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Lots of older TVs use electrostatic deflection (4 plates inside the picture tube to control the beam), all these old motorolas I keep picking up are like this, here's a schematic. The 7JP4 is the electrostatic picture tube used in the Motorola, any TV that says it has one of these is electrostatic. The electrostatic crt below is the 7GP4.
The voltage is varied across the plates inside the tube and this is what deflects the beam, (there are no permanent magnets involved) Now some early electromagnetic sets use a magnet around the neck of the tube behind the yoke for focusing, my Hoffman 610 uses one of these, and some sets also used an electromagnet instead, the Admiral 20A1 uses one. Here is a picture of the Hoffman showing the magnet. The Hoffman uses the 10BP4 one of the most common tubes in early electromagnetic sets.
Last edited by Adam; 09-13-2009 at 10:37 AM.
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