Hearing Aid

Peto Scott Co. has sent to Wireless World two of their latest hearing aids, based on the design of the Wireless World model that was described in the spring of last year. Though fundamentally the circuit is the same as in the home constructor's model, sundry minor modifications have been introduced, and the layout has been altered to enable the set to be accommodated in a case measuring 6” x 5” x 4”.

In the Peto Scott version two Hivac midget valves are used, an XD for the first stage and an XP for the second stage. These two valves, which are transformer-coupled, give considerable amplification, and although the sensitivity is high there is no trace of microphony. Its response to severe shocks is minimised by mounting the microphone on sponge rubber.

 The two dry batteries, one of 45 volts and the other of 3 volts, for HT and LT respectively, are very accessible and quite easy to replace when the need. arises. The HT consumption is about 1.5 mA at normal volume and rises to just under 2 mA at full volume. The valves take 0.2 amp of filament current. These currents are well within the capacities of the batteries fitted.

Both models of this hearing aid are similar in size and in external appearance and differ only in one detail. One of the models has a tone control embodied, but as it is intended to be used only as a frequency corrector to compensate for individual deficiencies in hearing, the control knob is located inside the case. Complete with a single earpiece and headband the model, without tone controls, costs 6 guineas and the one with, 8 guineas.

See also the Wireless World home constructor's model.

Here you find 48 models, 34 with images and 16 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Peto Scott Co. Ltd. & British Radio Gramophone Co. Ltd.; London