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 > Your search for posts made by 'LScamper' found 67 matches.

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  Subject Author Date Posted Forum
RE: Mushroom Cloud Over Mexico LED Magic Smoke Tomorrow

"I gotta try it. (4) 33 volt LED chips in series. (1) 5 amp 1KV rectifier in series for a guarantee (1) 100uf 450 volt electrolytic cap connected inside the rectifier circuit. Plugger into a wall socket. I shall wear a safety shield mask and gloves.... Line voltage in Mexico is rated 127 vac." 4 x 33V = 132V voltage across LEDs 1.414 x 127 = 180V!! "Mushroom Cloud Over Mexico LED Magic Smoke Tomorrow"!!
LScamper 08/13/14 04:50pm Tech Issues
RE: Sizing MOSFET Heat Sink

Long day Salvo? "Max power at 50A is: P_max = 4.5 mohm * 50A = 2.25 W" P_max = 4.5 mOhm * 50A * 50A P-max = 11.25W Have a great day!
LScamper 07/12/14 02:00pm Tech Issues
RE: Sizing MOSFET Heat Sink

Don't need much of a heat sink for this little power. This will give you some idea of what to use. Clicky
LScamper 07/12/14 08:53am Tech Issues
RE: ADJUSTABLE POWER SUPPLY CUTIE

12V 100W led http://www.youtube.com/watch?v=CxnP-6EZ3ZQ Variable DC Power Supply 30v 5a http://www.youtube.com/watch?v=4H6iwiPIaJI High Power LED Forward Voltage Tutorial http://www.youtube.com/watch?v=S5IICsTwTYE 305 DC LAB POWER SUPPLY REVIEW http://www.youtube.com/watch?v=A3yZTSAd8YE
LScamper 05/24/14 11:22am Tech Issues
Battery infromation

This information is for AAs but most of it will scale to 12V lead acid batteries. May be interesting. Clicky
LScamper 05/21/14 07:58pm Tech Issues
AA battery testing

This is a cheap way to test your AA batteries to see if they are charged. Wonder if it would work with lead acid batteries? Clicky
LScamper 05/21/14 05:24pm Tech Issues
RE: QUESTIONS re: MEGA-WATT 33-AMP POWER SUPPLY

Not an answer, just a question. The statement that they will burn out if parallel makes me wonder why. Is it that if one supply is set for a higher output voltage than the other it will supply a high current back into the lower voltage supply? (The lower voltage supply can sink current as well as supply it). If not then it seems that the higher voltage supply would just supply all the current and be limited as if only one supply is not connected. The lower voltage supply would do nothing. If it is because the supply can sink current as well as source it there could be a big problem. How would the supply know if another supply was parallel with it or a battery instead of another supply? If the battery voltage was higher than the supply would it burn out the supply? Just wondering.
LScamper 04/29/14 07:54pm Tech Issues
RE: Coaxial TV cable getting hot / Need wiring diagram

Plug camper into pedestal. Measure AC voltage from threaded F connector on camper to nut on F connector (shield) from end of cable that connects to camper. Even 1 AC volt is too much, there should be zero or very close to zero volts there. The electrician may not know enough about what is happening here.
LScamper 04/15/14 11:15am Technology Corner
RE: Coaxial TV cable getting hot / Need wiring diagram

With everything not connected measure the voltage from pedestal ground to cable shield connection. There has to be a voltage driving a current in the cable shield. Either a bad ground at the pedestal or on the cable. The park needs to be notified.
LScamper 04/14/14 10:58pm Technology Corner
RE: Proper Fusing Of Three Parallel Panels

Trying to make sense of panel fusing. A fuse is a current protection device. A fuse at the output of a panel is to protect the wires from the fuse to whatever it is connected to, mainly the controller. An array is the parallel connection of two or more panels (strings). A string is the series connection of two or more cells. A panel can be say 30 cells or 90 cells. A string can be one panel of say 90 cells or three panels of 30 cells in series, same exact thing! Say a panel is rated at 10A short circuit current and the fuses are 15A. So what happens if there is a short directly at a panel before the fuse? If there is only one panel the panel output goes to zero and the controller gets no input. The fuse will not blow, no current through it. If there are two panels in parallel and one shorts directly at a panel the output the voltage goes to zero and the controller gets no input. The short circuit current supplied by the other panel, 10A, now goes through both fuses, the one on the good panel and the one on the shorted panel. Neither fuse blows because they are rated to handle the current from one panel. The wires are safe because they are rated to handle at least the short circuit current from one panel. If there are three panels in parallel and one shorts directly at a panel the output voltage goes to zero and the controller gets no input. The short circuit current supplied by the other two panels is added, now 20A total, and flows through each of the good panel’s fuses, 10A each, and through the shorted panel fuse. This fuse now gets two times its normal current, 20A, and should blow from over current. When the fuse blows the voltage goes up at the controller and will still charge the battery from the two good panels. If the wire is rated to handle the current from the two good panels no fuse would be required. This would be the case in most of the installations talked about on the forum; most use much larger wire than needed to keep voltage drop at a minimum. This brings us to a reason not to use fuses at the panel, voltage drop! In order for a fuse to blow it has to dissipate some power to heat it to the melting point. This means that the fuse must have resistance. A 7A fuse resistance is about .013 Ohms and a 10A fuse resistance is about .008 Ohms. A 10-gauge wire has a resistance of about .001 Ohm per foot. So adding a 7A fuse is like adding about 13 feet of 10-gauge wire from the panel and a 10A fuse is like adding about 8 feet of 10-gauge wire. Plus there are all the connections that add resistance and could become loose or not a make good connection. Bottom line is if the wires from each panel can handle the total current from all the panels, most likely they can, there is no reason to use fuses and they introduce voltage drop plus added connections.
LScamper 04/10/14 02:51pm Tech Issues
RE: Water heater check valve question

I'm having the same problem. Mine is a brass valve and have not been able to break it loose. Waiting for warmer weather to work on it. May have to remove water heater to fix it. I can get a deep wall socket on it. Been thinking about trying an air impact wrench on it but don't know if that will damage the tank. Impact wrench may stress the tank less than using a big wrench. Anyone try that? What do you think?
LScamper 04/05/14 09:23am Tech Issues
RE: Exceptionally Good LED Power Tutorial

The reason for not using current limiting resistors to drive LEDs. Assume one 3.3V LED running off 12.5V at 20mA using a current limiting resistor. Voltage drop across the resistor, 12.5V – 3.3V = 9.2V. Resistor value, R=V/I, R= 9.2V/.02A, R = 460 Ohms. Power dissipated in LED, P=VI, P=3.3V*.02A, P=.066Watts. Power dissipated in resistor, P=VI, P=9.2V*.02A, P=.184Watts. Total power from power supply, P=VI, P=12.5V*.02A, P=.25 Watts. Efficiency = Pled/Pin, .066W/.25W, Efficiency = 26.4%! Not good. If voltage goes up to 14V then: Voltage drop across the resistor, 14V – 3.3V = 10.7V. Resistor value from last calculation, R = 460 Ohms. New current in LED and resistor, I=V/R, I=10.7V/460 Ohms, I=.023A. Power dissipated in LED, P=VI, P=3.3V*.023A, P=.076Watts. Power dissipated in resistor, P=VI, P=10.7V*.023A, P=.25Watts. Total power from power supply, P=VI, P=14V*.023A, P=.322 Watts. Efficiency = Pled/Pin, .076W/.322W, Efficiency = 23.6%! Not good. From this it can be seen that the LED current will go from .02A with a 12.5V source to .023A with a 14V source. A current increase of .003A or an increase of 15%. Not too bad. A current regulated power supply will hold the current to .02A and still have an efficiency of around 90%. Note it has to be a switching supply, a linear supply will be no more efficient. So what happens if you put several LEDs in series, lets say 3 LEDs. Total voltage across the 3 LED string, 3 * 3.3V = 9.9V. Voltage drop across the resistor, 12.5V – 9.9V = 2.6V. Resistor value, R=V/I, R= 2.6V/.02A, R = 130 Ohms. Power dissipated in LEDs, P=VI, P=9.9V*.02A, P=.198Watts. Power dissipated in resistor, P=VI, P=2.6V*.02A, P=.052Watts. Total power from power supply, P=VI, P=12.5V*.02A, P=.25 Watts. Efficiency = Pleds/Pin, .198W/.25W, Efficiency = 79.2%! Much better. If voltage goes up to 14V then: Voltage drop across the resistor, 14V – 9.9V = 4.1V. Resistor value from last calculation, R = 130 Ohms. New current in LEDs and resistor, I=V/R, I=4.1V/130 Ohms, I=.0315A. Power dissipated in LEDs, P=VI, P=9.9V*.0315A, P=.312Watts. Power dissipated in resistor, P=VI, P=4.1V*.0315A, P=.129Watts. Total power from power supply, P=VI, P=14V*.0315A, P=.441 Watts. Efficiency = Pled/Pin, .312W/.441W, Efficiency = 70.7%! Not as good as with 12.5V. From this it can be seen that the LED current will go from .02A with a 12.5V source to .0315A with a 14V source. A current increase of .0115A or an increase of 57.5%. Not very well regulated with using a resistor and may well destroy the LEDs A current regulated power supply will hold the current to .02A and still have an efficiency of around 90%. Note it has to be a switching supply, a linear supply will be no more efficient. If you look at a voltage from 10.5V, a dead battery to 14.8V when charging the current regulation with a resistor is really bad and most likely will cause a disaster. Hope I did not make a math error!
LScamper 03/26/14 04:09pm Tech Issues
RE: Not Balancing Three 12v Right

pianotuna wrote: “Balanced? *grin*” My post above was not meant as a joke, it was offered, free to use, as an alternative way to wire three batteries in a “balanced manner” as you like to say. I know that no two or three batteries are exactly the same but that is the assumption that is made every time someone on the forum talks about balanced manner. That is the assumption I will use here. As MEXICOWANDERER offered it is time to introduce Mr. Kirchhoff. His laws I became friends with almost 50 years ago. If someone takes the time to do the analysis it will be found that the star configuration and the parallel link configuration are electrically the same, no difference. The trick is to make the link from the + terminal of battery 1 to + terminal of battery 2 and the link from the – terminal of battery 2 to – terminal of battery 3 equal to on half the resistance of the other two links. This is done by putting two links in parallel. Do the analysis!
LScamper 03/19/14 10:04am Tech Issues
RE: Not Balancing Three 12v Right

There is more than one way to skin a cat for those that want to exactly balance the current in three batteries in parallel. The standard way is to use a star configuration with equal length links to each battery. This will exactly balance the current in the three batteries. There are other ways to balance three batteries also. Assume three matched batteries. Assume all interconnect links are the same length and gauge cable. Batteries are connected as usual: Load at opposite ends, + lead from + terminal of battery 1, - lead from – terminal of battery 3. Link 1 from + terminal of battery 1 to + terminal of battery 2. Link 2 from – terminal of battery 1 to – terminal of battery 2. Link 3 from + terminal of battery 2 to + terminal of battery 3. Link 4 from – terminal of battery 2 to – terminal of battery 3. Now to make it balance: Put another link from + terminal of battery 1 to + terminal of battery 2, making it two links in parallel from + terminal of battery 1 to + terminal of battery 2. Put another link from – terminal of battery 2 to – terminal of battery 3, making it two links in parallel from - terminal of battery 2 to – terminal of battery 3. Adding these two links will make the current in the three batteries exactly match and may be easier than making up a star configuration. There are other ways to do this by using different lengths of cable between the batteries but this is the easy way.
LScamper 03/17/14 02:40pm Tech Issues
RE: RV Plan 'N' Go 2013

It is junk, forget it! Maybe in a year or two they may get it to be usable.
LScamper 02/22/14 09:18am Technology Corner
RE: More Griping About Missing Standards LED lamps and lumens

GordonThree thanks. I guess that as long as all the LEDs are on a common heat sink so they are at the same temperature the forward voltage will track OK.
LScamper 02/21/14 10:16am Tech Issues
RE: More Griping About Missing Standards LED lamps and lumens

GordonThree wrote: "However, you could run six or nine leds, in parallel strips of three." LEDs need a current source as you have said. This controller is a current source. The LEDs need to be in series so all LEDs see the same current. If they are in parallel they would have to be matched exactly to share current, this won't happen. A parallel string is not a good idea in my opinion.
LScamper 02/21/14 09:06am Tech Issues
RE: Rechargeable Batteries

eneloop specs: clicky
LScamper 02/18/14 10:00am Technology Corner
RE: Frank's autotransformer question.

pianotuna wrote: "This will regulate both high and low incoming line voltage. I emailed Sola. The 60 va unit, which would be wonderful for a 30 amp RV, is about $411.00 plus shipping." Did you really mean 60 VA? That would be OK for a 60W bulb. I think you need the 5000 VA unit, at 222 lbs that would be a bit heavy to carry plus expensive.
LScamper 02/18/14 09:48am Tech Issues
RE: Rechargeable Batteries

clicky
LScamper 02/17/14 09:58am Technology Corner
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