| Author | Message | ||
| R.C. Bishop
Rating: N/A |
Just purchased a couple of strings of exterior/interior commericial lights (mucho pricey, whew!!!) which are 120 ac wired, but appear to have a transformer built into the supply line just before the plug. Question: Can the transformer be completely eliminated and the connection (prior to the transformer) be directly to 12 volt DC? (Switched also) Thanx for the help.  RCB | ||
| WEC4104 Rating: N/A |
RC: Of course it is tough to answer your question without make or model info, or a looksee at what you have. However, there is a good chance 12 VDC is what you have. Throw a volt meter on it? I know I installed some 12 VDC rope lights in my 4104 3-4 years ago. I did not want the glitsy Prevost look so the light rope was hidden from direct view. I just wanted some indirect low level lighting that would let passengers get around at night without distracting me why driving. I was very pleased with the result, at least until sections of the rope started to "burn out". Of the 12 feet of total length installed, I eventually ended up with 4 or 5 sections about a foot long that were dead. I eventually ripped it out and eventually built a replacement using a metal strip with a white LED spaced every 4". That solution has been rock solid for me. Low current draw too. In retrospect, I think I liked the white rope light's warmer color better. The white LEDs are more bluelish-white and look more like moonlight. Sometimes I wonder if I would have preferred yellow LEDs instead. Hope your pricey commercial units hold up better than mine did. WEC4104 | ||
| Crane Rating: N/A |
Look at the power supply. I assume it is a wall plug in simular to a power supply for a calculator or such. Look at the voltage. probably reads 12vdc but could say 24v dc. If your string of lights is incandescent, that is is has a filiment like a normal bulb, AND if the transformer says 12vac or 12vdc, you can use a fuse and plug the bus 12vdc into the string. You can also use a fuse and plug into the string if the power supply is 24v, the lights will be dimmer, a bit less than half brilliance. This would also give a nice effect and the bulbs may last longer. If the string is of LEDs, then only DC can be applied and you have to attache to the polarities correctly or you can burn out the leds. If the string is LED and they require 24vdc, they may still work at 12vdc, again, brilliance less, but this is something you would have to try. Connection configurations are so variable by the manufacturers these days that possibility of working due to resistors and such is 50/50 at a different voltage than supplied by the power supply. I think there are other alternatives out there too. I don't recall where but there was a place that was selling a string of LEDs. don't recall the color but was lo voltage. Look around and look at the hobby places. All Electronics might have some thing too. i think there was a link where the 5" led monitor was mentioned before. Good luck Crane | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
I would suspect that the power supply is marked 12 volts AC instead of DC. However, it should not make any difference. They should work on DC as well as AC. Richard | ||
| Rob King
Rating: N/A |
Hi RC If you need a source of 12 volt led rope light, this maybe the ticket: http://www.sailorsams.com/led-rope-lights.htm It has been my experience that most transformers with these rope light kits are output of 12 volt DC but as others have mentioned, maybe 12 volt/24 volt(less common)ac or others. If the wires to the rope light are detachable from the transformer, in some case, you can detach them and using a voltmeter, measure the output. Hope this helps Rob 91 LeMirage XL Missouri | ||
| R.C.Bishop
Rating: N/A |
Thanx for the input, guys...under the circumstances, I think I'll stick with the 120 volt setup that is made up in the string. The manufacturer told me it would " void the warranty"....among other things. "preciate it, tho! RCB '64 Crown Supercoach (HWC) | ||
| Stephen Fessenden (Sffess)
Rating: N/A |
LEDs work on AC or DC. On DC the polarity has to be right, on AC they act as diodes to use half the cycle, that is they are self rectifying. The worry would be that there is a resistor balast built in to the power supply. LEDs need a ballast resistor. | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Um Stephen, bad info. I'm surprised... Leds do not work (reliably) on AC as you've described... Yes LEDs are diodes but, and it's a big but, they don't like being reverse biased..ie they will usually die if hooked to AC because their "PRV" (peak reverse voltage) withstand rating is horribly low as compared to an average rectifier diode. Usually no more than a volt or two higher than their forward drop, if even that much... Typically, as you said, an LED will need a ballast resistor to control the current going through it. That means the power supply, whatever it is, has a much higher voltage than the forward (or reverse) voltage of the LED. Using AC as you've describd, when the cycle is reversed in polarity, the LEDs don't draw current. The voltage across them goes from their forward-drop value to the full value of the power supply as the polarity reverses, which is quite often a voltage much above their PRV value. Then they die. LED's are often used on AC circuits, but to do so they are usually hooked in anti-parallell pairs, such as in these circuits... http://www.discovercircuits.com/PDF-FILES/NewPDF/acwhiteleds.pdf This way, because one LED of a pair "protects" the other, neither LED is ever subjected to a voltage greater than it's forward voltage, and it will survive just fine. It's possible that a variation of one of these circuits is what is in RC's strings... | ||
| Stephen Fessenden (Sffess)
Rating: N/A |
Sorry about the bad info. It came from a supposedly reliable source. It is easy enough to put a diode in the circuit anyway.s | ||
| R.C.Bishop
Rating: N/A |
Follow up.....I ended up plugging into a 120 outlet, one on each side of the coach "hidden" in cabinets..... that outlet switched at convenient locations on each side. A bit of a pain, but in the end, probably a better solution because I added an additional outlet on the end of both cabinets. KISS, right? Thanx for the input fellow busnuts. RCB '64 Crown Supercoach (HWC) |