hello! so im just figuring out a module atm. basically an offset/attenuator also with a built in single mode voltmeter, Im probably going to have to scale it. to fit in with the 5v analog reference voltage on the Arduino nano. I haven’t started yet. wondered if anyone had any luck with this before??
2 decimal place 4 digit voltmeter -12v to +12v I recon it would be a nice touch to sit on top of an offset knob and an attenuvert knob. all 3 in 1 module would be snazzy. voltmeter on Arduino nano to keep it cheap simple to code and modify. funky.
obviously will need to be offset and scaled itself. 2.5v would be 0 I guess. 5v on Arduino would show 12.00 and 0 would show -12.00.
im thinking to keep it simple the + and - signs will be separate LED’s behind the panel so it shines through, as to save extra seven segment displays.
I’ve seen a few around with the ornaments and crimes style screen but I just aint a fan of those sort of screens, nothing like a nice bright red 7segment hey! haha
what you recon??? ill get working on it sometime this week as I feel the need for it in my syndesizer
obviously dont give you - voltages, but very good!!! and cheap. maybe there is one with -. OR OR OR!!! make the module have 2 of them, seen as they are so cheap one for positive voltages and one for negative. then you can have it look like a back to the future style panel display with green and red haha. actually that could be quite a good idea!!! also would save people the faff with the Arduino.
Some of these voltage meters have only 2 leads. Those are to power them AND to measure the voltage with. So they do not have separate probe inputs. I got a few of them. They are usable for monitoring e.g. a power supply.
I hooked up a few to an arduino a few years ago to measure the load of my pc. They allowed me to see whether my sometimes non responsive pc was very busy or had crashed. Anyway, you can use a milli ampere meter and a series resistor, connect them to an arduino’s pwm output and use the arduino as AD-converter for either some input analog value connected to the arduino’s analog inputs, or some digital value via one of the gpio-ports OR via the usb-port. In my setup I had a python program querying the systemload every few seconds and print that to the serial port which was connected to the arduino. The nano would read this value and output a value to the meter. Worked like a charm. Maybe you could use part of this setup in your design?
So the meter was calibrated to show a load up to 5 of my linux server. The nano would start waving the dial after not having read a value from its port for more than 10 seconds which to me was a sign that the computer would possibly have crashed.
yeah those are cool! however do you know of any good source of them? like a universal one people can buy for the kits? also from a cosmetic standpoint I dunno. you need to glance at them for a few seconds to see what the reading is, with a 7 segment one you can see straight off what it is at a glance. but yeah interesting point I didnt think old school of meters
My source so far has been aliexpress. B.t.w. it should be possible to modify these things. If you take a look at this example (hover over one on the right to magnify it), you can clearly see the DC input being routed to the rest of the circuit. The IC on the right is the voltage converter (the 1733H chip), the ic on the left is the multiplexer and possibly there is a separate ADC somewhere or it is there. Anyway, this thing is fed by the voltage converter. Finding the connection to the IC directly from the DC-in or via some attenuation gives the ADC-input. Finding that and disconnecting it from the power and adding a external input to it must be possible.
I have been working on my own version CGS joystick . Not exactly the same project, but the principles might help with scaling the voltage. The reddit post I made someone was very helpful with a explanation of how the circuit works. I’ll have too check out those meters. They look pretty neat.
My Schematic:
What’s the thinking behind the max range trimmers? Shouldn’t they be around (or rather in series with) the joystick itself, rather than the offset trimmer?
With having only fixed resistors there I was only able to get +8v with -3v Range. I changed the the range knob too 100k and it allowed me too get +10v too -6v. So they only way I found was to adjust the Max +/- too +5 and -5 was too change the fixed resistors with pots. If you have any ideas too make it better. I would love to hear it.
If you connect the joystick potentiometers between +12 V and - 12 V you have the whole range of voltages at your disposal. Limiting that with some trim pots in series (one at the plus side, one at the minus side) makes that you can select whichever range of values you’d like to use in your circuit. And this would simplify your schematic quit a bit. B.t.w. you seem to have ‘Y AXIS CV Controller’ twice. The top one should probably be called ‘X AXIS CV Controller’.
Thanks for the naming must of missed that while duping. The more simple circuit you are talking about should work. But wouldn’t it drag the voltage down that could effect the tune isn’t that is the reason in the original schematic they used inverting-amplifiers for this application?
