If you check the narration discs for filmstrips, you will find that many
of them had an audible cue tone on one side for manual machines, with
the other side having a sub-audible tone (50 hz?) for automatic

Mike Biel  [log in to unmask]

-------- Original Message --------
Subject: Re: [ARSCLIST] voca-film technology
From: Steven Smolian <[log in to unmask]>
Date: Thu, August 02, 2012 10:03 am
To: [log in to unmask]

I seem to recall that the auto-slide feature, at least for the general
public, arrived c. 1960. I remember the big too-doo about the Kodak
multi-slide exhibit at Grand Cenral just before the 1963-4 World's Fair.
When I worked there, I recall assembling shows for clients and adding
triggering beep which had to be at a certain frequencey. It went onto
"B" channel of a 2 track stereo tape. 

I think many transcription houses had switched to 12" discs, especially
the classroom market, as that's what I remember being the size player
the film- record player machines of that era. 

If anyone really cares, a look through the audio and educational audio
supply books of the period will have an answer.

Steve Smolian

-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:[log in to unmask]] On Behalf Of Art Shifrin
Sent: Thursday, August 02, 2012 7:52 AM
To: [log in to unmask]
Subject: [ARSCLIST] voca-film technology

Does anyone on this list know if the disks' tones were simply cues for
operator to advance the slides, and or, if a frequency-tuned circuit
triggered the next slide?