Phonograph Speed Reducer
Phonograph Speed Reducer
Long-play records are available for the vision-impaired to listen to books recorded by voice actors. Records recorded and played at half speed will play for double the normal time. This inexpensive speed reducer drops onto a normal 16-2/3 RPM record player, and plays 8–1/3 RPM talking-books.
How it works:
This adapter uses the concept of a Lazy-Susan found on dinner tables, or the glass plate in microwave ovens which rides around on three small wheels attached to a plastic ring which turns at half the speed of the glass plate.
Using a car tire as an example, the bottom of the tire is briefly motionless while in contact with the road. If the car is driven at 30 MPH, the top of the tire moves forward at 60 MPH (relative to the ground) in order to catch up and go around again. The important relationship is the 2:1 ratio between the top of the tire and the axle.
The speed reducer is made in three layers and drops onto the turntable like a phonograph record. The top and bottom layers are rigidly attached to each other through a clearance hole in the middle layer (shown in red below). The first time the speed reducer is used the protruding arm rotates until it comes in contact with an obstruction on the record player (ex.: the support for the tone arm).
The turntable rotates at 16-2/3 RPM. The axles of three small rubber wheels, are attached to the bottom plate. The weight of the record keeps the tops of the wheels in contact with the middle stationary layer (red), causing the wheels’ axles to move at 8-1/3 RPM, half of the speed of the 16-2/3 RPM turntable.
If the slowest speed on your recored player is 33-1/3 RPM, you can use two speed reducers, one on top of the other, to reduce the speed to 8-1/3 RPM.
References:
- The Library of Congress.
- The American Printing House for the Blind declares themselves to be a non-profit organization, however declined to license this device because they would loose the sale of their more expensive record players to their blind customers.
- Audio Book Company, Pasadena, California
- Popular Electronics magazine, Aug. 1957 issue, p. 63-66, article about the Audio Book Co. speed-reducing adapter.
This is not a product for sale. Please contact Steve Hines with questions.
USA
email: [email protected]
phone: 818-507-5812