CCCmints
Well-Known Member
Sweet so then I could wire them up in series and measure both a/c & d/c.
Finally Got A Cob Lit Up! Multi-meter Questions
- Thread starter CCCmints
- Start date
nfhiggs
Well-Known Member
To figure out the DC current from the AC line measurements, you have to do a bit of math as well as knowing your power supply's efficiency factor. Measuring it directly is MUCH more exact.
The meter you linked to will do it directly - just not sure how accurate a $12 meter is going to be, but it will be at least as accurate as measuring the AC side.
To measure the DC current, you will put the meter in series with the strips. Connect the positive wire from the power supply to your red meter lead, then touch the black meter lead to the strips positive connection point.
CCCmints
Well-Known Member
What do you mean by 'strips'?
nfhiggs
Well-Known Member
I've got similar displays. I can't attest to those particular ones, but I can tell you the accuracy of some of these little displays is all over the map. The first one's I had worked well - they were close to the readings I got with my handheld multimeter. Then I got some more - different seller and slightly different displays - and they were not so accurate - they were off by about 50% compared to my multimeter. Then I went back to the first seller and got a couple more - they seem to be accurate like the first ones.
nfhiggs
Well-Known Member
I meant your COBs. Had you mixed up with another guy using strips. My bad.
CCCmints
Well-Known Member
Yeah, I'll probably just grab a meter in the $30-$40 range. It should be accurate enough.
CCCmints
Well-Known Member
So I failed in wiring up the multimeter with my COB. When I plugged the power in, the COB didn't light up. I made a diagram for the wiring to make sure I didn't fuck anything up in the first place: https://imgur.com/KfMS8iY
A/C In: https://imgur.com/d6aVoyk
D/C Out: https://imgur.com/Fs0ZXFe
Multimeter to COB: https://imgur.com/JyVDS6P
If someone could point out a mistake if they see one it'd be greatly appreciated.
A/C In: https://imgur.com/d6aVoyk
D/C Out: https://imgur.com/Fs0ZXFe
Multimeter to COB: https://imgur.com/JyVDS6P
If someone could point out a mistake if they see one it'd be greatly appreciated.
psychedelicdaddi
Well-Known Member
Where's the blue wire going on the dc out?
nfhiggs
Well-Known Member
On the AC In - connect the Black wire (on the plug side) to the Orange wire (on the driver side) and disconnect the red meter lead.
On the DC Out - Connect your Red meter lead to Blue wire from the driver output. It should light up and you'll get a meter reading.
CCCmints
Well-Known Member
It works!!! Thank-you!! The meter reads 1.380a for a 1.4a driver turned all the way up, so very accurate!
ANC
Well-Known Member
Use cheap meters in the middle of their range.
The only time it is worth dishing out on a Fluke is when you have to take very small measurements. fractions of ohms, currents, and voltages.
A meter with a limit of 10A will be most accurate around 5A. Ther is no reason for such precision here though, measure the voltage crosscheck the datasheet chart and that should be close enough.
The only time it is worth dishing out on a Fluke is when you have to take very small measurements. fractions of ohms, currents, and voltages.
A meter with a limit of 10A will be most accurate around 5A. Ther is no reason for such precision here though, measure the voltage crosscheck the datasheet chart and that should be close enough.
dstroy
Well-Known Member
Usually you only calibrate if you need accurate measurements to six digits, or microvolts (a millionth of a volt), in places where it is impractical to bring bench equipment, OR for critical applications where a hundred mV or mA would cook an expensive piece of equipment or kill someone. And then you do it annually. For our purposes it's completely unnecessary to spend $70 on professional calibration annually. Measuring amperage is accurate across the entire available range on all of the fluke meters that I've used, personally and for work.
The resistor arrays used for reference are very stable. If you want to learn more about DMM or electronics in general check out eevblog on youtube, dave does a good job of teaching.
The resistor arrays used for reference are very stable. If you want to learn more about DMM or electronics in general check out eevblog on youtube, dave does a good job of teaching.
nfhiggs
Well-Known Member
Yeah, Flukes are not known to be "drifty". Very seldom have we gotten word back from Tektronix (the cal vendor we use) that one of our meters was out of spec (they are require to notify us). When that happens its a VERY BIG DEAL. We have to re-evaluate all the items we have tested with the meter since its last Cal.
IMO, Calibration is something you need to do if you require traceability.