How to wire digital dual display volt- and ammeter
Once I bought a popular “Chinese” volt- and ammeter gauge with 100V/10A ratings. Unfortunately, I didn’t find any good resource about how to wire/connect it. Actually, it’s not rocket science, but I had waited for it 2-3 weeks and didn’t want to blow it at first try. All the diagrams were somehow too technical for me.
The original article included only one variant of these digital volt- and ammeters. Now I have included three most common variants of them. If you order digital 100V/10A volt- and ammeter gauge from China or other markets – it’s most likely one of the following.
They all have a bit different wire colors. I will cover wiring for all of them in this post.
These meters are good when you want to measure current and voltage at the same time. A feature that usual multimeters lack. For example, I have used it to measure the output of my DIY solar panel. They are inexpensive and easy to connect.
How do these ammeters work?
These meters calculate current flow by the voltage drop across the shunt resistor. They have built-in shunts that should withstand measuring as much as 10 amperes. You must see shunt behind your volt- and ammeter. That small bridge bent from a thick wire on PCB.
Important! If there is none- this guide is not for you. You need a wiring diagram with an external shunt instead. Also when measuring current that exceeds 10A which can be handled with the internal one.
They are basically the same. There is a connector with thick wires and connector with thin wires. But coloring of wires vary. Amperage measurement is done by passing power through thick wires. Power to the meter itself is fed through thin wires.
They all can be wired such way that you don’t need a separate power supply for the electronics part. You can use the same power supply where your measured load gets electricity. But then you can only use a maximum of 30V since it’s the maximum operating voltage for the meter itself. Also, you can’t measure voltages below 4.5V. If using the same power supply you even can leave thin black wire un-connected since they have common ground/GND.
Reversing polarity on these meters?
You can’t reverse polarity on these meters when measuring amperages (probably voltage also). I tried this on the first one in the list. It shorted out. It’s probably because of the common ground and by reversing you are feeding positive voltage into GND connection. If someone has some other info please let me know.
Also important! You CAN’T read current in the reverse direction with these ammeters.
Wiring of dsn-vc288 with thick red and black wires + thin yellow, black and red
Wiring dsn-vc288 makes the most sense to me and seems to be most popular also. It also has clearly marked model name on the PCB which makes it easier to identify.
Red, black and blue thick wires + thin black and red
This exact one was in my original article. Not very popular anymore I guess since can’t find many offers for these.
Red, black and yellow thick wires + red and black thin wires
Important! I have not tested this one myself. If someone can confirm this is correct I would be very thankful. From the info I found from sellers and one youtube video- this one has a bit tricky coloring. The voltage sense line is also a thick wire and it’s not yellow. It’s a red one instead!
Can someone please confirm this schematic is correct?
Here are some photos of testing them
One test with the external power supply
When there’s no voltage on the blue wire to the load what would be the cause?
Is it a faulty amp/volt meter?
Nice tutorial mate.