Speed Compensating Tape Recorder

[codescott]

The cheap Japanese toy tape recorders available in the 1960's did *not* use capstan drive. Instead, the bases of the feed and take-up reels had a rubber ring on the outside. A motor contacted that ring to drive the play, record, rewind, and fast forward functions. Thus the speed of the tape across the head varied depending on the position in the tape and the slackness in the tape winding.

I am told that these recorders used a 10,000 Hz bias signal to record the audio on the tape. I want to design a device with a second head before the play head, that detects the 10,000 Hz signal bias on the tape and adjusts the tape speed so that the audio plays at the right speed as it passes the read head.

I realize that the quality of the recording playback will vary according to how much the original tape speed was at record time. But such a device would allow me to re-record old tapes in a consistent way.

Any ideas???

 

[Nigel Goodwin]

Are you sure the bias was that low?, and that they even used bias? - often cheap recorders only used DC bias and a permanent magnet erase head.

I would suggest amplifying the signal from the head, and seeing if it has 10KHz on it - you probably can't use the existing amplifer as it presumably removes the 10KHz?.

In any case, why are you wanting to do this?.

 

[codescott]

I can use the speed compensating tape recorder to play tapes created on the original toy recorder, and play those tapes without the audio "speed up" or "slow down". I will re-record the tapes in a standard way, perhaps even just mp3.

 

[RODALCO]

I second Nigels comment.

I had a small AIWA R2R with 7 or 8 cm Ø reels, many years ago.

The motor drove the take up reel via a rubber ring which was underneath the take up reel.
As the tape progressed, the diameter of coil of tape increased and the tape to head speed increased as well.
The erasing was done via a small magnet instead of a proper erasing head.

During play the magnet head moved away from the tape to avoid erasing the tape.

These recorders were cheap so i doubt it that a 10 khz signal was used.
Also these were used for voice as a cheap recording medium.

Just my $ 0.02 worth.