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Date Posted |
Forum
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RE: What Android apps do you find useful?
Multicon is the best app I have. Put 4 icons in the same space as one icon normally takes up. Shows the same icon only smaller. Put 4 times as many icons on home screen.
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LScamper
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05/11/13 08:48am |
Technology Corner
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RE: how to safely deenergize capacitor
Capacitor self charging is real. It can be deadly when using high voltage capacitors!
A few sources of info:
http://en.wikipedia.org/wiki/Dielectric_absorption
http://blog.shuningbian.net/2005/04/self-charging-behaviour-of-electrolyte.php
And this one lots of you engineers will read with fond memories by Bob Pease -- What's all this soakage stuff, anyhow?
http://electronicdesign.com/analog/whats-all-soakage-stuff-anyhow
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LScamper
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05/06/13 09:23am |
Tech Issues
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RE: Monitor Panel - All Tanks Read Full
Test procedure
http://www.kibenterprises.com/troubleshoot.html#troubleshooting
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LScamper
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03/06/13 03:23pm |
Tech Issues
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RE: A walk down memory lane
Still have my 1976 TRS80 in my shed. I'm sure it does not work anymore. Complete with 4k memory and 48k floppy disk drives. Did wonderful graphics of stick men actually moving! Could store programs on a tape recorder and sometimes it worked. Connected to main frame at work using Bell 103 acoustic 300 baud modem. Not much has changed with computers since then, they still only work when they want to.
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LScamper
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03/05/13 10:08am |
Technology Corner
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RE: Converter Left On Powered by Inverter--Measurements
Salvo wrote:
"No, no, no! The converter has a bridge rectifier. Power is consumed not only at the positive half cycle, but also on the negative half cycle."
Correct!
When thinking of power factor in the usual way with an inductive load or even capacitive load energy is stored and then returned as HiTech says. However with a rectifier (switch) in the circuit energy only goes one way. There is no returned energy.
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LScamper
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02/13/13 03:21pm |
Tech Issues
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RE: Is anyone using ultra capacitors in solar with RV batteries?
Don wrote:
"The link I provided early in the thread has 12 and 24 volt units. http://www.koldban.com/Kapower_Specifications_s/29.htm"
Sorry I did not read the thread close enough and did not see your post.
It is interesting that you don't need to balance their caps in series. Their leakage current goes up and they become self balancing. Also interesting is that you need to keep them above 4 volts all the time.
I did make a math error because I was not thinking! I said you need 6 each 2.7V caps but you most likely need 36. Salvo says 25 but that only gets you to 13.5V. 36 gets to a safer 16.2V. This also drops the AH by 1/6.
Maybe some day the price will come down to what we can use but I don't think I'll still be RVing by then.
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LScamper
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02/05/13 06:11pm |
Tech Issues
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RE: Is anyone using ultra capacitors in solar with RV batteries?
Many problems with ultra caps!
First is cost, about $65 to $100 each 2000f, 2.7V cap. From DigiKey. You need 6 of them to get battery voltage and only provides 1.7 AH.
Next big problem is charging them in series. Because of capacitance tolerance and changes with time and temperature there has to be some kind of balancing circuit to keep from overcharging the lower capacity ones in the string, either active or passive. Passive constantly discharges the caps, active is expensive.
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LScamper
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02/05/13 10:48am |
Tech Issues
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RE: Is anyone using ultra capacitors in solar with RV batteries?
Mark wrote:
" Here's the math if anybody wants to re-check for me;
2000 Farads x 12.5 V = 25000 As
25000 As ÷ 3600 = 6.94 Ah"
Without some more electronics you can only draw the voltage down about 3V, say 14.5 > 11.5, which is delta of 3V. So the usable AH is about 1.7AH.
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LScamper
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02/04/13 09:50am |
Tech Issues
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RE: MSW inverter output voltage regulation
Wayne wrote:
“I've found the Kill-A-Watt to be "pretty good" at measuring MSW voltage. At the higher inverter DC voltages, the KAW and my true RMS voltmeter agree to less than a volt. At the lower DC voltages where the output is close to a square wave the KAW reads 4 to 5 volts higher than the voltmeter. The voltmeter reads about 2 volts higher than what the scope says. Don't know which one to believe there. The KAW says "DC" for the MSW frequency.”
I don’t know which one to believe either but if you are using a Fluke meter that would be the one. The scope has an 8-bit digitizer and is rated at 2% gain accuracy. If it makes 7bits that’s good and about 1%. So your voltmeter and scope are within about 2%. The meter must have at least .1% accuracy so that is the one to believe. Still pretty amazing that a scope can make that close of a measurement! Not like the analog scope days.
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LScamper
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01/28/13 05:09pm |
Tech Issues
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RE: MSW inverter output voltage regulation
Very impressive looking FFT plots.
It would be nice to see the same thing plotted as dBVrms on the vertical scale and low enough gain to see the fundamental. Also maybe the horizontal scale should be around 250 Hz/Div? I suspect that lots if not most of the higher order harmonics are really down in the noise, can’t tell from this plot.
Nice scope, I have an older Rigol, can’t beat it for the money. If anyone is looking for a scope the Rigol 100 MHz model is selling for around $400.00.
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LScamper
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01/28/13 04:04pm |
Tech Issues
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RE: How to stop inaccurate black tank levels on the monitor?
Horst Miricle Probes worked for me on the grey tank but not on the black tank.
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LScamper
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01/02/13 09:19am |
Tech Issues
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RE: 220 volts from 5500 watt 120v genny question
Correct my last post
If the gen is 220V, split phase for two each 120V outputs 180 degrees out of phase a transformer with two 120V primaries wire in series will still work. That is a 1:1 transformer.
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LScamper
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12/31/12 12:01pm |
Tech Issues
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RE: 220 volts from 5500 watt 120v genny question
If the gen is 220V, split phase for two each 120V outputs 180 degrees out of phase a transformer with two 120V primaries wire in reverse phase will still work.
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LScamper
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12/31/12 11:41am |
Tech Issues
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RE: 220 volts from 5500 watt 120v genny question
5 KVA transformers
http://www.automationdirect.com/adc/Shopping/Catalog/Power_Products_%28Electrical%29/Power_Transformers/Encapsulated_Transformers_%28NEMA_Rated%29/480x240_VAC_to_240X120_VAC/C1F005LES?utm_source=google&utm_medium=product-search&gclid=CNfsodqPxbQCFQ_hQgodJ3IAMA
Lots of 5 KVA transformers on Ebay from about $100 up.
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LScamper
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12/31/12 10:20am |
Tech Issues
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RE: How would you detect a NEUTRAL GROUND Reversal?
gijoecam wrote:
"And again, even if the pedestal is wired as a sub-panel (i.e. the ground and neutral are not bonded), and the neutral and ground are crossed, I still fail to see the potential for a dangerous condition... "
Read my post several pages ago. Read the part about the coax getting hot!! This is due to the difference in voltage between the hot and the neutral under load. The coax now shares the return current and heats up. If there is a bad connection on the coax like maybe only a few strands connected and it is in the wall somewhere it could cause a fire.
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LScamper
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12/12/12 09:09am |
Tech Issues
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RE: How would you detect a NEUTRAL GROUND Reversal?
In thinking about my last post - depending on how the cable coax was connected in the camper there could be a slightly high resistance connection. This could get hot and be a fire hazard.
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LScamper
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12/11/12 11:16am |
Tech Issues
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RE: How would you detect a NEUTRAL GROUND Reversal?
I had one experience in a campground where the neutral and ground were reversed. This is how I found that there was a problem. After plugging into a 30A circuit all seemed OK. Everything worked as expected. Next I connected the coax for cable TV. When I connected it I saw a small spark! After a short time the cable got warm. After thinking about this I realized that there must be current on the ground wire in the campground. There will always be a voltage drop on the neutral wire if there is any load on the system. There should never be a voltage drop on the ground wire. Connecting the coax from the camper to the cable outlet at the campground connected the ground wire in the camper to the ground at the campground post. If the neutral and ground were reversed there would be current on the campground ground wire causing a voltage drop. This voltage drop would be seen from the camper ground to the campground post and drive a current in the coax cable. It would be a small voltage maybe a few volts but the current could be vary high.
So one way to tell if the neutral and ground are reversed you need to measure the voltage from the campground ground wire to a good ground like maybe a water pipe. Another way might be by measuring the current on the cable coax, it should be 0.
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LScamper
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12/11/12 11:04am |
Tech Issues
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RE: Impedance matching batteries
MEXICOWANDERER wrote:
"Just the ticket to mimic nearby lightning strikes, chemical factory rocket fuel detonations, and a General Electric J79 engine from an F 104 Starfighter. This amplifier/speaker combination MUST be powered by a gold plated electrical receptacle pricetagged at eleven hundred dollars, or, it, well it, it doesn't make the grade."
At times when things did not go correctly it looked like lightning strikes! No speaker, it would be one heck of a speaker. Yes the system was a high priced item.
More memories - my first job out of high school was machining parts for the J79 fuel system at Parker Hannifin.
An old write-up of the system at:
http://library.lanl.gov/cgi-bin/getfile?00236711.pdf
Sorry for getting off thread.
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LScamper
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12/09/12 09:14am |
Tech Issues
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RE: Impedance matching batteries
"Sounds like a broadcast radio station engineering position."
It would take about 100 radio stations just to drive the output stage of this system!
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LScamper
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12/08/12 10:36am |
Tech Issues
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RE: Impedance matching batteries
Spent most of my life working with tubes. Try a 2.5 GW (that is 2500 MW) amplifier chain. One hundred Machlett ML8618s running 35 Kv plate pulsed to 800 A plate current each. Filament power 2.5 kW each.
Did the dump thing as a kid also.
Brings back memories!
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LScamper
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12/08/12 10:07am |
Tech Issues
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