I had some old glass door knobs that I thought would look really great lit up by an LED. So after a few tests, I came up with this idea. Kind of like a Wizard of Oz thing... The knobs light up with a variable changing color based on your body resistance.
The circuit that drives the RGB changing LEDs is the same transistor circuit used in the Touchy Pet found elsewhere here in Instructables.
Materials and Costs:
Edison bulb candelabra size $4 USD
DC ammeter - $15 USD eBay NOS
Toggle switches - $3.50
Dimmer control 120 VAC $6 USD
USB charger $1.50 eBay
Lamp cord $3.00 USD
Oak wood - $15 USD
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Since I didn't have a antique telephone box or similar electrical wood box, I had to build my own. After cutting the oak panels out, I took a propane tank and slightly burned a few areas of the panels which turned some of the open grain darker than the tight grain. I also beat bolt heads, screw threads and nail holes into the wood. These dents were then highlighted with some black and green paint, wood putty and re-sanded to look like the wood had been refinished several times.
For the ammeter, I opened it up and added a small RGB LED inside it as well to follow the lighting of the entire box.
The USB charging port for charging a phone or other device from the rear of the box, was opened up to tie in a white LED to back drop light up for finding the port more easily. I also tied in a "power on" led from the same circuit to indicate the USB charge was on or not as controlled by the front toggle switch.
To get the glass knobs off their shaft, I CAREFULLY had to cut through a brass collar that was crimped around each knob. I used a dremel cut off whell to do this by cutting ever so slowly through then using a pliers to pull the brass apart.
I used a phone power supply for the DC circuit and the Touchy circuit. Just cut open the case with a Dremel and be sure the resistor vales are right for the LEDs. In this case it was a 9 vdc charger.
This was perfect for the transistor circuit. It is shown here with copper ground wite for the contacts. I used a piece of plexiglass for the mother board mount to hold it all together. Then the plexiglass was screwed into the inside wall.
The glass knobs had two functions of LED lights in them. Basically two sets of different leds. Two 10 mm RGB non-changing for ambient lighting as selected by the selector switch (non dynamic for the touchy circuit) and then two 5mm rgb changing leds as driven by the touchy circuit. When the touchy circuit is completed by placing a finger across the contacts, the changing leds will flicker and change colors with the changing resistance. They were all assembled in one large assembly by sanding half of the leds down on a disk sander, then epoxying them together, then again epoxying the 5mm LEDs to the largey assembly. The entire led assemblage was siliconed into the bottom of the knobs.
Complete the wiring and be sure to use shrink tube or equivalent product to keep soldered joints from contacting each other and shorting. The box really got congested quickly. Use of ribbon wire also helps as does a terminal strip in the pbottom to minimize connections in line.
I also etched the copper control panel plates in the laser printer masking method and the solution of 1 part muriatic acid, 2 parts hydrogen peroxide solution, then painted them in. Safety precautions and details can be found elsewhere on the internet.
Lastly I used a shoelace to conceal the standard plastic lamp cord for a traditional look.