Led bulb lights then blows

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RL19

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This is really puzzling me.

I have a cold plunge barrel which has a waterproof light in the bottom

It is a low power LED set up with a constant current transformer from the mains powering a single LED bulb. See pics.

Decided to put an outdoor switch between the transformer and the lamp to make it easier to switch on and off.

Now when you operate the switch the light bulb blows. Can’t work out why. Have checked current to lamp and all fine per transformer spec and don’t see why putting a switch in would change that?

Any ideas ?
 

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Yes.

Put the switch on the input to the driver, in the 240v line.

What I suspect is happening is the output voltage is rising to provide the constant current that its configured to achieve 350ma, because the switch is open, there is no load and no current flow so the output voltage ramps up to the 36v. When switch on the ouput voltage from the charged capacitors of 36v with a bit current behind it will blow the LED.

If youre unhappy about switching the 240v, you could put a couple of resistors in series with the LED to take some of the surge out. 30 ohm, 5w resistor should do it and it wont reduce the brightness of the LED.

https://www.ebay.co.uk/itm/12223311...CjeC7sVvevF+FWbkwswXxRvB/cnr|tkp:BFBMlp6Ns8Ri
 
Last edited:
Yes.

Put the switch on the input to the driver, in the 240v line.

What I suspect is happening is the output voltage is rising to provide the constant current that its configured to achieve 350ma, because the switch is open, there is no load and no current flow so the output voltage ramps up to the 36v. When switch on the ouput voltage from the charged capacitors of 36v with a bit current behind it will blow the LED.

If youre unhappy about switching the 240v, you could put a couple of resistors in series with the LED to take some of the surge out. 30 ohm, 5w resistor should do it and it wont reduce the brightness of the LED.

https://www.ebay.co.uk/itm/122233114761?hash=item1c75a95089:g:YY0AAOSwvFZW8Bsf&amdata=enc:AQAIAAAA4NeCKk5bi0ELgS+l3dmXXkcjSd+dziTn7KyeOHSEJmtDlUGMeCIL9/pInfP3AOgHfE2DZgzmcgU7FfiRwjlJ6Il3gbXtZLaMtbXheXAU0SpDXNwyRc2MxzFik398LwgV9TIp9aCEps0DicSYGnuzncu5rnTRkKDPsu6g16Jui3tZ2/blVdax/I6qVWbfFM5Fs9n+WW2A8sZMQfIBcMrlI/mLVV0PeR2TM8CvK54UGCVWfL0t0B7IEEBl6iBMgL90b6/um33fsnMoryrBCjeC7sVvevF+FWbkwswXxRvB/cnr|tkp:BFBMlp6Ns8Ri
Thank you very much i hadn’t thought of that but does make sense
 
You alternatively use the switch to short circuit the led, the driver will be fine, it will just output 350mA at very low voltage and nothing nasty will happen.
I’m not sure that won’t just confuse RL19, John your first sugestion of switching the input was perfect.
 
Thanks guys useful suggestions. Just waiting on a new bulb then will try with the switch before the transformer to start off with. If that doesn’t work will go with the remote option. Thought this was going to be a simple switch install!
 
Yes.

Put the switch on the input to the driver, in the 240v line.

What I suspect is happening is the output voltage is rising to provide the constant current that its configured to achieve 350ma, because the switch is open, there is no load and no current flow so the output voltage ramps up to the 36v. When switch on the ouput voltage from the charged capacitors of 36v with a bit current behind it will blow the LED.

If youre unhappy about switching the 240v, you could put a couple of resistors in series with the LED to take some of the surge out. 30 ohm, 5w resistor should do it and it wont reduce the brightness of the LED.

https://www.ebay.co.uk/itm/122233114761?hash=item1c75a95089:g:YY0AAOSwvFZW8Bsf&amdata=enc:AQAIAAAA4NeCKk5bi0ELgS+l3dmXXkcjSd+dziTn7KyeOHSEJmtDlUGMeCIL9/pInfP3AOgHfE2DZgzmcgU7FfiRwjlJ6Il3gbXtZLaMtbXheXAU0SpDXNwyRc2MxzFik398LwgV9TIp9aCEps0DicSYGnuzncu5rnTRkKDPsu6g16Jui3tZ2/blVdax/I6qVWbfFM5Fs9n+WW2A8sZMQfIBcMrlI/mLVV0PeR2TM8CvK54UGCVWfL0t0B7IEEBl6iBMgL90b6/um33fsnMoryrBCjeC7sVvevF+FWbkwswXxRvB/cnr|tkp:BFBMlp6Ns8Ri
Hi John Just to come back on this as there has been a delay whilst I ordered a new bulb (@£25 a go!). Your solution worked in moving the switch ahead of the transformer. Thank you very much for your help as I would not have worked that out myself and would have spent a fortune on bulbs trying to fix it!!
 
Hi John Just to come back on this as there has been a delay whilst I ordered a new bulb (@£25 a go!). Your solution worked in moving the switch ahead of the transformer. Thank you very much for your help as I would not have worked that out myself and would have spent a fortune on bulbs trying to fix it!!
No problem at all, I'm glad the remote diagnosis was right ! Thank you for updating us too, many people dont and it is nice to hear if solutions have worked.

Enjoy plunging!
 
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