This is a vintage ammeter I picked up at a flea market over the summer. I had this idea to make it into a night light for the hallway outside my bedroom.
This is the back side.
When taken apart you can see it has a lot of area inside, or at least it will have when I remove the components.
This is the inside of the top with everything removed. I decided to remove all the brass pins on the surface that were used to mount the internals and the dial face.
I then drilled and tapped the brass plugs that were left from the pins so I could remount the dial face again only deeper inside the lens and bezel.
Because there was a third brass plug left at the top I added another 4-40 brass mounting screw to this location.
This is the meter with the dial face remounted in its new lower position.
Meter with the lens and bezel set back in place. Now I have enough space to add a high brightness neon bulb inside at the bottom of the face. The neon will light up the face and reflect nicely outward. I chose a neon bulb for a bunch of reasons. They run off of mains power (120VAC), they draw very little current (~1.3mA), they last a long time and they look really vintage.
So now I need to get power into my light. After mulling several ideas I came up with using the plastic back of a wall plug in transformer.
I took it apart and trimmed it down so that it would fit inside the meter housing.
Next I notched the brass plate from the back of the meter to fit around the raised plug area of the plastic transformer plate.
Then I drilled three holes to allow the plastic plug plate to be securely attached to the brass meter back. The plastic was also drilled to allow the mounting screw for the brass plate to go through the plastic.
The meter is now ready to be wired with a neon bulb. Unfortunately I did not have any neon bulbs in stock so I ordered some along with a small 125VAC toggle switch that will also be mounted on the light. Got these from Digikey an electronic parts supplier.These should be here Monday so until then I cannot complete the night light.
This is the switch and neon bulb I purchased from Digikey. The bulb also needed a 33K ohm 1/4 watt resistor wired in series with it in order to get the proper voltage to the bulb. The bulb runs on about 90VAC.
The housing was drilled and milled on one side to accept the toggle switch and retaining screw.
Here the switch is mounted.
The leads for the neon bulb were inserted through existing holes.
Everything was soldered together.
Then the light and switch were tested.
The face was put back on.
The lens cover was reattached.
When tested the brightness was too dim with just one bulb. The switch is rated for 3 amps. The current draw of the neon bulbs is so is only 1.2mA, that’s 0.012A so the switch can handle something like 250 neon bulbs in parallel.
So I added two more bulbs. Each with its 33k ohm drop down resistor.
One in the dark.
Finally one with the switch off.