Maestro FZ-1 Patent ~ Check it out

[pupil]

http://www.google.de/patents/US3213181?hl=de

I suppose this is nothing new, but it is a dead link on archived topics. They walk you through the circuit a little bit. Pretty sure they are wrong about the value of resistor 261. It is 470K.

I guess the highlight of what they claim as new is the inclusion of a "minimum of 25% harmonics"? Otherwise I don't see how the maestro is any different from an emitter follower into two common emitter clippers.

I know nothing about patents, but I get the feeling this one is no longer relevant. Just some here-say though.

[PRR]

Link to US patent, which is surely the original:
http://www.google.com/patents/US3213181
This link also allows downloading the whole PDF file.

> Pretty sure they are wrong about the value of resistor 261. It is 470K.

You leopard you!! (Well-spotted.) Yes, 470r makes no sense, 470K is a happy value.

> know nothing about patents, but I get the feeling this one is no longer relevant

A patent from 1962/1965 is surely expired.

And what you could infringe is not the *circuit* (as you say, it is nothing-special) but the too-extensive list of Claims, many of them redundant or overlapping well-known functions in Prior Art. *I Am Not A Patent Lawyer*, but seems-to-me that very trivial changes (like bypass switching) would evade the specific Claims.

In any case, you can build one "for study".

If you are planning mass-production, you want to review all the later patents. Someone may have come up with a slick-trick, which you might independently invent and use, leaving yourself open to an infringement claim. (Your Legal Department will know how to do such searches.)
_____________________________________________
FWIW: the patent cites “Transistorized Instrument Amplifier,” Popular Mechanics, November 1957, pages 160, 248 which can be found at:
http://books.google.com/books/about/Popular_Mechanics.html?id=oeEDAAAAMBAJ
extract-- http://i.imgur.com/zhhOR8a.gif
This has little to do with the patent. It is a super-early all-transistor instrument amplifier of about 1 Watt output. However it is emitter-follower input, then two CE stages. Maybe Snoddy and Hobbs liked the Gardner-amp sound, and wanted it in pedal-form to use with a more reasonable power final amplifier.

[pupil]

Ah, that's interesting. Maybe they were impressed with how hard that schematic was to read and made and even harder one to read ha!

Well of course it's not actually hard to ready; I'm just not used to seeing the voltage potentials being on the same side of the transistors.

Anyway, that's cool, thanks for sharing.

[PRR]

> not used to seeing the voltage potentials being on the same side...

That was Popular Electronics house-style. (OK, this was Popular Mechanics, but I think they had the same art director.)

I read through a couple decades of PE, and then some decades of Wireless World, and wonder just how badly the American Mind was stunted by PE's really awful schematic layouts. Stuff up here, over there. Like a house designed by an architect who hated his client.