Question: sorry for stupid question but I do need help with connect of my ammeter from ebay. I bought this [Ammeter 0-50A](https://www.ebay.com/itm/0-36-Direct-Current-Digitals-LED-Digital-Display-Ammeter-Ampermeter-Panel/142521877008?ssPageName=STRK%3AMEBIDX%3AIT&var=441512420138&_trksid=p2057872.m2749.l2649) but there is no connection diagram 
So I try:

1. connect Vcc and GND to 9V and display turn on with value 0.0
2. connect white to negative, after load and black to gnd of load supply - but load (device) not work, it look like there is no connection between white and black thick wire. I try measure resistance and there is 5kOhms

If you look on photos there is some cooper wire between two holes on bottom, on other photos there is R050 but I do not have wire or ressistor on ammeter. 

Can somebody help me with connection ? Thanks
[![enter image description here](https://i.stack.imgur.com/I5U8B.jpg)](https://i.stack.imgur.com/I5U8B.jpg)

Answer: 
What this device must be doing is measuring voltage on this R050 (0.05 Ohm) resistor and converting it to the value of current. The device really misses the documentation, and as Leon said in comment to your question you either get documentation for it, or better junk it.

Red/Black wire pair *seem to be* the power supply for the board, power voltage is unknown, thus you can not be sure about its reliable operation unless you disassemble it, draw the circuit, and figure it out yourself, or read it in trusted documentation.

Thick Black/White pair seem to be the one to connect into the circuit to measure the current.

I wonder how much current the device can withstand as R050 resistor must be too weak and will just burn under high currents. Specification is scarce on it, and I guess `Measuring Range: DC0-1A, DC0-5A, DC0-10A, DC0-50A, DC0-100A` means different type of resistor/shunt soldered. Which one did you buy?

Finally, to be sure you understand basics - this device **measures current**, not voltage. It means that you can not just connect it to the poles of the power supply as it will cause enormous current and burnout of the shunt resistor. You **must** connect this current meter device in series with the load.

> 
> it look like there is no connection between white and black thick wire. I try measure resistance and there is 5kOhms
> 
> 
> 

Sounds like shunt resistor is dead.

**My advice: request documentation from the seller,** including connection diagrams.
You can solder a 50 mOHM = 0.05ohm resistor like on the picture. The tube is the same as a resistor. However be careful and find a through-hole resistor for high Amperes.

The tube is a resistor of a kind.

Or go after a 50 mOHM = 0.05ohm SMD like in the example.

So you undertand that's a SHUNT resistor to measure the current.
[![enter image description here](https://i.stack.imgur.com/EQqhs.jpg)](https://i.stack.imgur.com/EQqhs.jpg)

I edited my mistake.

An example of a shunt resistor to buy and a small guide for Shunt resistor.

[MOUSER SHUNT RESISTOR](https://www.mouser.es/productdetail/irc-tt-electronics/lr2512-lf-r050-f?qs=sGAEpiMZZMtlleCFQhR%2FzWv3A%2FxA%2Fyx6NUT73Nh4H88=)

[Guide](http://www.resistorguide.com/shunt-resistor/)