Hi All.

I just acquired this little hearing aid and thought that it might be of interest to others.

It is 4 1/4" high and approx 2 1/2" wide. Considerably smaller than my mobile phone, and easily fits into my shirt pocket. It has three valves. 2x DF66, and 1x DL66, (2.5 mW at 10% distortion).

One source says it was introduced in 1948, another source shows an advertisement in 1950. Another source says one of the valves was released in 1951?

Anyway, I find it fascinating. Powered by a 22.5 volt battery, (like the one in my first multimeter), and an AA battery.

Wayne

Yours is the first one I have ever seen although was aware valve based hearing aids existed.

Remember reading a autobiography about someone in the 1920's and it was mentioned a person had a hearing aid in their pocket with a small headphone set.

Interesting devices and now an original one would be rather rare.

Similar story here... I certainly knew that valve hearing aids existed, but had never seen one. I notice the manufacturer had tiny white valve sockets fitted (well I guess they were white once). I would have thought the valves would have been soldered in, for a mobile device that would get its fair share of bumps.

I would have thought the valves would have been soldered in

The fact that they are socket-mounted may be a pointer to their expected life. I know that so-called "gassy" or "soft" miniature tubes had comparatively short lifetimes, although I don't think that these particular valves are in the soft category.

One thing these devices wouldn't have been is easy on batteries. But every idea has a starting point.

Looks like there was a production line in the US too:-

http://www.hearingaidmuseum.com/gallery/Vacuum%20Tube/Acousticon/info/acousticona120.htm

My grandfather was hard of hearing. Although he had a transistorised hearing aid, he mostly used to leave it off 'to save the battery' ... well, that's what he told my grandmother.

In the days before our wizz bang alkaline/lithion/nickelhydride batteries running one of those on a daily basis would have been an expensive exercise.

Would imagine a carbon zinc AA battery each day. Think even a modern alkaline AA would struggle to keep the filaments lit for the whole day.

Probably it was intended the device was only switched on when really needed.

Can anyone remember watching ' Fawlty Towers' with John Cleese?

If you have the series have a look at season 2 ep1 'Communication Problems' Mrs. Richards has one! other than that I've never seen them. What a nice find Labrat!

Audioaaron stole my thunder!!

Yes, I too was going to mention Mrs Richards who kept hers switched off "because it runs down the battery!! It drove Basil nuts!! I think hers was an "Amplion" in a brown bakelite case and she carried it at her waist. The case looked a bit thicker than this one, nice find though. Enjoy!!

I think hers was an "Amplion" in a brown bakelite case and she carried it at her waist.

Maybe Amplifon?

https://www.youtube.com/watch?v=tcliR8kAbzc

Well, it looked like it had a large "A" over the microphone opening, I thought of Amplion since they made loud speakers back in those days, but it could have another brand. Actually a small speaker would have made quite a good mic for that purpose. I remember my old "Philips EE20 Electronic Engineer kit from 1966 had a few projects where one of the speakers was used as a microphone!

I remember my old "Philips EE20 Electronic Engineer kit from 1966 had a few projects where one of the speakers was used as a microphone!

Intercoms use this principle.

I wal given a number of these as a kid in the early 60s. Wish I still had them.

Anyone else heard of a thing called a "Proximity Fuze"? They used hearing aid valves to implement a doppler radar in the head of an artillery shell. Amazing for 1940's technology. Changed the outcome of WW2.

https://en.wikipedia.org/wiki/Proximity_fuze

Prepare to be amazed....