Mini LED panel Voltmeter connections

Thread Starter

Max12345

Joined Aug 27, 2013
63
Greetings
The first link is the one I have purchased. The second link just has more photos of the same item, but with Red LEDs.

http://www.ebay.com/itm/DC-0V-99-9V-3-wire-Mini-Blue-LED-Panel-Meter-Digital-Voltmeter-/121195040045

http://www.ebay.com/itm/DC-0V-99-9V-3-wire-Mini-Blue-LED-Panel-Meter-Digital-Voltmeter-/121195040045


http://www.ebay.com/itm/Red-LED-Panel-Meter-Mini-Digital-Voltmeter-DC-0V-To-99-9V-AT66-US17-NEW-CHEAP-/261306423512?pt=LH_DefaultDomain_0&hash=item3cd71398d8




I have purchased a mini 0V-99.9V DC Blue LED panel mount voltmeter which I have not received yet. I wish to use it on my power supply.
I have mailed the seller (in China) for a spec sheet, but I am not holding my breath.
Has anybody used this meter before?
Do you know or have the specs?
I would like to know whether it uses the same power supply that it measures or whether it should have its own isolated power supply. Is there a schematic available to do this if required?
Thanks
Max
 

mcgyvr

Joined Oct 15, 2009
5,394
it says it needs its own power supply
"Power supply range: 4V-30V"

It has 3 wires..
1 ground ground
1 power supply+ wire
1 measurement voltage wire
 

Thread Starter

Max12345

Joined Aug 27, 2013
63
it says it needs its own power supply
"Power supply range: 4V-30V"

It has 3 wires..
1 ground ground
1 power supply+ wire
1 measurement voltage wire
So it's not a completely isolated separate power supply for the meter, as it will share a common ground with the actual power supply?

Does this mean I should or can tap the meter's supply off the actual power supply? I'm unsure as to how to do a dual supply. Can you point me to a link please?

Thanks
Max
 

ErnieM

Joined Apr 24, 2011
8,007
So it's not a completely isolated separate power supply for the meter, as it will share a common ground with the actual power supply?
Yep, they share grounds.

The meter needs 4 volts to run itself, so if your P/S can adjust to zero you can't connect the power and sense wires, is will not work below the 4 volts

BUT... if you have access to the full supply you may well have a good point to tap, like the cap bank itself.

Does this mean I should or can tap the meter's supply off the actual power supply? I'm unsure as to how to do a dual supply. Can you point me to a link please?
For a single supply you put:
+meter power to +P/S cap bank
-meter power to +P/S return
meter sense to +P/S output


For a dual supply you put:
(+ side the same)

+meter power to -P/S return
-meter power to -P/S cap bank
meter sense to -P/S output
 

Thread Starter

Max12345

Joined Aug 27, 2013
63
Yep, they share grounds.

The meter needs 4 volts to run itself, so if your P/S can adjust to zero you can't connect the power and sense wires, is will not work below the 4 volts

BUT... if you have access to the full supply you may well have a good point to tap, like the cap bank itself.



For a single supply you put:
+meter power to +P/S cap bank
-meter power to +P/S return
meter sense to +P/S output


For a dual supply you put:
(+ side the same)

+meter power to -P/S return
-meter power to -P/S cap bank
meter sense to -P/S output
Hi ErnieM
Like this? As shown in the attachment? Is this OK?
Thanks
Max
 

Attachments

ErnieM

Joined Apr 24, 2011
8,007
Ahh, sorry I had assumed you were doing a +/- supply, not just a +

Yes, what you drew looks correct.

Since your transformer secondaries are separated, you can join them back together to make each one either a positive or a negative voltage (with respect to some common or ground).
 

Thread Starter

Max12345

Joined Aug 27, 2013
63
Hi ErnieM
I have to wait 6 weeks for the meter, so I don't want anything bad to happen to it, so just to be sure of the whole circuit, I posted it as an attachment for your perusal.

Thanks so much
Max
 

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