Old TV sets and ideas of what to use the parts for

Discussion in 'General Electronics Chat' started by Rolland B. Heiss, Mar 8, 2015.

  1. Rolland B. Heiss

    Thread Starter Member

    Feb 4, 2015
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    Today after work I picked up 4 old TV sets and tomorrow I am going to pick up 4 more from another guy. I've got a whole host of parts to utilize already and therefore I'd like to ask all of you who are more learned than I what you would build first with the parts from an old TV set. CRT.. not flat screen. Of course the amount of copper in them is quite good and I plan to properly recycle the parts I do not use but give me a project idea and I'll think about making something on my next two days off which are Tues. and Wed. It's not that I don't have an imagination but sometimes it is best to ask the experts what they would consider doing with the parts if you get my drift!
     
  2. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    Should exposed core-space receptive of a few (added) turns be seen to exist, the LOPTs are quite useful in LVDC to HVDC converters (using Royer or resonant-Royer topologies) thus one may produce up to 40KV @ 10+ mA (several hundred watts) intermittently or as much as 2 ma continuously --- Useful for low energy radiography, ion motion experimentation, etc...

    Additionally, you may wish to salvage BJTs, power MOSFETS, fast recovery diodes, ferrite transformers/inductors, saturable reactors and nice (i.e. low ESR) caps from the SMPS circuits...

    Other items of interest include discrete RF devices (BJTs, FETs, varactors), and, by all means, the video amplifier (Y-amplifier) BJTs

    Have fun! :D
    HP

    PS
    While I'd like to avise you on LOPT projects, I'm not certain I can do so within the confines of the fourm's TOS. Granted, although 'HV' is no more or less dangerous than many 'acceptable' topics, it tends, sadly, to be prey of abuse...
     
    Last edited: Mar 9, 2015
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  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    The lopt is a transformer located with an HT lead to the back of the tube, it has a large sucker cap on it, this feeds the screen with 30-40 Kv ,so when you remove the cap the screen will still be charged up and will need discharging using a couple of screwdrivers shorting the socket to chassis,

    the scan coils are on the neck of the tube are rich in copper wire.
     
  4. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    I would consider (and recommend) leaving the parts, and the TVs in which they are contained, exactly where they are.

    It's much better to start with a clear plan for what you wish to build and then to acquire the correct parts, than to start with junk and hope for inspiration. Otherwise, I guarantee that in 6 months time you'll have nothing but a pile of junk, which used to be 8x TVs, taking up valuable space. You will then need to waste time and money, which would have been better spent doing something useful, disposing of the bits .
     
    Last edited: Mar 9, 2015
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  5. Rolland B. Heiss

    Thread Starter Member

    Feb 4, 2015
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    I appreciate the advice and the perspective you have offered up in response to the question asked. As it turns out I have already collected many useful components for projects I've been wanting to delve into. Projects I can currently understand that is! Other components will be waiting for another time and it will be nice to have them readily available when the other times come. As for disposal of the unwanted stuff, I happen to live in Washington state and in 2006 they passed a law stating that organizations or businesses considered what are termed as 'collectors' are required by law to take encased TV sets and certain other items for free. Therefore, places such as Goodwill Industries, Best Buy and others will recycle what I don't need as long as they are encased within the original outer plastic or metal enclosure (depending upon what you are recycling). Also, the units I am harvesting are well beyond repair. I know the general unspoken rule is that if a device works or can be fixed it is better to use it or sell it for its original purpose.
     
  6. DickCappels

    Moderator

    Aug 21, 2008
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    One thing that you should keep in mind is that CRTs can hold a soak charge in the capacitor formed glass between the inner metalization and the outer conductive coating (the black stuff). At room temperatures, the glass is an excellent insulator and on even a small color tube a charge large enough to give you a nasty surprise can remain for YEARS after the television set or monitor was turned off. Many CRT circuit have bleeders in the form of the focus and G2 adjustments but after the tube has been removed from the circuit, the charge from deep in the glass will build up between the anode cap button and the outer conductive coating.

    Keep one hand in your back pocket and be sure to be positioned so that a reaction to a shock won't cause you to hurt yourself (such as by scraping your arm on chassis or components as you involuntarily pull it back).

    With the set disconnected from the AC Line or other source of power, use a piece of wire to connect the metal shaft of a screwdriver to the metal contact to the outside of the CRT (this can be a piece or braid held against the back CRT by springs or in more recent models, phosphor bronze finger contacts extending from one circuit board (usually the CRT socket board) or other contact. Keeping one hand in your back pocket while holding the screwdriver's plastic handle (and fingers clear of the metal shaft) carefully slide the screwdriver tip under the CRT anode cap and discharge any charge that may be present. After that, it is safe to remove the anode cap. This is done by pinching the back of the anode cap to squeeze the metal clips together so they can release their grip on the inside of the anode button.

    After removing the anode cap, short the anode button to the outer conductive coating then then place a piece of electrical tape over the anode button to prevent accidental contact. Under the tape you might want to have a piece of wire from the outer conductive coating to the anode button. Connect the wire to the outer conductive coating before connecting it to the anode button.
     
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  7. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    I concur with DickCappels! --- I can attest from my own (sorry) experience that dielectric absorption is a very real phenomenon!

    On another safety note, if you do not wish to salvage the CRT itself, it may be advisable to re-pressurize it... Do this by carefully breaking the exhaust tip (with pliers) or damaging the glass-to-metal seals at the pins via carefully applied torsion to the socket (or, if so equipped, to the socket & video Amp. assembly). And, oh yeah -- unless you're languishing under an unfulfilled lifetime's ambition to reinvent yourself as a pencil monger -- wear a safety visor!!! Do forgive the paternalistic tone -- I'd speak to my own parents that way where safety was at issue -- and they're LOTS smarter than I! :)

    Best regards
    HP
     
    Last edited: Mar 10, 2015
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  8. wayneh

    Expert

    Sep 9, 2010
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    I used to scavenge parts from everything I could find, and I still do some part pulling, but over time I've evolved closer to the strategy from blocco. If I'm investing time to design and build something, I do NOT want to risk using a bad or about-to-go-bad part. Nor do I want to wear out my soldering iron and risk burning my fingers to pull a 4¢ part off an old PCB. I've also learned how incredibly cheap some parts are (resistors, diodes, small capacitors, small transistors) when you get them from a real supplier instead of from the Radio Shack. Since I usually have to order something to complete a project anyway, getting some fresh parts thrown in with my order adds next to nothing to the cost. Need one resistor? Order 20. One diode? Get 10.

    Now I'm more selective in my scavenging. Copper wire from the CRT? Yes, I'd probably grab that if I had a plan to tinker in winding a coil. Big, high-voltage MOSFETs from he power supply? Yeah, I'll grab those because they can be $5 or more to order. Anything electromechanical grabs my eye - relays, fans, switches, motors, that sort of thing. Old VCRs are loaded with motors! These items are great for tinkering projects and can be expensive.
     
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  9. Lundwall_Paul

    Member

    Oct 18, 2011
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    Too bad that you don't live in NH. Our town has a an oversized storage bin where people drop off there trash electronics. TVs, printers, computers... They just do not want the circuits in the regular trash.
     
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  10. ian field

    Distinguished Member

    Oct 27, 2012
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    How old? - anything valve era is probably best offered to a museum.

    Thhrough-hole components are getting rare as rocking horse manure - the dwindling supply of scrap TVs is getting a bit sought after!
     
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  11. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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  12. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    Make a really BIG oscilloscope! :)
     
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  13. Rolland B. Heiss

    Thread Starter Member

    Feb 4, 2015
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    I wouldn't scrap or scavenge anything that might have value, sentimentally or historically (and often the two go hand in hand don't they?). I've got some very old electrical units of all kinds apart from TV sets that I sometimes glance at with a notion to salvage certain things in them I could use, but I can't and won't bring myself to do it! The TV sets I'm working with here are mostly the big black plastic encased monsters and nearly all of them have been sitting out in the weather for a year or more. The oldest set I got on my two day run after work each day has a fake wood panel frame but I haven't yet read the date of manufacture on the back. It's got to be 1970 something. That one wasn't sitting out in the weather and I will probably attempt to fix it, although it is missing one of the front channel knobs. It has the old UHF knob as well and that is the one that is still intact.
     
  14. Rolland B. Heiss

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    Feb 4, 2015
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    I've thought about doing that at some point! :)
     
  15. ian field

    Distinguished Member

    Oct 27, 2012
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    Many years ago, Elektor published a TV scope project - but I vaguely remember the TV had to be up-ended for the trace to be level.

    If anyone can be bothered finding out which issue, I can check whether its in my archive.
     
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  16. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    Owing to the nonlinear and, in fact, near discontinuous frequency response inherent to magnetic deflection schemes, such do not lend themselves to anything approaching 'faithful' oscillography . --- That said, such a device could make an appealing 'light show' display if fed, for instance, with an audio signal :)

    Best regards
    HP

    PS --- before anyone reminds me that certian DPOs, Logic analyzers, etc... employ magnetically deflected CRTs I direct your attention to the fact that, in such equipment, the CRT is merely a display device as opposed to a metric component of the apparatus! :p
     
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  17. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    Yeah, you haven't lived till you've been knocked on your kiester by a second anode lead. :)
     
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  18. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    The black stuff is called aquadag:
    http://en.wikipedia.org/wiki/Aquadag

    It's deflucculated. And if you don't discharge it properly, you could end up deflocculated too!
     
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  19. Rolland B. Heiss

    Thread Starter Member

    Feb 4, 2015
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    It may not be precise but the modification can give a person the general visual wave form. Useful for someone who has an old TV sitting around (and a little bit of time) but no oscilloscope. I fall into that category at the moment! ;)
     
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  20. Rolland B. Heiss

    Thread Starter Member

    Feb 4, 2015
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    True! Graphite is an interesting thing. Today after waking up (this is my last day off from work this week) I was bored and trying to get the sleep out of my eyes. So I picked up a pencil and doodled a few thick lines on an envelope and placed a 9v battery upside down on the doodle lines. Then I pulled an LED from my part drawer and touched it to the graphite doodle lines while still trying to get the sleep out of my eyes. Old trick but when the LED lit up a bit of sleep left my eyes and I began to feel the wonder of the world I felt when I was much younger than I am today. Encase that stuff in a vacuum and you could run into trouble for sure!
     
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