Digital Ammeter Not Reading Amplifier

[Camerong]

I've got my led lighting, usb charger and tpa3116 amplifier in a curcuit with all the negatives tied to one and going through a digital Ammeter. It picks up both the usb charger and the leds but not the amplifiers current.
What could be the problem?
See diagram attached

 

[Michael Bean]

Learn how to use an ammeter: Basic Ammeter Use : Basic Electricity Worksheets

Mike

 

[Camerong]

Ah right so ammeters can't be in parallel. Has to be series

 

[Camerong]

Wait no mine is. I can't think what would be going wrong

 

[Michael Bean]

If you want to know the current through the amp, the ammeter should be in series with the amp alone. If your trying to measure the current draw of all three keep in mind the current requirements of the amp is probably much greater than the other two, and may not be getting enough current to "start up" if you have the ammeter set to a low current range. Try the amp alone with the ammeter set on the highest current range. If that works, add the other two devices and keep the meter on the range that worked with the amp.

Mike

 

[Camerong]

Thanks Mike. It's one these ( see picture).
It's got a 10A range non adjustable.
The amplifier runs and plays music but no current displayed.

 

[Michael Bean]

Nothing at all? Are you sure the meter works correctly? Try testing the meter's 10 amp range with a power supply in series with a power resistor sized to draw an amp or so (10 volts across a 10 ohm/10 watt resistor will cause one amp to flow for example) and see what it reads.

Mike

 

[Camerong]

Sorry picture didn't go through.
I don't have a variable power supply, so I can't do that. It is picking up something,
I think ammeter is picking up the amplifiers quiescent current. Or it might be the ammeters current only 50-100mA I'm not sure

 

[Camerong]

Btw I think the ammeter is working correctly as the charger is drawing out 500mA and the leds around 300mA.
The ammeter is right on both of those

 

[horst303]

maybe it's just not enough current to bother it.
I actually just got one of these to measure lower range current
NEW DC 0 300V 999mA 1A Dual LED Panel Meter Voltmeter Ammeter Volt AMP Meter | eBay

 

[Camerong]

It should I mean the amp must draw at least an amp. If it show the lights and charger current. As MIke said it would draw more the most current

 

[nigelwright7557]

The quiescent current of the amp could be as low as a few 10's of milliamps.
Connect a speaker and play music loudly.

 

[Camerong]

I have doesn't change anything ae.

 

[horst303]

which 3116 is this? you will find that it will play loudly at 0.1A

 

[Camerong]

Its a sanwu blue.
That's good to know

 

[Camerong]

I put it through my multimeter instead and it says about 0.1A. Man this amp is crazy. I've got a 12v 12ah battery inside and that means it'll last at least 60hours. That can't be right ...surely! Haha

 

[horst303]

There we are that current panel meter is bung.

Try getting two 12V of half the size, or hell another battery of the same capacity and run them in 24V, then the amp is really going to sing.

 

[Camerong]

Yeah or I might change the psu for a higher voltage one.
I've made a curcuit that when I unplug the mains power it switches over to the battery then when I have power it switches over to the psu. Do you think If I have a 24v psu and a 12v battery unplugging it all of a sudden things could go wrong. Going from 12v to 24v or visevera

 

[Camerong]

I've got a relay in the curcuit. It's a frc1 bc 2.
Do you think Ithat will be ok at 24. Should be I'd say

 

[jan.didden]

Did you consider that the amp draws pulsating current, not DC, and that the meter may not be able to measure that?

Jan