup Circuit
Replies: 12
Views: 1744

Re: Car battery Backup Circuit

...and, if the series diode works, you probably don't need the relay. :roll:
by sofaspud
Wed Jun 23, 2004 9:50 pm
Forum: General Discussion
Topic: Car battery Backup Circuit
Replies: 12
Views: 1744

Re: Car battery Backup Circuit

I took a look at those circuits. The bottom circuit provides a very basic schematic. Again, if it were me, I would put the relay on a timer rather than energizing and de-energizing it at the same time as the starter. That way I know I won't have any issues with voltage drops when cranking the engine...
by sofaspud
Wed Jun 23, 2004 7:35 pm
Forum: General Discussion
Topic: Car battery Backup Circuit
Replies: 12
Views: 1744

Re: Car battery Backup Circuit

Seems to me you're on the right track. I don't really have a circuit I can point you to. If your backup battery is 12V/7Ah it shouldn't be a problem finding a recharge circuit. I think it would be reasonably easy to implement a manual switch that would toggle between the vehicle supply and the backu...
by sofaspud
Tue Jun 15, 2004 1:14 pm
Forum: General Discussion
Topic: test circuit schematic
Replies: 5
Views: 851

Re: test circuit schematic

Obtain the specs on the nichrome wire and get the "melting current". Replace the 12 volt battery with one of smaller voltage, with a current-limiting resistor in series with an LED, that will allow the LED to light w/o providing enough voltage & current to melt the wire.
by sofaspud
Tue Jun 15, 2004 12:58 pm
Forum: General Discussion
Topic: line-level audio to preamp level
Replies: 3
Views: 634

Re: line-level audio to preamp level

I'm not exactly sure either of what you want to put together. If you have an amp separate from the head unit then I don't think there would be a problem tapping into the amp inputs with a different audio source. But you say "I don't have line-level inputs" so I'm wondering if your amp is being fed a...
by sofaspud
Mon May 31, 2004 1:47 am
Forum: General Discussion
Topic: Simple LED display
Replies: 4
Views: 855

Re: Simple LED display

There are a couple more things I would take into account. First of all, I'm assuming that all these sensor switches will be in parallel and there will always be an LED lit to indicate status (i.e. green=closed/red=open). Each switch/LED combo makes a complete circuit. At 20mA per LED, you are alread...
by sofaspud
Fri May 28, 2004 5:46 pm
Forum: General Discussion
Topic: Charging 12V Battery while riding Bicycle
Replies: 19
Views: 3437

Re: Charging 12V Battery while riding Bicycle

If you have a 6 volt AC output, could you use a voltage doubler to achieve 12 volts and still have sufficient current to charge your battery? Seems like it might be worth a try.
by sofaspud
Fri May 28, 2004 5:12 pm
Forum: General Discussion
Topic: Hand Crank Generator.
Replies: 9
Views: 1478

Re: Hand Crank Generator.

>Does anyone know how to compare Farads to mAh. In other words, How long would a 1F cap supply 1mA to a load.<p>This seems fairly easy - I'll probably get it wrong! But anyway, the answer is found from the RC time constant (t). At 5 volts, a resistive load of 5k ohms will draw 1mA. t=RC which would ...