Multimeter use on bridgelux 1 foot setup

[clayts]

Hi all,

Finally finished building my bridgelux eB series 2 build. Pretty much followed the 2x2, 1 Foot suggestion from this site, started almost a year ago and finally (after learning how to solder) have wired up the potentiometer and hung the light. Awesome.

Now, the one thing I did do differently is that I opted for the hlg-150-20B driver. Thought I'd build in extra power in case I want to upscale a tiny bit.

So I'm just trying to test exactly how much to dim these strips. I've managed to test the voltage with my multimeter. Interestingly, without dimming they range from about 19.8V at the 'far end' to 19.9V at the closest strip to the driver. These values actually drop by as much as 2V if I dim it all the way down.

What I've been having trouble with though is measuring the current. I can't seem to get my head around how to wire the multimeter in series with the pot so I can see the current changing as I dim it. Everything I've tried so far just makes the light turn off. I'm assuming this is because it is either in parallel or shorting it out.

Would someone be able to either describe the actual wiring or a diagram for me? I have the dimming wires coming from the driver, into wagos, then wires coming out of those wagos soldered to the pot. Where exactly do I connect the multimeter probes to measure the DC current?

Thanks all. This site has been so good. Not only has it helped me build a light, but actually have me the confidence to learn all these new skills and gave me a project to concentrate on for many weekends (small child makes it difficult to spend much time on it). I've quite caught the electronic bug too. Next project is a weather station with a raspberry pi.

[QuantumMechanic]

When measuring the current, the meter leads are put in series with the leds and the driver. Break the circuit at this point and install the meter at this break. Note that this is very different than measuring voltage, which is done in parallel.

Generally the meter leads will have different holes in the meter to plug into when measuring current. Be careful to avoid measuring voltage when the meter leads are set up to measure current. This will cause a short circuit.

Don't worry too much about getting the polarity of the meter correct when hooking it up. If you get it backwards, it will just read out a negative DC current.

[clayts]

Thanks for that reply.

Yeah I understand that the circuit has to be broken and that the multimeter has to be wired in series to measure current (also understand that this is different to measuring voltage) but what I'm after is the actual way to do that. As in, the actual way to wire it in series. Where exactly would I place the probes?

[Hydrofood]

Where exactly would I place the probes?

Read this.
http://ledgardener.com/use-multimeter-c ... d-circuit/

Watch this.
http://ledgardener.com/diy-led-multimeter-basics/

[xenophon]

It is really worthwhile to invest in a clamp-down amp meter. No breaking the circuit and adding massive resistance! I borrowed one of these from a friend and it's my favorite new toy. I watch amperage at every wire all the time. It has really helped me fine tune my Meanwell A driver which tends to make its own decisions once it heats up, if not calibrated just so.

[Hydrofood]

It is really worthwhile to invest in a clamp-down amp meter

That's funny you mention it being a worthwhile investment, meanwhile you are borrowing one handed to you by a friend! Haha that made me laugh a little. Just kidding around brother.

Unless someone's using a really cheapo multimeter, the internal resistance (burden voltage) is negligible at the currents we are measuring.
A high quality, proven multimeter was the VERY FIRST purchase I made when I began my DIY LED light journey. Burden voltage was one of many key factors in making the choice I did. I have several meters from years past that work perfectly well, just that none of them had a particularly low burden voltage.

I'm in no way saying you shouldn't buy a clamp meter, because frankly, I want one! They are very handy and I like the fact you don't have to break the circuit.

Just make sure you know the accuracy range of any meter you use. You might come to find out that your measuring with only 10% or even 15% accuracy. This could potentially have significant impact.

What exactly is going on with your driver once it heats up?
Is this a continuous problem your facing? Having to calibrate and adjust each time it heats up?
Which driver do you have in particular?

[xenophon]

Well, once I borrowed it I realized that the second its returned I will be going to the store to buy one. Especially working with these Atreum quantum-style boards. I have two of those wired in parallel to a HLG-240H-54A,

I find the voltage pot is tough to control with a 5v range. And there was a learning curve with the clamp meter, some early readings were less than accurate, as you say, especially as I was just barely overloading the 2amp setting. In addition, I have never used a driver like this before, being accustomed to constant current sources for LEDs. I am still getting over all this parallelism. Anyway, I have gotten much better at working the voltage and current controls together to fine tune it. Everything is under control now.

[QuantumMechanic]

Most of the inexpensive clamp-on Ammeters are for AC only. They're useful to see how much current the combination of the driver and LEDS are pulling from the wall. I use a Killawatt meter for that and it works well as my light only has one driver.

For current measuring on the DC output side of the driver, a multi-meter with leads is the better way to go.

I have both AC and DC clamp-on meters that I needed for work. I've never used either with my light.

[xenophon]

Most of the inexpensive clamp-on Ammeters are for AC only. They're useful to see how much current the combination of the driver and LEDS are pulling from the wall. I use a Killawatt meter for that and it works well as my light only has one driver.

For current measuring on the DC output side of the driver, a multi-meter with leads is the better way to go.

I have both AC and DC clamp-on meters that I needed for work. I've never used either with my light.

What's inexpensive? The Ammeter I am using sells for $50 at Amazon. There are $30 ones that are less precise at lower amperage.



Why do you think it's better to use a multi-meter? I can measure the DC output, return, and points between in minutes without disturbing the circuit, using the ammeter.

[QuantumMechanic]

Looks like the technology left me in the dust... When I bought my DC clamp, it was four bills. The AC one was only 85. Both have analog meters.

$50 is pretty good if it's accurate.

I stand corrected.