T&L Publications

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...

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.

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...

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.

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.

I'm going to guess that what you are looking for are metal film resistors.

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...

...and, if the series diode works, you probably don't need the relay.

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...

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...

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.

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 b...

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...

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.

>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 ...