lektor January & February 2021 85user guide instructions for this module. A little bit of searching
revealed that it is used for selection of the external 12 V supply
voltage. In the 3W position an external 12 V supply is necessary
for operation of the measurement module. In the 2W position the
module can derive this voltage from the connected power source,
as long as the voltage is between 10 V and 30 V. The module tested
functioned down to 8 V.The wireless connection is very convenient for keeping an eye on
something from a distance. I powered the display module from a
small powerbank, allowing me to walk around the house with the
module. You have to be careful with the distance (10 m max.) since
the range drops quickly if there are a few walls between the display
and measurement modules. However, the display module includes
a signal strength indicator that makes it easy to monitor this.Conclusion
This set of measurement and display modules is very handy and
affordable for measuring voltage and current in all sorts of circuits.
Thanks to the large current range (30 A), it is ideally suited to situa-
tions with high current levels. The ability to use the wireless display
module in one location, while measuring the data somewhere
else, is a valuable extra feature that you would scarcely expect at
this price. This combination of capabilities is certainly worth the
price of around €40/£35/$45.
200571-02(primary or rechargeable), you can use this to keep track of how
many ampere-hours it has supplied. You can also work in the
opposite direction, with the load replaced by a battery charger.
This then shows how much energy has been supplied to the battery
(Figure 3).
There are a number of menu settings that are especially interesting
for use with rechargeable batteries. For example, the upper and
lower limits for switching off the relay can be defined. This can be
used to avoid deep discharging of the battery when it is powering
a load, or overcharging when it is being charged. You can also set
a maximum positive current (from the power source to the load)
and a maximum negative current (from the charger to the battery)
for switching the relay. With this combination you can easily keep
track of how much power a connected circuit uses, or how much
energy was stored in a battery during charging, without having to
resort to a calculator. The battery icon can also be hidden if you do
not need it in a particular application.
Practical experience
The JOY-iT user guide included with the device provides enough
information to get you started, but to learn how to use all the
features properly we recommend that you try each functionality
in the list of menu items.
The measured voltage and current are shown on the display with
two digits before the decimal point and two digits after (Figure 4
and 5 ). According to the user guide, the accuracy is ±2% for voltage
and ±5% for current. This turns out to be reasonably correct in a
comparison test with an accurate multimeter. Unfortunately the
display module shows a small voltage even without an input voltage
applied, which is a pity. Although it is within the 2% accuracy speci-
fied, it does seem a little strange.
The connector PCB in the measurement module has a jumper with
positions marked 2W and 3W. This jumper is not mentioned in the
related products
> JOY-iT VAX-1030 Wireless Multimeter
http://www.elektor.com/joy-it-vax-1030-wireless-multifunction-meterFigure 4: The display module showing the default screen. Figure 5: After touching a button, a more detailed display including a menu
appears.