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Free Telephone Ring Indicator Plans

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That's free plans for a phone ring indicator, not plans on how to obtain a free phone ring indicator.

This page will describe how I built a phone ring indicator. This project is simply a neon bulb and a resistor (actually two resistors, to help tune the brightness versus current draw). They are encased in a translucent film canister.

DISCLAIMER: I built my ringdicator and it is working fine. However, I cannot oversee your work if you decide to use my plans, so I cannot guarantee that your ringdicator will not interfere with your phone service. Be careful when working with the phone lines as you can be shocked by the voltage on the lines, especially during a ring cycle. Remember to wear eye and ear protection while using power tools or working with wood or being around anything that is noisy or can shatter or can project small pieces of material.


Description Price Per Quantity Price Total
Small neon bulb 3.29 for 2 1 1.65
Telephone cord free 1 free
20k resistor 0.05 1 0.05
20k variable resistor 3.29 for 12 1 0.28
Translucent film canister free 1 free
Total Price for Materials (in US $) 1.98

Also needed:

  • Soldering iron
  • Solder
  • Wire stripper


I spent the following time on the project. Your mileage may vary.

  • 15 minutes gathering components
  • 5 minutes assembling them
Total Time: 0.3 hours.


Here are the steps that I used to make the Ringdicator.

  1. Finding the Components

    This is not a very complex step. Since some of the items were obtained rather than bought, I had to spend some time finding them. There is always an extra phone cord in the house somewhere, since they are so useful. I took the phone line that was packaged with the copier/scanner/fax machine, because we have no plans to use the fax part of it.


    The film canister was easy to find, as we go through rolls of film quite regularly.

    I had already bought everything else (resistors and neon bulbs) at one time or another, so they were readily available at my project desk.


    The longest part of the whole project involved a trip to the electronics parts store to buy the variable resistor. I had some lying around the house, but none was small enough (dimensionally, as opposed to resistively).

    You do not need a potentiometer (AKA variable resistor) for this project, but it helps. The resistance is needed to limit the current drawn by the neon bulb. Lower resistance means more current which means a brighter glow, but that also means fewer ringers can be connected. A too-low resistance can cause some not-so-good side effects, such as no other phones would ring. On the other hand, a higher resistance means less current which means a dim bulb. I included the potentiometer so that I could get the brightest glow possible without affecting the rest of the phones in the house.

  2. Connect the Parts

    First, I cut apart the phone cord. This works out well, because the neon bulbs are sold in pairs. So cutting the 6' phone cord in half provides one 3' cord per bulb. However, 3' is a little short; it would be more useful to have the full 6' of cord.

    Then, I placed everything together and soldered the connections. The resistor needs to be in series with the variable resistor so that the resistances add.

    I clipped the extra wire and then wrapped bare metal parts in electrical tape, to avoid shorting anything when it is packed into the film canister. I didn't bother taking a picture of that step.

    beginning assembly

    In order to have everything contained in the film canister, I needed to cut a slot in the canister for the cord. If you want a hole elsewhere, so as not to weaken the seal with the lid, then you'll need to plan ahead and possibly thread the cord through that hole before soldering anything to the cord.

    slot in film canister

    Last, I packed the assembly into the film canister.

    The light is not as bright as I would have liked. Perhaps a different color, such as orange, would appear brighter. Another option would be to use a 10k fixed resistor with a 30k variable resistor. I wanted the fixed resistor to be significant enough to prevent any sort of disaster, but maybe 20k was too high to allow full current.

    final assembly