Mother's Under-$30 Hearing Aid

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Mount the clarity control in a 5/8" hole toward the left-hand side of the top oh the case. Next, the earphone jack should be positioned toward the top of the left side panel. These two devices will be secured with washers and nuts, but go ahead and attach their wires before you snug them up.

The last external item to be attached to the case is the battery holder. Unfortunately, a Radio Shack 270-397 battery holder doesn't quite fit into that supplier's 270-221 case, so you'll have to modify the holder slightly. Begin by discarding the cover and removing the contacts by pulling them straight up. Then remove the sides of the holder by cutting along the edge with a hacksaw. If all goes well, the modified unit should slip right into the lower part of the case-leaving enough clearance for the battery contacts to be inserted between the case walls and the holder. Do any final trimming that's necessary, align the holder, and glue it to the bottom of the case.

Finally, solder the wires connecting the external parts to the circuit board, and nestle the board into the upper portion of the case. A few small drops of isocyanate glue (commonly called "super," "crazy," etc.), placed against the sidewall ribs, will secure the board. Finally, insert the batteries and replace the cover to complete your hearing aid.

HINTS ON USE

Using the hearing aid is as simple as plugging in the earphone and turning the unit on by rotating the clarity control. Proper adjustment of the control depends on several factors, not the least of which is the severity of your particular hearing problem. Background noises, air temperature, and your physical awareness will also make a difference. The best suggestion I can offer is to adjust the hearing aid to satisfy your immediate needsbeing aware that they may change from moment to moment.

If you find the aid isn't providing enough volume, you can increase its capability by switching RI from 1k ohms to 470 ohms. Doing this, unfortunately, will also introduce some sound distortion, but it shouldn't be ter ribly objectionable. Should the gain provided by this swap prove insufficient, I suggest that you see a hearing professional about a custom design.

See Your Doctor First

THE MOTHER EARTH NEWS neither states nor implies that it's qualified to give medical advice-only a licensed professional is allowed to do that. If you suspect that you have a hearing problem, see your doctor. Then, should your physician agree that an amplification device may help you, you might well want to consider saving several hundred dollars by building the hearing aid we've described here. Remember, though, no matter what kind of hearing aid you use, the device isn't intended to be a cure-all . . . each person's hearing impairment will respond differently to an amplifier.

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