Photograph of photograph of radio chassis display with instructions, Southern California, 1925. "Specification for Coil Shown, Tubing - any kind of insulated Tubing, Diameter - 2 5/8" - Length 3/8", 1st Coil - Regeneration 10 Turns, Primary - Special Retardation 1 Turn, Secondary - 6 Turns, Primary - 6 Turns, Secondary - 6 Turns, Primary - 6 Turns, Secondary - 6 Turns, Primary - Special Retardation 1 Turn, Secondary 24 Turns, 2nd Coil, Regeneration - 10 Turns, Secondary - 48 Turns; Note - Construction of coils as shown in the illustration is preffered for the Willy's Circut but patent covers any form of winding where the primary is used between secondary; 400 Ohms Resistance Regeneration Control, This circuit will work without Regeneration; Secondary; Primary - Special Retardation winding in Ends. This winding Guaranteed to cut off Re-radiation in 8' without affecting the distance and to increase selectivity and to cut off 50% of all noise, See Claims 2-3-4; Primary between Secondary; Reversing Feedback; Ordinary Feedback; Distance between coils 2 1/2" to 6" depending on Selectivity wanted (without effecting long distance)" -- instructions on display. "Trim print To Here before rephotoing" -- writing on frame. "Chelten" -- on machine part.