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 > Your search for posts made by 'LScamper' found 36 matches.

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RE: Circuit simulation software

"pspice is another good alternative. interfaces nicely to orcad and cadence design layout tools." The free version has limitations but I don't know what they are. Do you? LTspice is the full unlimited version.
LScamper 11/20/15 05:34pm Tech Issues
Circuit simulation software

Spice circuit simulation software has been mentioned here several times. When I was in the business I used a circuit simulation program to test designs before they were prototyped. The versions of Spice that I used cost $5,000.00 > $10,000.00 plus about $1000.00 per year maintenance. Today you can download a free version that does the same thing and is free. It is called LTspice. The main difference is that the expensive ones come with more components in the package but you can add them to the free one with a little work. The video in the link below is a little old but should show you how to get the program and start using it. LTspice download
LScamper 11/20/15 03:31pm Tech Issues
Heatsink design 101

Some of you are designing LED lighting and need to use heatsinks. These videos may help in doing the job correctly. Thermal Design 101 Thermal design sucks
LScamper 11/20/15 11:42am Tech Issues
Kirchhoff's circuit analysis for the curious

Kirchhoff is often mentioned on this forum. These two videos explain Kirchhoff. This may be interesting to some that want to understand more about their 12V DC circuits. It is very advanced for the beginner and uses some math. Kirchhoff's law 1st video Kirchhoff's law 2nd video
LScamper 11/20/15 09:05am Tech Issues
RE: Super Cap USB Charging Recharging (?)

Here's the deal. My cell phone battery is rated at 2,800 mAh (2.8 Ah) at 3.85 V. Watt-hours equal Amp-hours x Volts, 2.8 x 3.85 = 10.78 Wh. To convert Watt-hours to Watt-seconds multiply by 3600. So 10.78 Wh = 38,808 Watt seconds, the total amount of energy stored in this fully charged battery. One Watt-second = one Joule. A Joule is the measure of energy. So the total energy stored in this battery is 38,808 Joules. Now for the 16 farad capacitor. Total energy stored in a capacitor is total Joules = (Volts x Volts x capacitance)/2. Total Joules = (5.5V x 5.5V x 16 farads)/2, total Joules = 242 Joules stored in this 16 farad capacitor. So the battery stores 38,808 Joules and the capacitor stores 242 Joules. Divide 38,808 Joules by 242 Joules and get 160.36. Bottom line is that the battery stores 160.36 times more energy than the 16 farad capacitor! Of note is that you will not be able to transfer all the 242 Joules from the capacitor to the battery.
LScamper 09/21/15 02:19pm Technology Corner
RE: Parallel then series, or the other way around?

"You didn't doubt Kirchhoff, did ya?" Kirchhoff is never wrong, but at my age my math is!
LScamper 08/24/15 08:45am Tech Issues
RE: Parallel then series, or the other way around?

Spice circuit simulation confirming Salvo's calculations. 105 Amp constant current load. Also tried to simulate Amp hours and state of charge vs time. The vertical scale should be Amp, Amp hours and percent state of charge not volts as is shown. The horizontal axis is in seconds. 3600 seconds is one hour. The colors may not show up very well, but I tried. Amps http://i.imgur.com/a2w5EKRl.jpg "border=0" http://bit.ly/1CIRlV8 Amp hours http://i.imgur.com/HkUrZOLl.jpg "border=0" http://bit.ly/1CIRlV8 State of Charge http://i.imgur.com/QycQ3Vul.jpg "border=0" http://bit.ly/1CIRlV8
LScamper 08/23/15 05:21pm Tech Issues
RE: Parallel then series, or the other way around?

"And here come the experts In some ways Norton’s Theorem can be thought of as the opposite to “Thevenins Theorem”, in that Thevenin reduces his circuit down to a single resistance in series with a single voltage. Norton on the other hand reduces his circuit down to a single resistance in parallel with a constant current source." Exactly!! Nitpicking that's all. n7bsn wrote: "Please explain your theory using Norton's Theorem" Norton and Thevenin both create a black box with the equivalent circuit in it. You can't tell what is happening inside the box from outside measurements.
LScamper 08/22/15 03:40pm Tech Issues
RE: Parallel then series, or the other way around?

hotpepperkid wrote: "Good luck with that. Doesn't Norton's Theorem just simplify any circuit containing resistance and a voltage source to an equivalent circuit" Not correct
LScamper 08/22/15 02:51pm Tech Issues
RE: 100% Of The Capacitors Turn-Around In My Old WhiffCo.

MEXICOWOANDERER wrote: " I have a 330uf 450vac axial cap ready to install across the output." I'm not sure I understand. Are you planning to connect the 330uf cap on the output from hot to neutral? If so why, seems like a bad idea.
LScamper 08/19/15 10:29am Tech Issues
A look inside 80W ceiling LED

This may be interesting to those playing around with high power LED lights. 80W LED teardown. Teardown Video
LScamper 07/30/15 08:59am Tech Issues
RE: PWM input voltage, Xantrex C40 test video

red31 wrote: "PWM or 16.62-13.92 * 16.10a = 43.47 Watts going to heat up controller? "16.62 controller out 13.92v" Think about 43.47 Watts going to heat up controller. If you have a series PWM controller and it is in the off state the panel voltage is at V open circuit as you have said. But in the off state the current is zero! With zero current there is no power dissipation (P = V*I) to heat the controller. Also if you have a shunt type PWM controller and if is in the off state the panel voltage is zero, the panel output is shorted by the controller. With zero voltage there is no power dissipation (P=V*I) to heat the controller. OK there will be a small voltage drop across the shunt switch so there will be a small amount of power dissipation with a shunt controller.
LScamper 07/27/15 08:19am Tech Issues
RE: PWM input voltage, Xantrex C40 test video

Looking at the schematic and believing MrWizard's reading this is what must be happening. Even when the controller should be on all the time, max charging, it is not. There must be a small time that the controller is off and the panel voltage is at V open circuit, the volt meter is averaging the voltage to get what MrWizard is seeing. This is not an uncommon situation with PWM. There really is no way to know really what the voltages are without using a scope and each brand controller could be quite different and still be called PWM. Here is another question that I don't think has been asked. If the controller is pulse width modulating the panel voltage it also must be pulse width modulating the current to the battery. So the current that is being read as charge current is an average current, not a constant DC current. MrWizard wrote: "if you have a DC power supply with a voltage at a set voltage powering equipment that voltage will not change unless the load exceeds the ability of the power supply" TRUE "the panels are a pure DC power supply the controller is the voltage regulator" FALSE -- the panels are current sources.
LScamper 07/25/15 05:13pm Tech Issues
RE: One 50Mv 500A shunt, two ammeters?

500A, 50mV shunt will have a resistance of .0001 Ohms. If you put a 1 Ohm resistor across that shunt the voltage would only change by .01%. Putting 2 meters across it will not change the current reading enough to see on any meter.
LScamper 07/25/15 09:31am Tech Issues

TireMinder Manual Some info on TireMinder. I think most pressure monitors work about the same way. The monitor does not read the tire pressure all the time. Each wheel transmitter send information to the monitor at some update time. TireMinder is about 20 min.(?) between sending information. The updates from each wheel are random. If they were updating all the time the batteries would not last long. The monitor keeps track of the updates. If for some reason it does not get an update it will wait for 2 or 3 cycles before it notifies you of a lost signal. This reduces false warnings. It also means that you will not know that you lost signal for that time. Seems like all brands do the same thing. If there is a sudden change in tire pressure the monitor will send information as soon as that happens. If I remove a transmitter I will get a tire lost pressure warning at that time. It does not wait for the 20 min update time if that happens.
LScamper 07/17/15 08:55am Tech Issues
RE: Maxxis Load D To E - Bouncy Ride

Maxxis tire chart: clicky Ran Maxxis ST205/75R15 at 50 lbs (1820 lbs per tire) for many years. Had several tread separations but just replaced with the same type tire. Gave up on Maxxis and tried Green Ball from Direct Tire. After about one year one of them blew out and another had a large bubble. I'm sure my trailer is over weight but have not measured it. Called Maxxis engineer to talk about updating tires. He suggested going to ST225/75R15 at 55 lbs (2270lbs per tire), a 25% increase in capacity and should ride about the same. Could go to 65 lbs (2540 lbs per tire) if I want to. Had to make sure there was enough clearance for the 1.2 inch diameter larger tire and get new rims. Have not towed enough to see if these tires are more reliable. I asked about truck tires. The only thing he said was that after all the problems with car tires several years ago that they now have a much larger built in safety factor than they had back then.
LScamper 07/04/15 06:31pm Travel Trailers
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