Can't Switch Light Off

As suggested put an incandescent lamp anywhere in parallel with the led lights and see what the results are.
 
Thank you all.

Tim, the incandescent lamp works but it is not appropriate to use in the final arrangement. (see also reply Posted: Sat Aug 25, 2007 6:40 pm)

Breezer,

Your suggestion is essentially what we have done in study i - albeit with only one led.

Our next study will be to take the i study and recreate it in another house

After that I will invite the supplier to either come and fix or make up study i in their workshop - This could be a problem for all of these lights.
 
Can anyone guess why a shorter wire might work? I'm not sure its induced current as the intensity is the same irrespective of if the long switchwire is coiled or spread out. I even tried one with a decoupled switchwire (ie two separate wires).

If it was induction, can I purchase a 240V shielded cable for the switchwires?
 
have you ever thought it may be the lights are just S***

i have some led lights (not ones i made) they do glow for a few seconds after being switched off
 
Another thought... A suitably rated relay to switch the LEDs... Use the existing switch circuit to energise the coil of the relay mounted close to the LEDs. That would keep the amount of wiring 'downstream' of the 'switch' to a minimum to reduce any capacitive coupling.

Or different LED arrays powered from one low voltage DC power supply.

Induction is a magnetic effect that requires a current flowing in the 'driving' conductor to induce a voltage in the 'driven' conductor

Capacitive coupling only requires a voltage to be present in the driving conductor.

Only 'problem' with using a relay is the relay may well draw more current than the LEDs it is controlling :?
 
TicklyT said:
Another thought... A suitably rated relay to switch the LEDs... Use the existing switch circuit to energise the coil of the relay mounted close to the LEDs.
Click to expand...

Yes this does work. but it has to be a relay with mechanical contacts and not a solid state one.

But putting the relay coil across the LED's will also drain away most if not all of the capacitively coupled charge as the incandescent bulb does.

A correctly sized snubber (resistor and capacitor in series ) across the LEDs will also solve the problem
 
What kind of cable is the switchdrop?

In the UK we use a ble called twin and earth, its a flat cable and the earth is in the middle, this helps reduce the capacitive coupling between the two current carrying conductors, something in the back of my mind tells me that one country uses a similar cable with Earth to one side, but cant remember where!
 
Thanks again all.

Adam_151, the standard switching cable is 2 core 1mm² wires insulated in red and black respectively with both insulated with a white sheath.

I did try using standard power cable for the switching wire (running 1,2 to 1,2 in the diagram) and in Australia this has an earth as the middle core of 3 cores. Had the same problem.

The short cable which was not a problem was standard light switching cable.
 
Could someone please tell me how to size a snubber for this arrangment. We have now tried a 5W 10ohm ceramic resistor. When placed in parallell with one of the LEDs I still get the dim glow.

I expect that there is a solution here as the 60W incandescent worked and I guess that the ceramic resistor is essentially the same thing (except it doesn't glow or get as hot when the lights are on). I can keep increasing the wattage on the ceramic resistors but if a capacitor is required too, there are a few too many variables for me to sift through without much experience in this area:

1. ceramic resistor wattage
2. ceramic resistor ohms
3. capacitor specification (and why do I need it)

Can anyone please :( even take a stab at 1 to 3 so I can put this one to bed.
 
You could try a 0.1 microFarad capacitor in series with a 100 ohm 1/2 watt resistor across the mains supply feeding the lights.

Capacitor must be rated at 250 volts AC or higher, metalised polyester type would be suitable.

This combination is available pre-packaged and sold as an arc suppressor for contactors.

for example RS Components Stock Code 616 7682
www.rsaustralia.com
 
Wouldn't that be approx 500watts added load to the unit which I believe was rated at 1.2w?
 
tim west said:
Wouldn't that be approx 500watts added load to the unit which I believe was rated at 1.2w?
Click to expand...

If the capacitor wasn't there then the 100 ohm resisistor would be a 500 watt very short lived load. The capacitor has a high impedance at 50 Hz so the resistor carries very little current

An it goes on the 240volt mains input to the unit and not on the unit's output.
 
Sorry i misread your post and thought you said put it across the output as I would assume one would do if trying to load the circuit, can't quite see how putting it across the supply would achieve anything though?
 
tim west said:
Sorry i misread your post and thought you said put it across the output as I would assume one would do if trying to load the circuit, can't quite see how putting it across the supply would achieve anything though?
Click to expand...


The dim light is caused by the capacity in the switch wiring between LIVE and Switched Live which is in parallel with the switch and when the switch is off allows small amout of power to reach the lamps.

Every time the AC changes polarity the 0.1 uF capacitor absorbs this small amount of capacitively coupled power and thus prevents it being used by the lamps.
 
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