I've made a custom set of lights for my brothers mantlepiece, since a commercial set I'd got him were too ferociously bright looking. So this set started off as a 100 lamp tungsten set of lights that I modified a capacitive dropper PSU for, and then swapped all the original tungsten lamps for nice fat diffused 10mm LEDs inserted in the correct polarity along the string.
To get the visual effect I required, I first upgraded the PSU (power supply unit) with new improved component ratings, and then initially put in a 100K resistor where the main dropper capacitor goes. The 100K resistor was partly experimental to see how much current it would pass, and partly so I could dab some different capacitors onto its exposed leads.
At this point I should mention that I was indeed dabbing components onto live electrical connections at full mains voltage (240V). I wouldn't really recommend this sort of practice unless you know exactly the routes to ground that electrical current could take.
So here are the results:-
100K resistor alone = 0.5mA LED current.
100K bridged with 22nF = 0.75mA
100K bridged with 47nF = 1.25mA
100K bridged with 100nF = 2.6mA
100K bridged with 220nF = 5.6mA
100K bridged with 330nF = 8mA
I chose the 100nF capacitor in the end and the lights look great.
Power consumption of the whole string is around half a watt, giving a running cost of just 50 cents/pence a year for continuous 24/7 operation.
One of the most surprising results was that the 100K resistor alone passed enough current to make the LEDs glow at a very nice intensity. The power dissipation across the resistor was an incredibly low 0.025W which is one tenth the resistors power rating.
With the 0.5mA current the lights would have operated at 1/10th of a watt and cost just 10 cents/pence a year to run 24/7. That's for the whole string of 100 lights!
To get the visual effect I required, I first upgraded the PSU (power supply unit) with new improved component ratings, and then initially put in a 100K resistor where the main dropper capacitor goes. The 100K resistor was partly experimental to see how much current it would pass, and partly so I could dab some different capacitors onto its exposed leads.
At this point I should mention that I was indeed dabbing components onto live electrical connections at full mains voltage (240V). I wouldn't really recommend this sort of practice unless you know exactly the routes to ground that electrical current could take.
So here are the results:-
100K resistor alone = 0.5mA LED current.
100K bridged with 22nF = 0.75mA
100K bridged with 47nF = 1.25mA
100K bridged with 100nF = 2.6mA
100K bridged with 220nF = 5.6mA
100K bridged with 330nF = 8mA
I chose the 100nF capacitor in the end and the lights look great.
Power consumption of the whole string is around half a watt, giving a running cost of just 50 cents/pence a year for continuous 24/7 operation.
One of the most surprising results was that the 100K resistor alone passed enough current to make the LEDs glow at a very nice intensity. The power dissipation across the resistor was an incredibly low 0.025W which is one tenth the resistors power rating.
With the 0.5mA current the lights would have operated at 1/10th of a watt and cost just 10 cents/pence a year to run 24/7. That's for the whole string of 100 lights!
Hi Clive, where was the 100 LED set purchased? Thanks.
I used CC driver from old 11W E27 led bulb to power this string at 5mA. I had to change CS resistor to about 20 Ohm.
Big Clive did you remove then100k resistor when you put the capacitor onto the on or was the capacitor put next to the resistor and which pay did you use
hi could you add a link to where you got the capacitor
dropper from
I'm missing the notepad.
The final circuit would be nice Clive.
How do you tell what LEDs you have? The voltage drop is different for each colour isn't it, so how do you find if they're nitride or arsenide? Thanks Clive
Clive dabbing before it was popular
the lights look tasty like candy
It's a pity no manufacturer seems interested in putting more than 4 colours in their LED fairy lights, whereas the traditional colour fairly light bulb sets had 5 or 6 colours. Instead, they seem to be competing on brightness and flashing effects. Some sets in the shops appeared so bright even in the store's bright lighting that it made me wonder how could anyone watch TV with a Christmas tree lit up with them!
That custom set indeed reminds me of the previous 6 colour bulb set we had but with pink instead of orange. In the end we could no longer get replacement screw-in bulbs, so ended up having to scrap them.