I also measured the 12 V transformer and another 24 V transformer directly. The 12 V hit 10 on the scale and the 24 V came to 20.

When in parallel and multiplying the outcome by 50 (meter set to 50) and calculated in a Watts/Volts/Amps/Ohms calculator online (enter 2 values says the calculator) I get to 0.09 Watt. That too sounds as impossible as the stated 10 or even 15 Watt from the suppliers.

 

When set to 50 DC the meter goes out gently to a resistance of 25 Ohm (top scale)

That looks right. Take the values on the red voltage scale and multiply by 5 (for 50V on a scale labeled 10V). I think that's roughly the same needle deflection where the 20Ω is. ~2.3 x 5 = 11.5V

 

Thanks, that's what I thought too but I still haven't figured out the Wattage.

 

Thanks, that's what I thought too but I still haven't figured out the Wattage.

Do you have a low ohms resistor you could place in series with the LEDs? Something like 10Ω or less would be ideal. It needs to be rated to more than the suspected wattage of the LEDs. Otherwise it might resemble a fuse - it might get hot and blow.

If you have such a resistor in place, you can measure the voltage across it when the LEDs are lit. By ohms law, this will give you the current through both the resistor and the LEDs: ∆V = I • R. You know R and once you collect the ∆V data you can calculate the current, I. Also measure the voltage across the LEDs. The power being consumed by the LEDs is P = ∆V • I.

If you cannot use the shunt resistor approach, we'll come up with something else.

 

Yeah ........ the multi meter has fallen apart ........ (Seriously)

I am going to get a better one and start again. Thank you all. I will be back here!

 

Yeah ........ the multi meter has fallen apart ........ (Seriously)

I am going to get a better one and start again. Thank you all. I will be back here!

A very inexpensive meter will do the job fine. This one is popular because Harbor Freight used to give them away free with a coupon. I have probably 6 of them. Anyway I'm perfectly happy with it. Of course I'm speaking from the view of a hobbyist - my career does not depend on the quality of my tools.
https://www.amazon.com/Function-Digital-Multimeter-New-Warranty/dp/B016F1ZXHM

 

Thank you but I already bought one. https://www.amazon.com/-/es/NEW/dp/B07YVLR1F1

The price from Amazon is USD 49 plus shipping but I bought it directly for 15 USD shipping included. I never buy on Amazon, don't agree with their employee conditions.

 

Hi Sofa, are these leds for the chickens? Like a night shift.
Good luck..

 

Hi Twohats!

Nope, they need a good night rest. The more relaxed they are the more eggs they lay. By the way, the light cell/actuators/all the electronics in the 3 coops work great!

These small spot lights are for the cinema. We used to have those fairy light strings but this time I got 50 mini red spot lights. They look absolutely great in the dark! At the moment we are working at the new place and we are not going to use the old lights anymore. The little spot lights just look soooooo cool! The interior is red and black so you can imagine that in the dark these tiny cheap thingies really make an impression!

Just want to make sure I don't connect too many to each transformer. I have done most of the electricity at the premises but that's all switches and buttons and new cables and 220V and I don't find that too difficult. Just never had a multi meter! I really have no idea how to measure the power consumption of something. If the vacuum cleaner says it's 1000 Watt I take his word for it and if I ran 10 at the same time I'd make sure they wouldn't all be plugged into the same outlet but the spot lights are a different story. I want to know how many I can connect to each transformer without running any risk. You don't want accidents in the dark.

I also built 42 clothing lockers and a stack of these cabinet lights (USD 0.84) They are rated as 0.03 Watt only but light up the inside of the lockers enough to make sure you don't leave anything behind. They're supposed to work on 12 V batteries but these are expensive so I have run a 30m fat cable from a transformer to all the lockers. Opened up the small lights and soldered 2 wires to the contact points, no batteries necessary. It's a hell of a job, so many holes and wires and terminal blocks and stuff but one more day and the job is finished. You open the door now of 36 lockers and the light comes on. It's bloody beautiful!

The wattage of these lights are not important, it will never happen all lockers are open at the same time. A few, yes. Just wanted to make sure the 12v reached the end so I used an impossibly thick cable.

 

Ok guys, the multi meter has arrived!

This is the one





Now .......... in what position do I put the knob to find out the power consumption of the LED? (Connected to a 24 Volt transformer) I take it I insert the black pin in the black hole and the red pin in the red hole on the right.

I have figured out the Voltage already, it's 24.4.

The meter is a TASI TA801B and I paid € 12.50 shipping included. (USD 15)

 

What makes you think your supplier lied?

Hi Anniel!!!

I think they're about 3 Watt but they're sold up to 15 watt. Many of these sellers just sell 'whatever sells' and often don't know what they're selling. Did the supplier I bought from lie? He said 3 Watt and that's probably correct. However, there are loads of sellers selling the same stuff and some even state they're 15 Watt. As I got 50 of these spots we are talking anything between 150 Watt or 750 Watt. Again, my guess is around 150 but since I bought my first digital meter I want to KNOW for sure!

 

Sure but the price is (almost) the same and the pics too so if it quacks like a duck .......

I need some stainless steel wide throw hinches and asked the supplier about the hole width. He answered that he didn't know because he hadn't measured it. Many sellers don't have stock, they just sell 'whatever comes along'.

In any case, I got 50 of these, 52 locker lights, about 100 meters of that glow in the dark stuff 'El Wire' and I made 1 meter large shop letters which now have a LED tube (some 40 meters in total) in pink and yellow on the side (looks fabulous in the dark!!!!) and a dozen 1.5 A to 36 A transformers and I want to connect it all the right way. It's a public place, lot's of wood and I don't want overheating transformers that employees forget to turn off at night. Nor do I want a transformer on each and every LED so the fewer the better but within the limits. And that's why I want to KNOW and not take the sellers 'word' for it.

 

That might be correct. (But I think the LEDs are 2835 type, the number of LEDs per enclosure may vary though)

In any case I think it's a wise idea to make sure I know the power consumption. I am reading the manual of the meter but it's late here. A day has 24 hours and this late I don't take all that info in. It's almost bed time and I've done enough today!

The automated coop doors work beautifully by the way. I had to adjust the sensor a few times as every few weeks it closed later although it was always very dark (weird!) but there no longer is any need to get up early.

 

Something you have to understand...no tests that you preform will give you the rated wattage of an LED.

The best you can do is measure the wattage being used at any given time.

Place the meter in current mode and place it in series with the LEDs...record current.
Remove meter place in voltage mode and measure the voltage across the LEDs record voltage.
Times the voltage by the current and you will have the wattage.

But, that is only with the resistor and supply voltage you choose...it's not the "RATED" wattage.

Choose a resistor that gives you the brightness you think is correct...do the test, then you can guesstimate the power supply you need.

 

A white LED has a forward voltage range of about 2.8V to 3.6V. Then 3 in series limit the voltage to 8.4V to 10.8V. If they are fed 12V with no current limiting then the LEDs are too bright, get very hot and "let the magic smoke out".

The seller told you the lights are "12V" but they probably work properly with DC and you say you have "transformers" that only produce AC that is completely different to DC from a DC power supply that has a transformer inside its AC to DC circuit. You said the light was not bright with your 12V "transformer".

Make this teat:
1) Make certain you have 12VDC when it is powering one light. Measure the voltage when it is lighting the light and adjust the voltage to 12.0V if you can.

2) Set the DVM to measure 10A of current (the red lead in the left hole) and connect it in series with the light. It will show the current. If it reads less than 600mA (0.60A) then test the current with the red lead in the right hole).
The light should not be much dimmer than without the meter.
12V x 0.125A= 1.5W. 12V x 1.25A= 15W.

 

ElectricSpidey

Thank you!

Audioguru again

I only have DC output transformers. AC/DC!

These sort of things.

I will report back here later, bed now! Thanks!

 

What you show is not a transformer, it is a power supply. Two very different things.

Bob

 

Here is a transformer:

 

Yeah, dude, like this one:

 

Guys, I have a question ........ I bought 70 m of this EL Wire stuff, glow in the dark. It's 12 Volt. Weird thing is that none work ........

I got a few 12 V power supplies, put some crocodile clips on the wire and ......... nothing! Got another wire, nothing!

Then I did some reading and read that these things are AC, not DC! I remember that many years ago I bought a kind of Pizza pan in Japan, 110V so we bought a 220 V to 110 V converter at home. The thing was equipped with a large steel handle to carry it, bloody heavy! It was also very expensive!

These EL Wire things are often used in cars, 12 V and that's DC as far as I know. I don't get this!

But if AC, how do I scale back from 220 V to 12 V without spending a fortune or was this 220 v to 110 V converter years ago so expensive because the Pizza pan was something like 3000 Watt and therefore the converter was powerful?

Or should I use one of the 12 V power supplies I have and convert the DC output with a ??? to AC?

EL Wire is like some 1/3rd of a Watt per meter only so 70 m is still only 23 Watt.