I recently -repaired a VERY damaged- coil meter that I scrapped from somewhere sometime in my life. I had this stacked in a box forever.
Now is working very nicely. Originally was sensitive between 2-10mA but after I repair it, is about ~30mA sensible. I had to recalibrate the shoyk out of it to make it functional and without needle bumping or dragging or touching. The tiny spiral springy watch coil(s), 2 on each side, they were the calibration element. It took me 1 day literally to concentrate only on it to put it on its feet. I also had to reconstruct (from melted plastic) a very important structural element that shattered in many pieces. Its made from a very nasty fragile aluminium alloy that crumble. This structural element was holding 1 springy coil and a very tiny axel. ETC-ETC-ETC... you get the idea. It was VERY bad.
Im very happy it is working very good now.
- All I need is a VERY NICE project idea to integrate this into. Well, actually many ideas if possible, a little brainstorm and then I want to pick the most cool idea.

Thank you !

 

I have some ideas that all rely on a smartphone to monitor internet-available data.

Where I live I have variable electricity pricing. The price changes hourly. They provide an estimate that changes every 5 minutes or so. I've developed an app that switches things - in particular the A/C - depending on the electric rate. If I had an EV to charge I would certainly take advantage.

Anyway, it would be cool to have a standalone meter that would report the prevailing electricity price at all times. Should I run the dishwasher now or put it on delay? A quick glance at the meter and you'd have the answer.

Probability of rain might be another thing to monitor. Or a stock price.

I'm not sure how you'd do it, but total household electricity consumption would be cool. Like seeing how fast the meter is spinning.

 

Like seeing how fast the meter is spinning.

It's actually a needle that goes from 0 to 10 when is current loaded (~30mA) and when no current is present, the old mechanic clock spring inside it will drag the needle back to 0. That scale I made it on a piece of cardboard, originally there was something else, another scale and it was in the way of the needle, you could barely see it move it. I put a blob of melted white plastic on the tip of the needle to actually see it. I hope now is more clear.

Is this kind of mechanism inside:

 

OK, so scale it so that 10 indicates 200A or whatever the max current to your house might be.

 

Exactly;
A “10” would mean 100% of the quantity you are monitoring.

EDIT; a big applause for the restoration

 

Who in their right mind would place a kludged ammeter in line with their electric utility supply line?

 

taking things apart is a great learning experience. but i have to agree. using this in anything but toying around is making no sense.
there is an abundance of analog meters out there, with clear lens, properly marked scale etc,

 

OK, so scale it so that 10 indicates 200A

no, #10 means that 30mA maximum. The numbers in between is current from 0 up to 30mA. Actually at 10mA is still staying on 0 and then it starting to visibly increase/move the needle. I can change that carboard markings any time, but first to find a nice project for it.

taking things apart is a great learning experience. but i have to agree. using this in anything but toying around is making no sense.
there is an abundance of analog meters out there, with clear lens, properly marked scale etc,

I know. But I have this for free and now is also working. Let's find a nice purpose for it.
I was thinking to a clock, with a 32kHz quartz to beat 1/sec and the needle to increase by one tick per scale for each clock second. And then reset to 0 when is at max travel and start increasing again. Or, when is at the max end, to decrease with one scale tick per clock second.
Very nice idea, yes? No real purpose for it, just as a toy. But this is the kind of projects I am pointing towards with this device. Ideally a project with a nice clear and practical purpose, but a toy is fine too.
So, more ideas - brainstorm. Any silly, weird, impractical, whatever it is, just put it on the table here.

 

Who in their right mind would place a kludged ammeter in line with their electric utility supply line?

That's not remotely what I was suggesting!

no, #10 means that 30mA maximum. The numbers in between is current from 0 up to 30mA.

Sense >> Signal condition >> Convert signal to 10-30mA. (very similar to a standard 4-20mA)
The sense might be a copper wire loop or two around the incoming main. Conditioning would be rectifying and filter so that the AC signal becomes a DC voltage. The conversion could be an op-amp circuit to scale and convert the input voltage to an output current.

I'm certain this has been done before. I'd look to find an existing solution.

 

I'm certain this has been done before. I'd look to find an existing solution.

or quick sketch one - searching for one is also good. But Im still not getting your point 100%.
Again, and more detailed, what is your device do? Measuring current when is fluctuating from the mains? I dont think I have this kind of fluctuations in my side. Or I didnt understood your idea fully.
Thanks.

 

I have another idea. You know those 'follow the light' type of circuits? Facebook and youtube are full of them.
The needle will follow the light, basically. Cool, eh? Heh.

 

That's not remotely what I was suggesting!


Sense >> Signal condition >> Convert signal to 10-30mA. (very similar to a standard 4-20mA)
The sense might be a copper wire loop or two around the incoming main. Conditioning would be rectifying and filter so that the AC signal becomes a DC voltage. The conversion could be an op-amp circuit to scale and convert the input voltage to an output current.

I'm certain this has been done before. I'd look to find an existing solution.

It's good you clarified that.

 

Or I didn't understood your idea fully.

I described what is essentially a DIY clamp ammeter. You could use it on an appliance or on your whole house. You'd probably use a modification of existing circuits for driving a 4-20mA current loop since your meter appears to need a 10-30mA drive to go from zero to full scale.

 

Who in their right mind would place a kludged ammeter in line with their electric utility supply line?

No-one. They would use a shunt.

 

What the heck is a shunt?

 

What the heck is a shunt?

https://uk.rs-online.com/web/content/discovery/ideas-and-advice/shunt-resistors-guide

https://uk.farnell.com/bourns/rsn-3..._l8WEXdSQObcayM-2Yq42xJkazTzVs8YaAiywEALw_wcB

 

Seriously

I know you guys think I'm stupid, but I'm not that stupid.

 

What ever you decide to use it for, make it a static device. When you put the white blob on the pointer, you unbalanced the whole movement, so the needle position will depend on the attitude of the meter. you can correct that by adjusting the rear counter weight.
The scale will be much more readable if you replace it with a curved one that fits the arc of the pointer (as in the original).

 

When you put the white blob on the pointer, you unbalanced the whole movement, so the needle position will depend on the attitude of the meter.

This is very true, and I suggest you remove the blob of glue and instead very carefully(!) stick a triangle of shiny aluminium foil instead - it needs to weigh almost nothing.

 

it might be nice to use it for an atmosphere monitoring display. Use one of the kit boards from sparkfun or adafruit that monitor air quality (there are a number of metrics and there are a number of boards to detect each metric) and you could have a little readout on say pollen count or carbon monoxide. Hell or barometric pressure. There are a lot of ideas that could work.