T&L Publications

I think PWM and PDM are the same.<p>With just ON and OFF, there are only two variables, ratio of ON to OFF and frequency. PWM has a fixed frequency and varies the ratio. PFM has a fixed ON time and varies the frequency to change ratio.<p>Did the Forrest Mims List have PFM (Pulse Frequency Modulation...

Stay with the Variac.<p>With any kind of AC duty cycle controller into filtered DC, the output voltage will always try to approach peak at anything more than 45% (with current pulses getting narrower and higher). At less than 45% the output voltage will adjust, but will vary depending on load (bad r...

250V at 50A ... We have an UPS at work about that size. It is about the size of the large refrigerator! The battery box about the size of 3 refrigerators. The 12V batteries are in series.<p>Can I ask a question? What do you want such a beast for? For variable speed of a BIG motor? I would suggest SC...

An Amp meter goes in series. Disconnent one wire from solar cell to battery, one Amp meter lead connects to the wire, the other lead goes to where the wire used to be connected. If an analog Amp meter, watch polarity!<p>If solar cells are 20 - 25 cable feet away, then that's 40 - 50 ft. of wire that...

How much frequency range?
How many Amps?

perfectbite,<p>That was haklesup. I wouldn't bother measuring reverse current, just put the diodes in for GPs. (a diode is cheap, so who cares if there's leakage without it as long as the solar panel produces current when lit?)<p>If I did want to measure it, I'd set my DMM for Amps, and put it serie...

Externet,<p>8 * 12V = 96V
115V half wave rectified equalls about 57V<p>But filtered:
115Vrms * 1.414 = 163V ... poof!<p>10 fans with fullwave rectifier is OK, but DO NOT filter.<p>C U L -

(I took too long typing, there were no replies when I started.) :( <p>If the cells says 500mA, and the box says 300mA; then they didn't pass the test at the factory. No problem, except the factory couldn't sell them as 500mA units, and sold them into hobby market.<p>What haklesup said is true too. H...

0.32A * 24H = 7.68AH is daily fan consumption.<p>Assume a cloudy day in winter (yeah I know, rare in LV) makes a 16 hour night. Then:<p>0.32A * 16H = 5.12AH from battery before next morning. Your 8AH idea was about right.<p>To recharge the battery in 8 hours, the current needed is:<p>5.12AH / 8H = 0...

How so? From what I've read, nobody was expected to finish! Now everybody, including DARPA, knows where the weaknesses are. That's why is was declared a success.

Its morning here, I'll take a stab at it. Sleep easy.

Is that 24 Volts AC or DC?<p>Probably AC, and by the time you buy parts it would be around $4 per solenoid. DC a little less.<p>Yes you need opto-couplers.<p>I can draw a circuit, but need to know if AC or DC.

I don't think direct transfer is going to work for SMD. I second amuron, do a photo resist.

Check the Ramsey ad in N & V mag. (Pages 14 and 15 in Feb 2004 issue) (probably others in back)
AM is less expensive.

Pocket sized AM/FM radio ($6.95 variety), and an FM transmitter kit should do it.