worlds first PHASER (EMI) turns 68

[puretube]

it was a 1-stage anti phase-distortion unit  :shock:
http://l2.espacenet.com/espacenet/bnsviewer?CY=de&LG=de&DB=EPD&PN=US2178012&ID=US+++2178012A1+I+

[JimRayden]

Can anyone give the poor thing a birthday gift and figure out its values?

I think I'd build it someday if it's any good.  

------------
Jimbo

[puretube]

that`s the problem with you (meant in general  )  young folks...
schemos for nothing, CLICKs for free:

http://l2.espacenet.com/espacenet/bnsviewer?CY=gb&LG=gb&DB=EPD&PN=US2178012&ID=US+++2178012A1+I+

(I found the english version - now click on the next page button, so you can read the values...)

[JimRayden]

Thanks.

The following question remains: what the hell does an anti-phase-distortion do?

--------------
Jimbo

[Transmogrifox]

That's a big question:

The simple answer is, it's an all-pass filter with a particular phase response designed to negate the effects of a system with an unwanted phase response.

When sending television or other electrical signals through long transmission lines, there is a nonlinear phase transfer that messes up the time relationship of the different frequencies in the signal.  This is called "phase distortion".  So you design a circuit with a phase response that brings all of the frequencies back into the same phase relationship.

A phaser, as a guitar effect is one of these circuits with a phase response that can be modulated (without variable capacitors such as the circuit of this thread, instead generally variable resistors ).  Furthermore, the phase distorted signal is mixed back into the "dry" uneffected signal to create a notch filter.  The notch caused by a null on the frequencies shifted by multiples of 180 degrees, thus a notch filter.  The more stages you add to a phaser, the more phase shift you get, thus you get more notches.  When you increase the resonance, the notches get more narrow.

You can use this method to generate Bessel filters and other interesting elliptical filters if done correctly.