Pre-sales Answers of Frequently Asked Questions for LCD Voltage、Current Meters:

1. Our LCD Voltage、Current Meter usually requires a separate Power Supply to work promptly; generally it requires a 9-12v aid Direct Current (DC) or AC Power Supply. 

   For meters with 4-wire are all need Power Supplies.

All of the ammeters including DC and AC are require aid Power Supplies. 

   All voltage meters which need to measure starting from 0V require aid Power Supplies;

2. Part of the specification does not require the power supply, meters with 2-wire are not require power supplies; Specifically, there are three kinds of ranges for measurements: measure AC 80-500V range, measure DC 7.5-19.99V range, and measure DC 7.5-30V range. 

3. Currently, power supply for the meter can be AC 9-12V; you can use a small power transformer to provide power.

   For ammeters whose ranges less than 5A, do not require shunts or transformers;

   For DC meters whose ranges above 5A, do require shunts;

   For AC meters whose ranges above 5A, do require **/5A transformers;

4. For ammeter which has different ranges, if its decimal point is in a fixed position, it cannot be moved after shaping.

5. The precision of voltmeters are generally higher than ammeters, the most accuracy of voltmeters are level 0.5, part of the 2-wire voltmeters’ accuracy are level 1.0;

6. The accuracy linear of ammeters is generally not very good; it needs to choose small-scale range, for example, use 0-199.9MA; If the range is wider, one side of the error is relatively large;

After-sales Answers of Frequently Asked Questions for LCD Voltage、Current Meters:

1. For meters with 4-wire, each meter must separate power supply, you cannot use the same power supply:

Separate power supply and you cannot use the same power supply means that the electrical power to be measured cannot work with a meter’s power supply in a same circuit; You cannot use the same piece of battery, or with a transformer for two or more of the same type of power supply when you provide power to the meter at the same time;Meanwhile, a battery can only supply to one meter, a transformer can only give power to one meter;

For example, the following practices are wrong, they are not allowed:

a.    One battery for many meters

b.    One transformer for many meters

c.    Take the battery’s power to the meter to use, meanwhile measuring the battery’s voltage or current piece

d.    After taking AC all the way through a transformer, light bulb and supply power to the meter at the same time

e.    After taking AC all the way through a transformer, supply power to the meter and measure the output voltage of the transformer

2. The meter displays 1 after connected to the circuit, what is this mean?

   This means that the range is greater than the nominal or rated range; or wiring error,   

   there is no separate power supply;

3. After connected with voltmeter, there is no display except backlight only?

    a. No separate power supply. Please see the content of number 1 under After-sales Answers of FAQ;

    b. The actual input current or voltage is too small, for example, the range of 10A meter only has 10ma of current input;

4. The consequences of error connection:

    Some of the products will display 1, while some will not display anything directly, and some products will smoke black, capacitors burst will be individual cases which lead to product obsolescence. So please make sure to carefully check the wiring instructions before connecting. 

5. DC meter does not indicate positive and negative pole, it is not required to distinguish between positive and negative

Power supply 9-12V, does not require to distinguish between positive and negative,it can access directly;   

Measurement side, the meter will display negative if connection is reversed, but it will not burn; (DC with 2-wire

 needs to distinguish between positive and negative pole).