Resistor to trick 12v transformer

Click For Summary

Discussion Overview

The discussion revolves around the challenge of using LED lights with a 12-volt transformer that appears to require a certain load to function properly. Participants explore potential solutions for tricking the transformer into recognizing a higher load, including the use of resistors or other devices. The conversation includes technical details about the transformer and LED specifications, as well as the implications of using incandescent bulbs alongside LEDs.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant asks how to trick a 12-volt transformer into seeing more load to power LED lights that do not function without an incandescent bulb present.
  • Another suggests looking into motorcycle accessory catalogs for load-adding gadgets that could be applicable.
  • There is a question about the required ohms and amps for the load.
  • Some participants express confusion about whether the LED modules are rated for AC or DC voltage.
  • One participant notes that the transformer outputs low voltage readings when unloaded and higher voltage with an incandescent bulb, suggesting a need for more load.
  • Another participant mentions that electronic transformers may require sufficient load resistance to operate correctly.
  • Discussion includes the possibility of the transformer being a switching mode power supply rather than a conventional transformer.
  • Some participants propose using resistors as a potential solution to maintain load without using incandescent bulbs.
  • There is mention of the transformer being dimmable and questions about its compatibility with dimming controls.
  • One participant suggests that the transformer may not be functioning correctly if it outputs low voltage readings under certain conditions.

Areas of Agreement / Disagreement

Participants express a range of views on how to address the issue, with no clear consensus on the best approach. Some agree that additional load is necessary, while others question the nature of the transformer and its requirements. The discussion remains unresolved regarding the optimal solution.

Contextual Notes

Participants note the lack of specifications for the LED lights and the potential limitations of measuring equipment, which may affect the understanding of the transformer's output characteristics. There is also uncertainty regarding the exact nature of the transformer and its operational requirements.

  • #31
Hi
I have an excellent test-equipment design I want to share with you because it will enable you to track down your fault.
It needs parts : 2 of 12v filament lamps; a mounting arrangement for the lamps, and a probe. Oh, and red and blue paint.

Connect the 2 lamps in series, and connect the series circuit to the battery which is supplying the circuit under test. Connect the probe to the joining between the 2 lamps.
The 2 lamps glow weakly as soon as they are connected. If the probe is touched to a part of the circuit at positive voltage, one of the lamps will glow. Paint this one red. Paint the other lamp blue.
Keep this test equipment forever! You will soon find faults like the one described in this thread using your 2-lamp tester!
 

Attachments

  • untitled.PNG
    untitled.PNG
    739 bytes · Views: 434
Engineering news on Phys.org
  • #32
Could it be that the leds are self-biasing themselves off in some way as charge is only flowing one way through the circuit? Foggy thinking on my part, here, but I seem to remember something of the sort happening in another context.
You could try connecting one of the led units the other way round which would stop this happening as current could then flow in both directions through the transformer.
If it works then I was right - otherwise I wasn't!
 
  • #33
Besides the fact that it is an "electronic transformer" (i.e. ballast), it also states:
Soft Start
Overload
Short Circuit Protection
Auto Reset
For 12V Halogen Lights Use Only

Correctly-biased LED's probably look like a short circuit to this device, therefore causing it to shut itself down.