Panatrope Pickup

Panatrope Pickup

Fig. 9 is a photograph of the pickup used on the Panatrope by the British Brunswick Co., to whom I am indebted for permission to describe it.

The component parts are illustrated in Fig. 10.
A strong permanent magnet, A has two soft-iron pole pieces B1, and B2; B1 forms an upper and a lower North pole, and B2 an upper and lower South pole respectively.

The needle-adjusting screw C of the reed D is inserted at the end of the square shaft E (9/16” long by 3/32” square), which is wrapped round with thin rubber and forms the axis about which the reed vibrates.

It is carried in square bearings F formed in the two lower portions of the pole pieces. The audio-frequency coil G surrounds the reed, which plays between adjustable rubber stops. One of these is shown in Fig. 10.

They are carried in brass washers, which fit loosely over the threaded posts, I.

Pressure on the reed is adjusted by turning the milled edges of the two eccentric face-cams J. A brass cover plate K is fitted over the front of the pick-up.
The action is easily followed. When the needle moves to the left the direction of the flux is from the lower (lefthand) North pole upwards through the reed to the top (righthand) South pole. When the needle moves to the right the direction of the flux is downwards through the reed from the upper North pole to the lower South pole.

An alternating E.M.F. is therefore generated in the audio-frequency coil. The reed is 5/8” in length. The portion within the coil is 1/8” square, while the top is ¼” wide and only 21/1000 thick.

The fact that the bearings and axis of vibration of the reed are square is curious and is perhaps intended to ensure that the rubber is compressed at right angles to its surface.

The arrangement of the needle-adjusting screw on this axis is an excellent feature of the design.
A note concerning the first demonstration of this instrument appeared in The Wireless World on October 13th, 1926. Those who have heard the Panatrope will not need to be told that the quality is remarkable.

Wireless World January 27, 1927, Pages 97, 98.

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