VIDEO HEADS OPERATION

Thank you electricity, magnetism and gravity. You make the world go round. All of these are very interesting but it is magnetism that makes possible the sending electricity through the air. As shown in the top left in the picture above when electrons flow through a wire a field of magnetism is created around it. It's weak for sure because it just a single wire but if you wind a number of turns of it around an iron bar, as shown in the lower left, an electromagnet can be created. Great for picking up things and making relays, but there's a lot more it can do. Look at the picture in the upper right and here the magnetism is being used to transfer a current from one wire coil to another. This is called a transformer. The iron core is a good conductor of magnetism but air can also be used. See the graphic in the lower right. The only thing required for current to be transferred (inducted) is that the two coils be within a reasonable distance of each other (the closer the better) and that the electrons be moving back and forth in the wires. It must fluctuate, or more properly, collapse and expand. Laying a bar magnet on a coil of wire will not produce electricity, the magnet must be move. Transformers operate because the current is alternating, direct current can't be used in a transformer since it only flows one way. This is just a physical characteristic of electricity. The only way the spinning disk for powering the video heads is successful is because the electricity varies as the signal changes. Click on the picture. On the left is another type of transformer. This one is a called a coupling. Here the same principle of transference of electricity is employed and the medium is air. The picture is exaggerated, in practice they would be in very close proximity to each other without touching. This method is how the signal to the video heads located on a spinning disk moves from one coil to the other. The picture on the right shows a video drum opened up to show the actual coils. There are four coils in this example, or more accurately two pairs, one set for each of the two video heads. As the video disk turns the four coils run very close to each other and as the magnetism changes in them the electricity is transferred. It works both ways, for recording and playback. Here's two added pieces of information on the construction. The gray material surrounding the copper colored wires is made of high density powdered iron. It acts as a magnetic insulator or drain that helps keep stray fields from leaking from one coil to the other. BTW DC current is okay for the electromagnets used in relays, solenoids and other devices that only push or pull. It is also the main player in circuit design. ° To go back click here.mmm mm mmmmm mm mmmmm mm mm mmmm mmmm mmmm ° Maybe your asking yourself now what is the big deal about the video signal needing a larger recording area. What exactly is this frequency and why does it have to be so high or so big? Understanding radio and television signals (electromagnetic waves) is one perplexing questions, so if you would like to know more click here. ° How does the Betamovie, with a video drum half the size of a standard Beta, manage to remain compatible? To find out click here. ° Would you like to examine how electricity and magnetism work together to make recording possible. This link leaves this section and takes you back to the very first panel on the basics of electricity.) To go to THE BASICS, click here. Would you like to skip ahead and go to the next panel "Innovative Betamax" click here. ©Misterßetamax go to homepage