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DIY Solid State Multiplex Adaptor Plans?
Hello Everyone, I have a late 1950s early 1960s vintage Magnavox Console stereo which has a mono tuner with provisions for a stereo multiplexer adaptor and I know that the multiplexer adaptors for these things are kind of getting harder to find and when you do find them they usually want over $50+ for them on that auction website and anyways I was wondering if there was some sort of FM Stere Multiplexer kit or plans that one could build one from scratch using solid state components that would just hook into the multiplexer RCA jacks on this Magnavox Console's Tuner to make it capable of doing FM Stereo so that I wouldn't have to sink a ton of money into buying a unit off of that auction site. I would like to eventually see if I could flip this console if you know what I mean, and I would like to see if I can get it so that it can have FM Stereo Capabilities so that it would be more desirable and fetch more money.
Thanks for your help, Levi |
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I'm guessing nobody knows of any DIY Solid State Multiplex Adaptor plans or kits...
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#3
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There are some out there. Try the tuner forums on audio asylum or Audiokarma. I was lucky and aquired the remnants after someone else gutted a tube Magnavox for the amp, I got the record changer, tuner, and Multiplex adapter out of it. Its curently in my Motorola SK77 console.
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I searched and found three different IC's and schematics and a full-blown FM receiver. Simple and easy!
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Rick (Sparks) Ethridge |
Audiokarma |
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Get yourself a copy of either an GE tube manual from the 60s (post 1962 - the 1962 manual doesn't have it - they have FM multiplex adapters in the sample circuits in the back.
GE's 1964 manual has one with a 6GH8 as the tube, and uses common Miller 19KHz, 67KHz, and 38KHz coils. I'd scan it, but the manual is still under copyright. You can tap filament and B+ voltage from your existing unit. This was popular in the 1960s - and there are even project plans in Radio Electronics and Popular Electronics magazine, available at American Radio History....
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Brian USN RET (Avionics / Cal) CET- Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! |
#7
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I google Stereo Multiplex Adaptor schematic.
This came up. https://www.google.com/search?q=Soli...ptor+schematic Plenty of schematics in the search. |
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Well the reason why I want a solid state one is because I don't have access to the parts to make a tube powered multiplex adaptor and at least with a solid state one, all I would have to do is get a simple PC Board Kit from Radio Shack and then get all of the components I need for making the multiplex adaptor and then follow the schematic and put it together and then get the right type of Molex Plug like what I need to hook it up to the amplifier for power and then it should be all good to go.
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The problem with finding a solid state adapter is that by 1967, all FM Stereo receivers were solid state, and mono FM was a rarity.
Every adapter I've ever run across is tube based. You could try a FM MPX chip, such as the TDA7040T, a SMT 8 pin device with only about 10 external components, no coils or oddball parts necessary. Powers up with a 3V supply, and output impedance is pretty low, about 5K ohms. The whole adapter could be put in a matchbox. in on pin 8, out on 5/6, pilot (stereo lamp signal) on pin 7, oscillator and low pass filter (both RC networks) on pins 2/3, and power/ground on pins 4 and 1. http://pdf.datasheetcatalog.com/data...ps/TDA7040.pdf
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Brian USN RET (Avionics / Cal) CET- Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! Last edited by Findm-Keepm; 09-29-2017 at 06:38 PM. |
Audiokarma |
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Brian USN RET (Avionics / Cal) CET- Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! |
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I built one to decode TV-MTS for an analog design project in school.
I was able to alter the pilot frequency from 19kHz to 15.7 kHz About as easy as the Philips chip circuit Brian posted above, it used an NTE743 or a Motorola MC1310 IIRC.
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"When resistors increase in value, they're worthless" -Dave G |
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MCM electronics used to sell this kit http://www.communica.co.za/catalog/Details/P0215800312
I bought a bunch of them years ago,probably hiding in my basement somewhere. |
Audiokarma |
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