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Topic: Wemos D1 Mini R2 5V VIN (Read 3233 times) previous topic - next topic

nicedevil

I'm not clear on how you are connecting the meter. It must be in line with the current flow, so that the current that lights the LEDs is flowing through the meter.
It does ;)

And sure I turned all the LED on in White to get max readout.

PaulRB

#16
Jan 03, 2020, 12:43 pm Last Edit: Jan 03, 2020, 12:48 pm by PaulRB
The black wire is hold on the GND and the red wire is hold on the 5V PIN on my LEDs, the multimeter is set to 10A and the socket with 10A is used as well.
OK, let me put it another way. It sounds, from the description you gave, like you are connecting the meter incorrectly. It sounds like you are shorting all the current available from the psu through the meter, and may have blown the fuse in the meter. If your power supply is less than 10A, you may have damaged that also.

To correctly measure current, you must connect the meter as part of the circuit, for example with the red probe to the + terminal of the PSU and the black probe to the + connection on the leds. Leave the ground/- connection from the PSU to the leds connected directly by wire.

ShermanP

I am puzzled as well.  If you tried to measure current by connecting the probes to 5V and Ground, you probably burned out a fuse that's inside your meter, and will need to replace that before you can measure current at all.

PaulRB

Exactly. And unfortunately, many cheap meters (including my meter) don't have a fuse on the 10A input, only on the other input (e.g. 250mA fast blow).

However, I would imagine that if your blow the 10A input, there would be obvious signs that you had done something wrong, like very hot, very bad smells. You would notice. So hopefully you have not done that.

Paul__B

Are you aware of any meters which do have a fuse on the 10 A terminals?

The fusible rating of the actual shunt itself would be more like 30 A (100 mV at 10 A is 1 W dissipation, it would require 30 A to dissipate 10 W) and the PCB will most likely fuse first.

PaulRB

Are you aware of any meters which do have a fuse on the 10 A terminals?
No, I assumed/hoped that more expensive meters than mine would have some protection on that terminal.
The fusible rating of the actual shunt itself would be more like 30 A (100 mV at 10 A is 1 W dissipation, it would require 30 A to dissipate 10 W) and the PCB will most likely fuse first.
Ok, agreed. So why do you think nicedevil's meter read zero when he shorted out the PSU with it? (Assuming that's what happened, according to his description?)

Paul__B

Frankly, without pictures or clearer explanation, I simply have no idea what he did/ has been doing.  :smiley-eek:

Ever the problem here.  :smiley-roll:

nicedevil

the meter is fused :D and so I did it wrong hahaha :)

fuse is still ok mhh maybe because it is a cheap one.

My Idea was to measure the mA of my 7 LEDs. So black wire from black port on the meter to the +5v on the LEDs and the red wire from the red mA port to the +5v of the arduino right?

PaulRB

Yes. Do you get a reading that isn't zero? Do the LEDs light?

nicedevil

#24
Jan 06, 2020, 02:18 pm Last Edit: Jan 06, 2020, 09:01 pm by nicedevil
So here are my measurements, think I'm doing it still wrong :D

Just 40-50 mA on 255 brightness and all LEDs maxed out?







PaulRB

Please post images as described in the forum guide!

Two of your thumbnail links lead to the same image.

nicedevil

Please post images as described in the forum guide!

Two of your thumbnail links lead to the same image.
kk will take a look at this for next posts :)

For now i fixed the wrong link.

PaulRB

Looks to me like most of the current to the LEDs is going through that red wire. Only a small part of the current is going through the meter. Disconnect the red wire.

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