Can a microcontoller be used to replace the "dial knob" function in a 'off the shelf' multimeter(10A max AC/DC). Is it easy to scale and micro control multiple identical multimeters using one microcontroller? All multimeters operating mode is to be set using one centre dial which the microcontroller reads. The rest of the multimeters simply stack behind the top most device with their shell/case taken off.This will save on the bulk of the device shape and "streamline" whatever blob comes out in the end. DiY x-Channel Multimeter - Hope it's a clear visual :)

The dial itself works by simply bridging between many pads on a PCB(check photo). Can the dial(mechanical) be bypassed by micro controller with ability to set the full range of combinations that the dial currently bridges?

The microcontoller would have to remember the active settings for each individual multimeter dial position and maintain them independently.

Would be good if there is a way to only power the micro controller upon need to change settings and power off immediately after setting the relevant multimeter board IC. Saves battery (1x9v)

It is desirable to have everything readable in one glance and therefore all LCD displays are to be lifted off the multimeter PCB and placed to sit all next to one another on the top surface of the combined device.Allows for easy tracking of everything in one place without losing sight of the work area.

How far can the LCD be lifted off the PCB? as the photo shows the LCD is a generic type component... Has anyone tried separating the LCD from a PCB? What max distances can be done?Is 10 cm a possibility?

can this work ? dial pads on multimeter

multimeter circuitry

  • \$\begingroup\$ (1) Nick, this sentence "So if I have 4 multimeters I would like to add 4 buttons on one multimeter and use them to chose which multimeter the dial sets." seems to be garbled. Can you fix that in your post. (2) Why don't you explain what you are doing this for so we can come up with a good solution? (3) You forgot to explain whether you're measuring voltage, current or resistance, etc., and this will affect the answer. Put all the information in your question and not in the comments. \$\endgroup\$
    – Transistor
    Aug 7 '16 at 8:40
  • 7
    \$\begingroup\$ Wouldn't it be more sensible to buy multimeters with a GPIB (IEEE 488) interface and control them from a computer. The method proposed in the question appears to be such a total bodge and likely to degrade performance so much that it's just not worth the effort. Please justify why you think the method you propose is the only possible work-around. \$\endgroup\$
    – Andy aka
    Aug 7 '16 at 9:17
  • \$\begingroup\$ Good question and it's definitely ahead in terms of where I was next planning on taking this thing - micro controller to computer in realtime. I might not have a good enough answer after reading your comment. Why do this? Before anything else Its to to develop skills and feel confident in my ability to modify any device or number of devices(with due precaution). Secondary Portability, cost , easy scalability . That was before your comment and now I just want to know that GPIB multimeter can compete well on : price, portability(size and battery life),easy scalability and I'll be on that route \$\endgroup\$
    – Nick
    Aug 7 '16 at 9:44
  • \$\begingroup\$ @Transistor Thanks for spotting this. Reworded now :) \$\endgroup\$
    – Nick
    Aug 7 '16 at 10:06
  • 1
    \$\begingroup\$ some meters have RS232/serial which is even easier to come by than GPIB. \$\endgroup\$
    – old_timer
    Aug 7 '16 at 14:31

Can a microcontoller be used to replace the "dial knob" function in a 'off the shelf' multimeter(10A max AC/DC).

On some ranges perhaps, depending on how the meter uses the switch contacts. Some contacts may be used to route analog signals that cannot easily be switched with a transistor or analog transmission gate. You need to determine what every contact does, which will be tricky unless you have a complete circuit diagram. If you are not careful the meter's accuracy could be compromised - or worse, something might blow up (if it can't handle the voltage and current being switched). So you may need a combination of transistors, gates, optocouplers and/or relays to get full functionality - quite a mess!

I would do it the easy way - mechanically. Attach a small geared stepper motor to each 'dial knob', then you can rotate the knob under MCU control. You may also need a 'home' switch to put the knob in a known position at start up. One of the existing switch contacts may have a signal that can be used for this purpose (eg. power on switch).

How far can the LCD be lifted off the PCB?

Most meters use a conductive rubber strip to connect the LCD to the board. To extend this you would have to provide another circuit board to clamp the LCD screen and strip onto, then join this to the meter PCB with a ribbon cable. LCD drive signals are relatively low frequency and very low power, so the cable could probably be made quite long.


I would advise against attempting this for the following reasons:

  • Difficulty: soldering onto the switch tracks will be messy and multiple poles will be required - up to six according to your photos.
  • Isolation: you haven't stated this in your requirements but if, for example, the meters are not using a common "common" then relays have to be used. Direct micro control would not be possible.

enter image description here

Figure 1. Multimeter LCDs are frequently connected to the PCBs by zebra strips. From FujiPoly: ZEBRA® connectors are composed of alternating layers of conductive and non-conductive silicone rubber. Contact density of the ZEBRA® connector is greater than the contact pad density of either the LCD or PC board, making it an ideal design choice. When placed between the LCD and PC board at least one conductive layer will connect matched contact pads and at least one insulating layer will isolate adjacent circuits.

  • If the LCDs are connected by zebra connectors you will not be able to reuse the LCDs without a purpose-made remote PCB.

Alternate suggestion:

Again, you haven't specified what readings you want to take (voltage, current or resistance) but all the multimeter functions can be recreated with a dedicated panel meter.

enter image description here

Figure 2. A typical 0 - 200 mV LCD voltmeter.

Using multiple standard 0 - 200 mV DC meters may be a better method.

  • These are cheap (but watch out for cheap units with poor linearity and calibration).
  • They are fully isolated (provided you don't try to share the battery between all the meters).
  • Will run for an age on a 9 V battery (1 each to ensure isolation).
  • Have bezels so that your panel won't look a mess.

For voltage measurement you add potential dividers. For current measurement you add shunts. The units have switchable decimal point positions and V, A, Ω, DC and AC symbols.

enter image description here

Figure 3. A typical LCD pinout. (This one doesn't have units symbols.)


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