Things You'll Need
Sharp knife/razor blade
When French chemist Georges Claude first began experimenting with newly discovered inert gasses like neon and argon, he likely had no idea his work would find such an enduring place in Americana. For good or ill, the neon sign has colored the American landscape for the better part of a century. They have also delighted collectors through the years, and many a finished basement are incomplete without at least one neon beer sign. The signs can be a little harsh and bright up close, however, so in order to get just the right ambiance around the basement pool table, a dimmable neon sign may be in order. It can be done.
Dimming a neon sign
Unplug your sign and move it far away from the outlet for good measure. Neon signs require low current and high voltage to work, so you don't want to make any mistakes. Transformers have an output range of 20mA to 30mA and between 3,000 and 15,000 volts.
Choose a transformer that matches the output connections of the one currently powering your sign. Slight differences shouldn't affect the operation of the sign, but a different transformer may have slightly different connections, so match it if you can. Never use an off-the-shelf lamp dimmer with a neon sign. They regulate voltage but not current, so you could end up damaging, destroying or setting fire to your sign.
Locate the connection between the neon tube and the transformer. Pull back the insulation. Heating the sleeve can help to loosen it enough to pull it away from the connection, but if it still won't budge, you can cut it away with a razor blade.
Unwind the wire from both connections to the glass tube. The wire is very delicate, so be careful not to break it off. You'll want all of the wire in good shape, should you decide to use the transformer again or sell it to someone in need.
Repeat step four with the wires at the switch. The transformer is the bridge between the switch and the tube, so everything should be centrally located and easy to reach.
Wind the wires from your new transformer to each of the open connections at the switch and the tube. Replace the insulation to protect the wires. Your new transformer should have a knob near the pull chain, so when the light is on, use the knob to set the desired brightness.