110V bulbs on Festoon Lighting

[Forestlands]

Hi Folks, thanks for all your great replies - loved the reminiscing!

I'm using a heavy duty Faithful Power Plus 16 amp 3.3KVA transformer, I'm sure you will be familial with them. Have 10 bulbs on the festoon lighting. Have a farm and got the lights up in an old piggery I use in the evening. Son suggested I got them, they are used at his work, he won't have anything to do with electric says it's not safe! He works on gas leaks! ROFL!

Reading your reply's looks like there is unlikely to be a problem,will try them out, will be able to keep an eye while working. Will let you know tomorrow!

I'm very grateful to you all for taking the time to post replied. You are experts, skilled in electrics, I appreciate being able to ask your advice! Thank you very much!

 

[SimonH2]

There is typically an inductor in a switching regulator/power supply. In a buck (step down) converter the (simplified) description is that the inductor is between the supply switch and the load - with a free-wheeling diode between return and the supply side of the inductor.
Switch turns on, current in inductor rises (V=L di/dt) or re-arranging it, di/dt = V/L where V is the voltage across the inductor (input DC voltage - LED forward voltage), L is the inductance of the inductor, and di/dt is the rate of change of current.
At some point, the switch is turned off, and the inductor current tries to go to zero instantly. As anyone who was awake during school physics lessons knows, inductors don't care much for that - plug "very large rate of change of current (di/dt)" into the above equation and you'd get "very large voltage", something that's good for a car ignition coil but not good for these applications. What happens is that the input side of the inductor will try to go negative (I'm assuming the switch and inductor in the positive), and it will do so until the flyback diode conducts - at which point V is effectively capped to a constant (LED forward voltage - diode forward voltage drop) - and so the inductor current ramps down.
The LED current will be a repeating series of up and down ramps. There are many ways of operating the switch - fixed frequency and vary the mark-space ratio, fixed on period and vary the off period, fixed off period and vary the on period, and the "relaxation regulator" method where you simply switch the switch on when the current drops below the setpoint and off when the current is above it (with some hysteresis).

As an aside, many (most) of the non-dimmable LED bulbs are simply a bridge rectifier and a resistor - with the LED strings setup to run at a high voltage. These have annoying 100hz flicker.
The coloured 2W bulbs I got for our outdoor lighting (mentioned in another thread as they turned out to not be weather resistant !) have a capacitor and inductor (I think, labelled "RX on the board, may be a resistor) in series as the voltage dropping components - then a bridge rectifier, a smoothing cap, then a resistor, and then the LED strings. While they say non-dimmable, they actually dim very nicely on a variac, and I ran them at 55V off a transformer which made them a nice brightness.

 

[JohnW2]

As an aside, many (most) of the non-dimmable LED bulbs are simply a bridge rectifier and a resistor - with the LED strings setup to run at a high voltage.

(assuming we are talking of 'mains' ones, and not 'LED tubes') ... That may be true of ones with relatively long strings of LED elements (i.e. many LED elements in series), but nearly all those I have taken apart have had just a small handful of LED elements (sometimes only one), in which case the large VD across the resistor would be very high. Since that would result in very poor efficiency (and appreciable heat production), those I have taken apart (particularly 'cheap' ones) have almost always had a bridge rectifier and a capacitor, rather than resistor.

Kind Regards, John

 

[Forestlands]

Thank you all, very much, for your replies. Just to let you know lights working fine! LED give off much better light, only 7w whereas energy saving bulbs are 20w and getting dim! Kind regards

 

[EFLImpudence]

In your situation, the LED lights are the energy saving ones.

I would complain to the manufacturers of the 20W lamps and tell them they are wrong and the "energy saving" description is meaningless nonsense.

 

[Forestlands]

Hi folks reporting on the bulbs mentioned, the so called energy saving bulbs, made by Kosnic. Careful when buying as Kosnics idea of energy saving bulbs my differ from yours! I wouldn't call 20W energy saving, check out the numbers before the words. Thanks again for you great replies, have a lovely weekend!

 

[ericmark]

Energy saving to my mind is reducing the energy which escapes from the home. Double glazing, cavity wall insulation, insulated floors, insulated roof, and heat recovery units all help it reducing the energy which escapes, only when the home is naturally going to be above 17°C is there any saving by using items that produce less heat, up to that point the energy is required. So if the central heating is set to 19°C then you are saving no energy by swapping a tungsten bulb for a LED bulb, you may be saving money as gas costs less then electric, but you are not saving energy.

In fact since the inferred energy from the light bulb heats you directly and not the air between, it means we can drop the air temperature and still be comfortable, so they could save energy.

The old folk knew how to heat the home without too much expense, you build the house over the pig sty, then heat from pigs heats your home, they also built a square of houses so in the centre it was wind free, the court yard. Even in 1980's we got the car port, idea drying area, no need for tumble drier.

Fitting LED, or discharge lights outside clearly saves energy, but inside they only save energy in the summer when heating is not used, and since we don't use lights as much in the summer, the saving is minimal. I have fitted all LED, or discharge lights around the house, but not to save energy, it is to save labour as it seemed every week a bulb would blow with old tungsten bulbs.

One easy way to save energy is paint all walls, floors, and ceiling white, so it reflects the energy back into the room, then you can reduce the lumen lighting in the room so save energy.

 

[ban-all-sheds]

I wouldn't call 20W energy saving

Everybody else would if the light output from it was the same as a 100W incandescent....