Picture of Build an Analog Electricity Usage Meter
wiring .jpg
I have used a Kill A Watt (http://www.p3international.com/products/special/P4400/P4400-CE.html)  electric meter for a while and I decided to build  an analog one. This project went from being simple, with a single panel ammeter and an outlet, to full scale with three meters, a lamp socket, binding posts, and switches for all the outputs.
I also decided to pay attention to the aesthetics of this project and build one that had a steam punk look.
Rather than simply mount the plastic meters I decided to remove the movements and reassemble them in a wooden case and make my own numbers for the meters with a piece of tea-stained paper and an old typewritter.

From Simple to Complex
The basic design requires only 4 components. A cord, an outlet, a volt meter, and an ammeter. My design is more complex because I have two ammeters and three outputs, each with an independent switch.
Volt meters are connected across, where the current travels and ammeters are connected through the path of the current. (See picture two)
The idea of using a steam punk aesthetic meant that the plastic gauges with pre-printed backgrounds would not work. Thus it was necessary to disassemble each one and rebuild it in the new case. Avoiding this step and mounting the panel meters intact will save a considerable amount of time.

Other Design Ideas
One idea is to use an economy multi meter, often available for under $10. It would not be difficult to build a small case, add a plug or a cord and an outlet, and wire the system together. This would be considerably simpler and less expensive.
One important consideration is that to measure volatge you must connect the meter across and to measure amperage you must connect it through.

Measuring Wattage
Measuring wattage directly requires expensive laboratory equiptment. Since W = V*A most devices measure voltage and amperage and multply them together. One idea would be to have the needles of a volt meter and ammeter overlap. The wattage could be read at the point where the needles cross.
The simplest answer is simply to have a multiplication chart with the rows being 110, 115, 120, and 125 for the volts and columes of 1-15 for the amps.

ScubaSteve5 years ago
can you make one that measures from 10-15 volts?
static5 years ago
Allied Electronics carries 3.5" round meters but you would have to spend nearly $200 to duplicate what you have here. Wrapping the  clear meter face cover in a  flush fitting bezel would clean up the appearance a lot. devising a slide rule like apparatus to calculate the power, mounting it in that unused space near the bottom may give it a more of an old tech appearance.   In the event you decide to add a bezel semicircular tops over the scales would add to the old timey look. Man that wide carriage typewriter looks bizarre, I guess there was need for landscape printing way back.
pribich (author)  static5 years ago
In my searching I did find a few options for circular meters, but as you mention the cost is very high. I have given some thought to making a grid for power. It would use 3 rows for voltage 110, 115, and 120 because that would be the voltage range that would cover most AC outlets in the US.
Do you have any thoughts on the best way to make the bezels?
BadMonkey635 years ago
Really cool!!!!!
Went and got all of the components and going to build now!!!!! Keep it up !!!
pribich (author)  BadMonkey635 years ago
Thanks. I can't wait to hear more. Keep me posted.
I love the typewritten meter labels - It looks like something from the museum of mad scientists!  :-) 
pribich (author)  Trigger_Happy5 years ago
I am glad you like it. That's the exact aesthetic I was going for.
Re-design5 years ago
Hey, I've got that same table saw.  I filled the gaps in the cast iron table with fiber glass reinforced bondo and sanded it down flush.  Now I don't pinch my fingers in the hole when I move the fence.
pribich (author)  Re-design5 years ago
Intersting thought. I assume that you are talking about the large rectulanger gaps and not the T-slots. They haven't given me too much trouble but if they do I know what to do.
Absolutely the gaps in the table not  the t-slots.  I know what the t-slots are for.  The gaps in the table I assume are for lessoning the weight of the table and to use less stee.  They are just a the right spot for me to rest my hand when I'm moving the fence or on the other side moving a piece of wood and had caught my thumb or finger several times and got really tired of doing that and fixed my table.
aaon Re-design5 years ago
Those gaps are for attachments to the table saw. However, to each his/her own.
Re-design aaon5 years ago
What can you attach using them?  Maybe I'm missing out on something that I don't know about.  I can always use a new tool or accessory.
aaon Re-design5 years ago
I have made a bunch of custom ones myself: holding formica down so it doesn't chip, cutting angles other than straight cuts, material holders. However, I own a delta. Google returns tons of "table saw" accessories.
DougBishop5 years ago
beautiful project just an old mans thought When you attach a wire to a mount tab with a screw, like on a switch, you should twist the wire together and solder the end with just enough solder to "tin" the end and hold all the strands together. This will prevent a loose strand from straying into a position where it should not go, the possibility of the magic smoke being released from the wires is greatly reduced.
pribich (author)  DougBishop5 years ago
That's an excelent thought. In some of the tight areas, such as the connectors on the meters I did tin the wires with a bit of solder. I also always twist the strands tightly and wrap the wire clockwise so it binds together when I tighten down the screw or nut.
z0rb5 years ago
 You might want to factor in the formula of W = V * I * Cosign of the phase angle of your resistive to inductive loads. That will give you a true power figure for AC circuits. :D
pribich (author)  z0rb5 years ago
Intersting idea. So far I have only used it for basic measurements and making solid estimates of power consumption of various appliances. But you are right it will be important if I want more accurate information about AC circuts.
kmpres5 years ago
I'd wager your typewriter is worth much more than your project, though I like your project, too.  Well done, and with a taste for style.  A few tips: If you use good 60/40 rosin core solder and not too much heat on the heat-shrink sleeves you'll make better connections without burning the insulation.  Sanding the corrosion off the wire ends before soldering helps too, especially on salvaged wire. 

Have you thought of using 270 deg meters like those used in the 1950s sci-fi classic, Forbidden Planet?  I'd love to get my hands on a few of those.  You could combine your salavaged dials with the 50s sci-fi flashing lights --- sort of retro-future steam punk... 
pribich (author)  kmpres5 years ago
When I first conceved this project I did a lot of searching for round meters. When I had trouble finding something I decided to go with the option of rebuilding inexpensive plastic ones.

Thanks for the solder advice. If you have any leads on fancy meters let me know.
KronoNaut5 years ago
I like this very much. 
One safety thing:  Since the binding posts are hooked up to 120 volts, I would make a removable cover for them.  Even with them being switched, there is the off chance of brushing against them when they are switched on.
pribich (author)  KronoNaut5 years ago
Makes sense. I wouldn't be too hard to make a small box with a hinge. In this design it would make the most sense to have the hinge on the right as it has the most clearence.
knife1415 years ago
Nice project.  Well executed, and it has nice style.  I REALLY LIKE your wide carriage typewriter!!
pribich (author)  knife1415 years ago
Thanks for your kind words. The typewriter is one of my favorites. I'm always looking for an excuse to bust it out.