AC/DC Transformer with 240V output

[ThomsCircuit]

I am baffled. This transformer / LED Driver is 120V AC input and outputs over 200V DC. Probed with no load 246V
It is meant to drive a 12 inch ring of leds. Why so much for a small amount of LEDS?

"awesome solder skills"

 

[Papabravo]

The device is an offline AC to DC converter, not a transformer.
The high voltage is meant to overcome the sum of all the forward voltage drops for the LEDs. How many LEDs are there?
There is something wrong about the numbers listed on the device:
1) 110 V x 0.275 mA ≠ 18 watts. It is more like 30 mW
2) 178 V x 0.093 mA = 16.55 mW, which means the thing is pretty inefficient, just over 50%. That is piss poor in my estimation.

 

[ThomsCircuit]

so if I wanted to replace this device with a better quality one what would I be looking for ?

 

[ronsimpson]

I wanted to replace this device with a better quality one

What is wrong with the one you have?

 

[ThomsCircuit]

It looks so poorly made. Just want one one that I can trust.
What do i need to do to calculate the existing LED tube lights requirement?

 

[ThomsCircuit]

So if I wanted to replace this would I need a transformer with a 240V 16mA output?

 

[rjenkinsgb]

That is a custom designed LED driver. Without knowing the exact specifications of the LEDs its connected to, replacing it with anything else is likely to damage the LEDs or the replacement PSU.

As others say, it is NOT a "Transformer". It looks fine to me; it is simple as it uses an all-in-one high voltage switching / regulator IC. "TOPswitch" style.

The voltage and current may be maximums - if it is a constant current device, the current could be the same at much lower voltage when connected to a chain of LEDs.

 

[Nigel Goodwin]

The device is an offline AC to DC converter, not a transformer.
The high voltage is meant to overcome the sum of all the forward voltage drops for the LEDs. How many LEDs are there?
There is something wrong about the numbers listed on the device:
1) 110 V x 0.275 mA ≠ 18 watts. It is more like 30 mW
2) 178 V x 0.93 mA = 16.55 mW, which means the thing is pretty inefficient, just over 50%. That is piss poor in my estimation.

You've messed your maths up - the output is rated at 16.55 watts (not milliwatts).

However, you can't simply do the same for the input, the specification for the current will be the MAXIMUM - not the normal running current. It's a standard constant current LED driver, and will be reasonably efficient.

I don't see the OP's issue?, his mistake is trying to measure the output voltage of a constant current supply with no load - connect it up properly, job done.

 

[alec_t]

There is something wrong about the numbers listed on the device:

I agree. An output current of 0.093mA is nonsense. Probably a typo for 0.093A.

 

[Papabravo]

You've messed your maths up - the output is rated at 16.55 watts (not milliwatts).

...

Wrong! What I did was miscopy the information from the device label. I have corrected it in my original post. and it is milliwatts.

 

[Nigel Goodwin]

Wrong! What I did was miscopy the information from the device label. I have corrected it in my original post. and it is milliwatts.

I don't know what you're on about, and your original post doesn't seem to have been corrected - the output current is obviously in AMPS - not milliamps, and everything then makes perfect sense.

 

[ThomsCircuit]

Thank you for your input, and output .
Ill connect the led ring and probe the load.
Like always, you folks have helped me solve another problem.
T.B.

 

[Papabravo]

I don't know what you're on about, and your original post doesn't seem to have been corrected - the output current is obviously in AMPS - not milliamps, and everything then makes perfect sense.

You can certainly be dense on occasion. Just read the label on the device and tell me it says what you think it says. Oh and when I look at post #2 it appears to have been corrected. So I guess I have no clue what you are on about Massa Goodwin.

 

[Nigel Goodwin]

You can certainly be dense on occasion. Just read the label on the device and tell me it says what you think it says. Oh and when I look at post #2 it appears to have been corrected. So I guess I have no clue what you are on about Massa Goodwin.

The label on the device is obviously misprinted - surely you realised that?, how bright do you think LED lights would be fed with only 93uA

And post #2 still has the wrong current - so changed, but not corrected.

 

[For The Popcorn]

2) 178 V x 0.093 mA = 16.55 mW

I have to agree that common sense (so little of that is demonstrated here) rules in this case. The mA has to be a typo and should be Amps. LEDs are pretty darned efficient, but even a 5mm LED isn't going to operate at 0.093mA, let alone higher power LEDs designed for illumination.

 

[Tony Stewart]

Bad engrish translation.

This should output read 93 mA or 0.093 A and my reverse engineering on photo says it will be 100 mA.

The two bulk caps in series are rated for 250V so it can tolerate 500V * 80% (from tolerance mismatch)

No-load higher voltage is always higher when the max number of LEDs in the string limits the voltage.

I roughly estimate 3.3V per LED and think this can drive up to 54 series LEDs with constant current.

What does the customer datasheet say for the number of LEDs minimum in series?

This is just a simple 100 mA linear current limiter using 7.5 Ohms across 0.75 Vref meaning the IC will get hot as a low dropout linear regulator if the dropout is not "low" meaning if you do not have ~ 54 white/blue LEDs in series = 178V out, with a load of <= 16.5W, the IC will burn up. This is a product "worth about 25 cents". and consumer cost about $5 more or less is a ripoff.

It is meant to be around the ceiling perimeter of a home theater out of reach by hand for non-insulated electrical hazards and not safety approved.

Look for something worth about 25 cents per Watt with full engineering specs for minimum and maximum LED power current and voltage.

 

[ThomsCircuit]

What does the customer datasheet say?

no data sheet. I was given two of these and two diffused LED rings 12" in diameter. One driver was bad so I connected both tubes to one driver. If I look close enough they are spaced 5/8" apart so that would be about 60 leds. and that would come to 198 volts.

 

[ThomsCircuit]

would this be a good replacement or does the output voltage need to be higher?

 

[Tony Stewart]

Without LED Lamp detailed specs, I cannot recommend anything.

I expect your estimate of 80 LEDs in a 12" ring is actually wired for low voltage DC such as 24V, 1A = 24W

Thus if they are good quality LEDs @ 3V / LED instead of 3.3V ( cheap quality) then it will be 8S (series) and 10P (parallel)
or 8S10P array.

If you had such a brick or adjustable $50 lab supply to test this on or 3 x 9V cells = 27V max in series to do a low tech test it will drop in voltage under load.

 

[ThomsCircuit]

Without LED Lamp detailed specs, I cannot recommend anything.

ill reach out to the manufacture. See what they have to say.