Capacitive voltage dropper for LED pilot lights -- test

This test was done for Electrotech Forum where a LED circuit with capacitive voltage dropper was discussed.

It shows the importance of having correctly rated mains Capacitors (X2 rated) or at least twice the peak rating of the mains voltage (1 kV in this case)

Mains Voltage used was 240 Volts 50 Hz

Initially three LED's were subjected to a test.

LED-1 was connected to four 47nF 1kV rated caps ( in parrallel ) 188nF
LED-2 was connected to a 0.1uF 300V rms rated capacitor
LED-3 was connected via a resistive voltage divider consisting of two 27 k.ohm 1 Watt resistors.
All LED's have a 1N4448 blocking diode in parrallel with the led.
Also a current limit R of 680 ohm or 1 k.ohm ( 1 W ) was used to reduce inrush current destroying the led.
Parrallel cap discharge R's were fitted too 270 k.ohm or higher.

Before I had my camera ready the first Cap had exploded at 92 events. I did not expect that cap to fail so early in the test.

LED-2 was replaced with similar LED and same type capacitor. That one failed within about 200 minutes, the cap shorted internally and remained intact but the series R burnt out, LED and diode failed.

LED-4 was added later with a X2 rated 275 V rms cap of 0.1 uF. that worked fine.

Current measurements are shown of the circuits in use.

The timing intervals were 57 seconds on 3 seconds off every minute.

The survey was done over 17000 events

I created this video with the YouTube Video Editor (http://www.youtube.com/editor)

Category:

Science & Technology

Tags:

• LED
• capacitor
• survey
• test
• durability
• Kondensator
• capacitive
• capacitance
• resistor
• Hengstler
• counter
• mA
• meter
• 240Volts
• pilot
• light
• event
• faillure
• YouTube editor

[cristian3131]

call me newbie, but what is ALL that for ? What does it do ? AMAZING !

[RODALCO2007]

@cristian3131 It drops the voltage to a low level with almost no power loss.

[7ReyZor]

Are MCBs just circuit breakers? I live in the US, and we just call em circuit breakers.

Also, what is this for? Is there any sort of advantage to a capacitive voltage dropper versus a resistive one?

Very interesting stuff.

[RODALCO2007]

@7ReyZor Yes, it stands for Miniature Circuit Breaker.

This topic was discussed in an electrical forum. I prefer the resistive method which is very reliable. some people prefer the capacitive method which doesn't waste any power but is more prone to faillure because of voltage spikes.

[locouk]

You exchanged the kids for cats this week I see :D

[RODALCO2007]

@locouk Yes, at least they purr and are not as noisy.

Next time i feed my kids ice cream when doing a burn out video

LOL !

[MrRootbrian]

Wish I could see the capacitor popping and zapping the LED's lol

[RODALCO2007]

@blackmesa25 electric clocks and relays

[911Ravager911]

@RODALCO2007

I see that cats are the prefered pet of electricians. Got also one. LOL!

[CassetteMaster]

This is simply amazing.

[MrGerbilBrain]

hmm, well the peak voltage of 240VAC is almost 300V, so no wonder the capacitor failed. I used a small 250V .1uF film capacitor which is ok for 120V. LOL lazy cats xD

[douro20]

Interesting that the Germans really don't have a name for Wednesday...they just call it mid-week...