Hammond Mechanical Phaser and Motor

[George Moore]

 I hope the images show up.
This came from a Hammond T500, it looks sort of like a generator, there are six connectors on the top, and the bottom, the short, medium and long yellow wires connect to pins surrounding the body of the unit, 1 is connected to 6, 2to5, 3to4, a few other wires that connect externally through that bundle.
  I dream to find a schematic which shows fairly simple peripheral components [bound to require a preamp, probably many R's and C's
  Judging from the two sets [top and bottom] of six nodes [radially located around the body], and that there is an offset drive pulley...my guess is this drives an internal gear to get slower rotation on a main shaft which sweeps the R/C phase stages and 'rest of circuit' on another board.
  My guess is either this unit did something unique [it's heavy, looks expensive, requires a pulley drive, etc.], or discrete phaser designs hadn't yet been discovered.

[anotherjim]

Search for Hammond Scanner Vibrato. It is an electro-mechanical phase shifter.
You don't appear to have the associated delay line box or multipole switch.
At the time of it's creation, the alternative would have been many triode tubes. No solid-state device existed.
The motor also drove the tonewheel generator.
Belt drive means different pulley sizes can be fitted to suit country AC supply frequency. The motor is synchronous meaning it's speed is fixed proportional to the AC supply frequency.
http://bentonelectronics.com/service-manual-the-hammond-vibrato/

[George Moore]

  Satisfying read, thanks Jim.
  To the Jfet and CA3080 type phasers.

[DavidRavenMoon]

http://modularsynthesis.com/modules/DJB-scanner/scanner.htm


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[Digital Larry]

I have a couple old Hammond tube amps that are waiting for me to stop messing with DSP and do something in the REAL world (i.e. convert them to Fender Deluxes or something like that).  I've read a lot of their service manuals and I am boggled by the complexity and electro-mechanical shenanigans and brute force approaches to getting things done.  By contrast, simulating everything in VHDL and making a chip seems almost quaint.

[ElectricDruid]

 Jean-Pierre Desrochers did a nice conversion of one of these Hammond organ scanner units. From his email to the SDIY list:

"Here is a short video showing the effect
of an electric guitar played through an Hammond organ scanner.
https://vimeo.com/221677362

The final effect is close to a Leslie effect (Mixed Chorus/vibrato)
including all the involved lags betweeen speed changes.
This personal project took me several months to accomplish..

You can see all the project files using the link below the video
including PIC C code, schematics and PCB layouts.
Enjoy !
J-Pierre,
ArcEnSon, Quebec Canada"

Tom

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[wkrbee]

A company had the vibrato scanner from a Hammond packaged to use as a guitar effect at NAMM in Jan.