73 lines
3.5 KiB
Plaintext
73 lines
3.5 KiB
Plaintext
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THE MAGENTA BOX
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---------------
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This is a portable ringing generator which, if connected to a phone
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line, will make the phone on the end of it ring. It works by using a
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relay as a vibrator to generate A.C. which is then stepped up by a
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transformer and fed through a capacitor into the phone line to make the
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phone ring!
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YOU WILL NEED:
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One 5V relay with single pole change-over (SPCO) contacts
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One 6-0-6V mains transformer {KEZ SEZ: US users see text for mod.}
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Two 2uF 250V non-electrolytic capacitors
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One 6V lantern battery
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One push-to-make switch
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Wire
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HOW TO MAKE IT:
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The circuit diagram shows the relay in the normal state, ie when
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current is NOT Flowing!
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---- SWITCH
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+---o o-------+----------------+ +----------------+
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------- } 6 |. .| |
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--- RELAY } } {
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------- COIL } 0 } { OUTPUT
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--- } +----} { TO PHONE
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------- |' | } { WIRES
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--- COM o NC | } { 2*2uF 250V
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------- +-----o/ | |' `| |
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--- | o NO | 6 NOT | +---||---+ |
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| | | | USED | | | |
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+------+ +------------+ +---+---||---+---+
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HOW TO USE IT:
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Connect the output wires to a suitable beige boxing point on a phone
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line. {or use a modular plug - middle two pins of the US type, outer
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two pins of the four-way UK type}
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HOW IT WORKS:
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The telephone ringing voltage is about 90V rms, which is about 255V
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peak to peak. This circuit feeds 6V peak to peak into the 6V winding of
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a transformer, which should generate 240V peak to peak in the 240V
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primary. {So in America you will have to use a 3-0-3V transformer to
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get the right step-up ratio, as your mains voltage is only 120V.} The
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relay is wired through its own contacts. At first a current flows, so
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the contacts change over and the battery current now flows into the
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transformer instead of the relay coil. This produces a pulse of current
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in the other winding, which flows through the capacitors and into the
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phone line. Meanwhile, the relay isn't connected any more and so flies
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back. This produces a pulse of current in the opposite direction on the
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mains side of the transformer. Any phone on the line will ring while
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the switch is held closed. With practice you should be able to emulate
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the ringing sound perfectly! It will certainly confuse a few people!
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Brought to you by ...... . .... . . ... .....
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: :..: :.. :.' .:.......:.
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: : : :... : `. `... .:...
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disclaimer: this is for informational purposes only. no responsibility
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is accepted for any consequences of use or misuse of any information
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contained herein. any material whose source i have not acknowledged is
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believed to be my own - if it sounds like something you invented, just
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remember great minds think alike.
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