The most lame patent ever?

[dbanner]

Oh boy, what to say about this one.

Hats off to inventor. What a stroke of genius.
Hahahaha.

https://patents.google.com/patent/US4594559A/en

[Altra]

The good old days when you could patent 7 components. This patent was for the "Depthmaster" and they sold lots of them. Only $69.95

Here's a little info

http://www.treasurenet.com/forums/metal-detecting/97545-depthmaster-audiophone-ii-headphones.html

[Carl-NC]

The Depthmaster worked pretty well and were popular for a while. It was sold both as an in-line box for existing headphones (I have one) or as complete headphones. Yes, incredibly simple and probably not a worth a patent. The diode clamp was probably the key element that made it even slightly patentable.

[dbanner]

You have to love such things. $69.95. Wow! Patent office must have been short staffed in those days. That circuit isn't even remotely patentable. Diode or no diode.

The "depth master". Ooooh.... hahahaha!

[Ferric Toes]

The diode also protects the phones in the event of a reversed battery connection. You blow the transistor instead. Very clever

Eric.

[dbanner]

Very clever indeed.
$69 in 1984 is equivalent in purchasing power to about $170 in 2020. That's one incredibly expensive diode.

[Altra]

Pro's Agree, lol

[Peter Jones]

There's one on Fleabay at the moment, in Germany... You won't believe the asking price