I see lots of displays for sale, it looks like I could just buy one and it’s all good to go, but there’s a few problems I have:
I need one that has x.xx voltage. All the ones I find only read to xx.x voltage.
I need to use external power, it can’t draw from what it’s reading as that’d be really screwy since those volts are going to the CPU and VRIN.
Voltage range of 1v to 3v. If you want me to be more specific, than .1v-1v to 1.7v (the lower min the better but i could live with a min of 1.3) and another at 1.8v to 2.6v.
Blue text (red is acceptable). 7-segment or LCD Blue negative (or red) i believe is what I have in mind.
That’s all. I’ve considered just buying a DMM and just ripping it apart but… yea, hopefully I can avoid that.
Specifically, i’d like to solder it to my CPU Vcore and CPU VRIN points. I know I’ve talked about reading software/mobo readings in a similiar mod, but this needs to be hardware level and thus I can’t use an arduino for this (or I could, but either way the data needs to come from these voltage read points. only other choice would be reading from the back of the phases but that’s basically same thing…).
Thanks. I’m hoping this is an easy answer and just a simple “yea buy this off ebay, this guy just isn’t listing all the info but we know this is the right thing” or "buy X parts and put it together’.
Sorry. Voltage range would be 1v to 3v. I can be more specific if necessary. I plan to just mount them inside my pc (which has a window) right next to the coltage read points on the mobo. Id use the psu’s 5v or 12v but I can use batteries too.
What other surplus electronics outlets? I dont see anything on adafruit or sparkfun.
I’d prefer something in blue (i could live with red). Either in 7-segment or blue/red lettering (i believe it’s called red negative, or blue negative).
lyndon:
[Here! $1.90, can’t beat that price![/quote]
Yes, this is exactly what I am finding only, and what I referenced. Like I say in the title and OP, I need one with .01 resolution, not .1 (ie x.xx instead of xx.x). That voltmeter also has a useless range. I need ~1-2v at least (ideally 0-3v but I could buy 2 different ones or I can sacrifice and just get one with 1.4-1.6v and one at 2-3v).
It also needs to use external power, which I’m not sure that one can do. The red text on that 7-seg is fine, i’d prefer blue, there are blue ones like the one you linked.
This is specically for CPU Vcore and CPU Vrin on haswell, so I’m watching my cpu’s true voltage at ~1.4-1.6v range (high overclock, extremely dangerous burn-out voltages) and VRIN ~2.5).
Did you search for “panel meter” with google? Lots and lots of hits.
No, I haven’t, I didn’t know what this thing is called. I just searched voltage display. But I have now searched ‘panel meter’ and found nothing that meets my classification.
It’s got the Arduino bootloader installed so it can be reprogrammed like the Trinket, in your case to use one of the 2 analog inputs to be a DVM. With a 10 bit ADC that’s ~0.005v resolution when powered from 5v.
Yes you’d have to add the analogRead(pin#) and mod the existing code to scale and display the ADC reading. Should be easy. IIRC SF had another ‘serial display’, almost exactly the same, that had code to put it in a “DVM” mode. You might see if they still sell it.
FWIW I saw a number of digital panel meters via Google, I didn’t search hard for blue 4 digit ones. I did see this. Perhaps they make a blue one ?
Just going to get a quick confirm here that this is what I’m looking for:
.01 resolution (that is, goes to the X.XX spot, ie 1.52v, 1.51v).
0-2.6v range at least
Runs off it’s own power instead of source’s power
Blue Text
Refresh rate: about 300mS / times;
Measure Range: DC 0-3.300V
Display Color: Blue
Input Polarity: DC voltage;
Overload: 4 times range;
Input impedance: 100Kohm;
Display: 4 digit 0.36" LED Tube
Accuracy: 0.002V
Power Supply: DC7-28V;
Operating temperature: -40 ℃ -85 ℃
Dimensions: 40.5mm x 24mm x 17.5mm
Cutting Size: 37.5mm x 21mm
Anti-reverse protection, Overrange display 0
So AC range, check. Blue, check. Resolution, check. I’m not sure on the dedicated power supply thing though. I see power supply DC7-28v, so I hope I can just hook these up to the 12v rails on my computer’s PSU? They only need to be on when PC is on, as it’s measuring CPU voltage and CPU VRIN voltage.
On a side note, dat hot glue… I’m going to ask them if they can send it to me in pieces or without that part stuck on, because getting it out of that hot glue is gong to be really messy time with heat gun…
Belial88:
DC7-28v, so I hope I can just hook these up to the 12v rails on my computer’s PSU? They only need to be on when PC is on, as it’s measuring CPU voltage and CPU VRIN voltage.
Ah, they won’t send it unassembled. It’s okay, but let me look around a bit first.
I assume the wiring is Measure → (+) of measured thing, Voltage line to power, and then for black… you splice it into 2 lines and one goes to power,one goes to (-) of what you measure. And if you were to use the power of what you measure, you would juts go black/measure to (-)/(+) of what you were measuring and leave red off.
I found this, searching for ‘4 digit voltmeters’ that have a minimum voltage of 0:
Guise, this is going to look SO awesome… i will provide pics ^^
I got a question about wiring - say I did want to use the source for power, would I attach green and red wires (measure/(+)) or just leave measure hanging?
I’m kinda interested in having one of these on my car battery, just like an alert for if it goes too low so I stop running out of battery. Would be really cool to have it alarm if it hits a certain voltage point. I guess that’d be a mod for a trinket…
So googling “4 digit voltmeter blue” and ones with 3 wires and no big components on the back is what I need to be looking for (3 1/2 never have low enough minimum range, and 5 is expensive needlessly and ugly)
I think I’m going to go with this one. Cheaper than aboves and no mess of hot glue I have to burn through. It’s got a higher max range so I’m guessing it’s more inaccurate (despite same official spec) but w/e, this is more novelty and 3 digits is really as much accuracy as I need.
Accuracy is typically specified as a percentage of full range so 0.3% of 33V is 0.11V, + 1 digit at that range, let’s say it’s on a .01 V resolution, would be 0.12V accuracy.
Oh wow, I wouldn’t have figured that. So basically I want to get the voltmeter with the lowest maximum range. Which means either tha 30v one I just picked, or the 3.3v one earlier that I had to clear out all the gunk from.
I messaged the sellers and they said they couldnt sell it separate, ill email them again saying my purchase is contingent on it. Or maybe I’ll see if I can findvit sold separately elsewhere.
yea but i can’t have it say 1.5v when its really 1.6v. saying 1.55v when it’s 1.6 isn’t really good either. Acceptable woul be like 1.58v when it’s 1.6v maybe.
So I’ll have to find one with either high accuracy or ~3v max.
I think I’m going to abandon this project at the moment, I got the info I needed to do this in the future (like for a car or another pc, very cool stuff). I’m going to continue this topic over at : https://forum.sparkfun.com/viewtopic.php?f=42&t=36671
Where I think I’ll combine my cpu temps display mod with this one. Even though I want to use different inputs for temps(software) and voltages (hardware), maybe a MCU can display these inputs on the same display.
