Add an On-Off Switch to your Talking Timer

by Miami Mike, 02/05/2012.

This project was originally described on RCGroups.com in this thread . Revisions have been made since then and are still ongoing, so please refer to this web page for the latest information.

Talking Timers similar to this one are very popular down here in Florida. We use them in our thermal duration contests and for practice. They're available from several sources for as little as $15 or so.

One problem I've had with mine is that there's no easy way to turn it off. The battery drain is very low, but if you leave it running long enough you'll find the batteries dead when you need it for a contest. Over the years I've learned to remove the batteries between contests so that they'll last longer, but I came up with an alternative. It's a modification that doesn't take very long to do.

The timer has a switch at the lower-left labeled "REPEAT", with selections labeled "YES" and "NO." With "YES" selected, as soon as the timer counts down to zero it starts over again at the previous start time. I figure the feature is meant for cooking when you have to stir the pot at regular intervals, or something like that. At any rate, I haven't found it very useful for our purposes so I turned it into an on-off switch. Now, selecting "YES" turns the timer on and "NO" turns it off.

To do this modification you'll need a small jeweler's Philips screwdriver, a few inches of wire-wrapping wire, wire strippers, an Exacto knife, and soldering equipment. You might also want to start out with new batteries so that you'll (probably) never need to change them again.

Step 1 - Open the case.

Remove the battery cover and batteries, then remove the four screws and open the case while the front is facing downward, being careful not to break the speaker wires.

Examine the bottom of the PC board, then scroll down to Step 5 and make sure it looks like one of the two types shown there. If it does then proceed to Step 2. If not, you have a type that I haven't seen yet and these instructions won't work for you.

Step 2 - Remove the 5 screws holding the PC board.

Step 3 - Carefully remove the PC board.

Gently pry the small PC board on the side of the main board loose from its plastic slot, being careful not to flex the solder connections to the main board, and then remove the board assembly. Set it next to the bottom half of the case so that you don't have to disconnect the speaker wires.

Step 4 - Set the top of the case aside.

If the rubber membrane sticks to the top of the PC board, peel it loose and put it back inside the top half of the case in the correct position. Notice that in the picture, the membrane is backward. The corner notch belongs against the edge of the case.

Keep all of the plastic pieces and the glass display with its foam strip in their proper positions inside the top half of the case, and set it aside.

Step 5 - Identify the type of PC board you have.

So far, I've encountered two types of PC boards, which I call "Type A" and "Type B." My guess is that Type A is the most common and Type B is a copy of Type A. You can tell them apart by listening to the speech. (Type A has better sound quality.) To continue, examine the pictures below and click on the type of PC board that you have.

Talking Timer PC Board, Type A

Talking Timer PC Board, Type B

To continue, click on the type of PC board that you have.

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