Search found 1747 matches
- Wed Mar 24, 2004 8:23 pm
- Forum: General Discussion
- Topic: How a Power inverter works?
- Replies: 9
- Views: 3924
Re: How a Power inverter works?
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...
- Wed Mar 24, 2004 7:56 pm
- Forum: General Discussion
- Topic: solar power questions
- Replies: 13
- Views: 5811
Re: solar power questions
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...
- Wed Mar 24, 2004 3:26 am
- Forum: General Discussion
- Topic: Varying AC frequency
- Replies: 11
- Views: 5586
Re: Varying AC frequency
How much frequency range?
How many Amps?
How many Amps?
- Thu Mar 18, 2004 2:46 am
- Forum: General Discussion
- Topic: solar power questions
- Replies: 13
- Views: 5811
Re: solar power questions
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...
- Wed Mar 17, 2004 8:34 pm
- Forum: General Discussion
- Topic: Half wave rectified mains...
- Replies: 6
- Views: 2909
Re: Half wave rectified mains...
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 -
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 -
- Wed Mar 17, 2004 8:09 pm
- Forum: General Discussion
- Topic: solar power questions
- Replies: 13
- Views: 5811
Re: solar power questions
(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...
- Wed Mar 17, 2004 7:44 pm
- Forum: General Discussion
- Topic: solar power questions
- Replies: 13
- Views: 5811
Re: solar power questions
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...
- Tue Mar 16, 2004 5:56 pm
- Forum: Robotics
- Topic: Big Darpa race was all did not finish
- Replies: 1
- Views: 2876
Re: Big Darpa race was all did not finish
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.
- Sat Mar 13, 2004 8:19 pm
- Forum: General Discussion
- Topic: solenoid valve driver
- Replies: 10
- Views: 3971
Re: solenoid valve driver
Its morning here, I'll take a stab at it. Sleep easy.
- Sat Mar 13, 2004 7:03 pm
- Forum: General Discussion
- Topic: solenoid valve driver
- Replies: 10
- Views: 3971
Re: solenoid valve driver
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.
- Fri Mar 12, 2004 5:42 am
- Forum: General Discussion
- Topic: Using transparencys for pcbs?
- Replies: 9
- Views: 3840
Re: Using transparencys for pcbs?
I don't think direct transfer is going to work for SMD. I second amuron, do a photo resist.
- Thu Mar 11, 2004 7:38 pm
- Forum: General Discussion
- Topic: wireless ear bud
- Replies: 13
- Views: 5610
Re: wireless ear bud
Check the Ramsey ad in N & V mag. (Pages 14 and 15 in Feb 2004 issue) (probably others in back)
AM is less expensive.
AM is less expensive.
- Thu Mar 11, 2004 4:05 am
- Forum: General Discussion
- Topic: wireless ear bud
- Replies: 13
- Views: 5610
Re: wireless ear bud
Pocket sized AM/FM radio ($6.95 variety), and an FM transmitter kit should do it.
- Wed Mar 10, 2004 5:20 am
- Forum: General Discussion
- Topic: Las Vegas Test Specification
- Replies: 5
- Views: 2561
Re: Las Vegas Test Specification
Las Vegas Spec: You send money, he sends motors. Less than 50% pass a test.
- Mon Mar 08, 2004 8:10 pm
- Forum: General Discussion
- Topic: Pre-amp Circuit Help
- Replies: 21
- Views: 7895
Re: Pre-amp Circuit Help
<1mV at close range, so let's say we want to detect down to 100uV for farther range. Pick 6V peak as target. 6V / 100uV = 60000 (96dB). Call it 100dB (100000) to make sure.<p>3 op amps, each with a gain of 10, amplifies signal to 0.1V. (70KHz * 10 = 700000 so might be possible with 741s, better amps...