Volt/Ammeter Question.

** Far more likely, the light red/black wires are for the meter itself: 4.5 to 30V supply, red = positive.

The heavy red/black/blue wires are for measurement: red = 100V, blue = 10A current with black as common. The red and blue LED displays are the clue.

Check if the black wires are linked internally, ie they test zero ohms.

.... Phil

LED driver module? Oh well good luck. If it really is independently adjustable voltage and current then it might work, but if it's designed for LEDs, the designers probably won't have worried much about noise on the output.

I couldn't say for sure, but I expect the small wires are the power for the meter itself, and the thick wires are all for taking the reading.

At a guess, the thick Red wire is for voltage (which it displays in Red), the Blue wire is for the Current Shunt (as current is displayed in Blue), and the thick Black wire is ground.

The Thick Red wire would go to the bench supply's positive output, the thick Black wire to the ground connection of the LED driver, and the Blue wire to the Bench supply's Ground connection.

Measure with a multimeter to see that there is a very low resistance between the thick Blue and Black wires, and a high resistance between the thick Red wire and both the thick Black and the thick Blue wires.

Low = Less than 3R High = More than 100K

The small wires should go to the output of the laptop power supply, in parallel with the LED driver, as long as the laptop supply doesn't (by some strange occurrence) supply more than 30V (the maximum supply voltage they say the meter's rated for).

--
__          __ 
#_ < |\| |< _#

I've got a few of them here.

Actually the thin wires are to power the LEDs and the measuring circuit, the thick ones are for the metering.

the ammeter in in series with the negative supply. blue being the negative output, red being the common positive and black the negative input.

I could have blue and black transposed, if the amps always reads zero swap them (the device will not be damaged).

connect the thin wires to your 20V input (the thin black is internally connected to the thick black, so you can't use a DC-DC converter that generates a voltage between negative in ans negative out, most don't)

--
  \_(?)_

Thanks a lot Jasen, good to know. I might explain it in the feedback I give on AE (once I know for sure).

--
Shaun. 

"Humans will have advanced a long, long way when religious belief has a cozy  
little classification in the DSM*." 
David Melville (in r.a.s.f1) 
(*Diagnostic and Statistical Manual of Mental Disorders)

Cheers Phil, appreciate the advice. Apologies for the late reply, yet another case of real life intruding. ;)

--
Shaun. 

"Humans will have advanced a long, long way when religious belief has a cozy  
little classification in the DSM*." 
David Melville (in r.a.s.f1) 
(*Diagnostic and Statistical Manual of Mental Disorders)

Yeah it really is. I've used it on several high-power LEDs ranging from a 3W IR to a 30W COB led. Testing with the DMM shows that adjusting the trimpots adjusts the voltage and amperage respectively without changing the other parameter.

It's got a 470uf / 35V cap and a choke made up of a 15mm ferrite ring with ~50 turns of wire on it as part of the output filtering. I'm not sure if the main switching step-dowm voltage converter is an LM259 (150Hz) or an XL4005 (300Hz) as there's a heatsink on it (as well as a bigger heatsink on the other side of the PCB). The module is 55 x 36mm and comes with 4 x 10mm stand-offs fitted.

Anyway if noise might be an issue I can always throw a few (more) caps across the output, maybe in a cascade arrangement and another choke. After all I'm making this thing. ;)

Thanks. As mentioned the laptop PSU is rated at 20V and I measure 20.4V as a no-load output.

Cheers,

--
Shaun. 

"Humans will have advanced a long, long way when religious belief has a cozy  
little classification in the DSM*." 
David Melville (in r.a.s.f1) 
(*Diagnostic and Statistical Manual of Mental Disorders)

Once upon a time on usenet ~misfit~ wrote: [sipped]

Gah! Obviously that should read 150KHz and 300KHz respectively for the LM259 and XL4005.

--
Shaun. 

"Humans will have advanced a long, long way when religious belief has a cozy  
little classification in the DSM*." 
David Melville (in r.a.s.f1) 
(*Diagnostic and Statistical Manual of Mental Disorders)