Adjusting ringer bells

Ericsson DE100 Ringer
Ericsson DE100 Ringer

A well-adjusted ringer has a very nice after chime. It zings for a while after the hammer (officially clapper) has struck the gong. The questions is of course how to adjust them, so that they have a nice chime.

So I wrote this simple how to to help you along adjusting your ringer.

Lay out

This is a picture of the most common kind of ringer. It is an AC ringer (alternating current), with 2 gongs. There are other kinds of ringers, with one gong for example or concentric gongs, or only one coil.

Ringer ingredients
Ringer ingredients
  1. gongs, bells. North American telephones usually have gongs with the same frequency, European phones often have different notes giving a harmonic chime.
  2. coils, basically electro magnets. The alternating current reverses their magnetic field frequently resulting in the clapper moving to and fro.
  3. hammer, officially clapper. It moves from side to side, striking the gongs. At least it does that when it is adjusted well.

The hole is not in the middle

The screw is not in the middle of the gong
The screw is not in the middle of the gong

Eccentric is the official term for it, although it is hard to tell by looking at it. This is makes it possible to adjust the bells so they sound right. A badly adjusted ringer sounds more like a buzzer, because the hammer dampens the chime or because the clapper does not hit the gong at all.
If you turn the gong, you gang adjust it so that it gives that perfect sound.

Please note that some ringers have adjustment screws or other means to tune it.

The right distance

space between gong and clapper
space between gong and clapper

The right distance between the head of the clapper and the rim of the gong is about 0.5-1 mm. That is because when the clapper is activated and it swings toward the gong, it will bend a little because of its momentum and just hits the gong before it springs back. So it give a short but definite hit.

Here is the sound of a ringer where the clapper does not reach the bells. The distance between the full deflection of the clapper and the rim of the gong is too great.

Here is the sound of a ringer where the distance between is too small. The hammer hits the rim for too long and dampens the chime.

So the distance between the clapper and the rim of the bell is very important. It needs to be very small. See picture

Now: find the right screw driver!

Wrong screwdriver
Wrong screwdriver

Before we start adjusting, you need to get the right tool. In most cases you need a screwdriver. Often people use a screw driver that is too small. The blade is too narrow and it is not thick enough. This not only makes it harder to loosen and tighten the screw, it also nicks the slit in the screw. Often these screws are nickel plated brass, which is quite soft.

Right screwdriver
Right screwdriver

So make sure you get a screw driver that fits well. The blade must ideally have the same thickness as the slit in the screw and have the same width (or greater).

This makes the loosening and tightening of the screw a lot easier and above all prevents damage to the head.

So do not make me angry and



So the trick is to have a certain distance between clapper and gong. About 1 mm is usually enough. I judge it by eye, at first.

Piece of paper under the clapper
Piece of paper under the clapper

To begin adjusting, loosen the screw just enough so that you can turn the gong, but not too loose. Then fully deflect the clapper towards the gong you are adjusting. You can do this by pressing your finger against the back of the clapper. If there is not enough space, you can use a tool.

It helps if you slide a piece of white paper under the clapper, so you can see better what you are doing.

Please note that some ringers have a bias spring. This spring pulls the clapper always to one side, when it is not active. This spring prevents the ringer from unwanted tingling with noise and clicks on the telephone line. So you may need to keep your finger on the back of the clapper.

When the clapper is in the right position, turn the gong until the distance between the head of the clapper and the rim of the gong is to your satisfaction. Then tighten the screw.

Repeat the process for the other side.

You can test your adjustments by tapping the back of the clapper, thus activating it. Of course you need to do this for both sides. The gongs should sound and have an nice after chime. If the sound they make is short and dry, you need to increase the space between the clapper and gong.
If it is faint, you may need to decrease that space.

Before putting back the body shell, it is wise to try to make the phone ring on your telephone line, so you can make sure you like the result.


At first it may take you a couple of times to get the adjustment right. However, it is worthwhile to make the effort, as a correctly chiming ringer is quite a joy to hear.

Did you enjoy this article, do you have any questions or would you like to share your experiences, please leave a comment below.


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