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Suggestions for a beginner's book on valves

Discussion in 'classic' started by chiily, Aug 23, 2022.

  1. Marchbanks

    Marchbanks Hat and Beard member

    Just the two of each? At least the others were unscathed.


    I don't really remember much about my first shock from the mains, at a similar age. The front came off a plug I was trying to pull out of a socket. Oh dear. Never mind, if I just put my fingers very carefully around the outside... then I was on the opposite side of the room for some reason.
  2. chiily

    chiily PFM Special Builder

    For me I rolled over, as I was kneeling down, and as I rolled away, managed to pull one the wires out of one hand, for a time it felt I was doing the front crawl at 50 mph :) I did have blisters all across my shoulders and up my arms. My grandmother, the only adult in the house at the time gave me sweet milky tea; ah the tonic for all moments.

    I've never had the delight of a shock throwing me across the room, did if feel like flying? :D:p
  3. a.palfreyman

    a.palfreyman pfm Member

    Bl00dy hell man, that's pretty serious.
    Biggest shock I ever had was messing about with the solenoid on a washing machine. D4mned thing would occasionally stick and the only way I could play with it was live. Reaching down inside the machine between drum and door, suddenly got a rapid pulsing in the same arm muscle where it was close to the chassis... Thank goodness I had rubber soled boots on.
  4. fran

    fran pfm Member

    Please don't confuse a nasty shock from AC (which of course could kill you) with a DC high voltage shock. Picture yourself, one hand resting on the edge of the chassis, and the other probing about. You accidentally touch something with a DC charge (which could be a charged capacitor even if you have the power off). The shock travels up your arm, across your chest, stopping your heart in the process as it exits through your other hand which was conveniently sitting on the chassis (ground). You die from a stopped heart, not the shock.

    All the channels on youtube will mention this somewhere or other.
  5. martin clark

    martin clark pinko bodger

    Oh, and you can't let go the whole time because of the muscle contraction : o

    Had a bit of fright learning this for myself on a c 350vdc supply built for a an old valve tuner - brushed the output by mistake and ..that's weird. Saved by having no hard path to either or any other part at different potential, being sat on the carpet at the time, and a rather high-value series resistor my fleeting contact was downstream of.

    Very sobering stuff.
    Last edited: Aug 27, 2022
  6. Yank

    Yank Bulbous Also Tapered

    Americans of my parents' generation just couldn't accept a TV in their front room unless it was in one of those massive cabinets. Even if all the gaudy scrollwork on the front was actually injection-molded plastic. Tolerating a plain TV in a metal cabinet was just culturally impossible for them.
  7. fran

    fran pfm Member

    My learning moment came when I was given a homemade valve amp by a guy who was selling his late fathers stuff - it was thrown in with whatever else I was buying. It turned out to be an attempt at a mullard 5-20, had lovely sowter transformers (which I still have). Anyway, I turned it upside down, connected up power, was probing and wasn't getting any voltage after the rectifier. BY CHANCE I put the probe against the mains earth (of course the chassis wasn't earthed) and saw it flick to 450V. The damn chassis was live and it pure luck I hadn't touched it.

    Taught me a lesson, nearly puked after I realised what was happening. One of those moments like a near miss in a car crash - you sit back and can't quite believe you got away with that, and how close you came to oblivion.
  8. a.palfreyman

    a.palfreyman pfm Member

    Thick soled boots and stand on carpet. Keep your spare hand behind your back so you don't lean on a potential earth path...
  9. chiily

    chiily PFM Special Builder

  10. AmadeusMozart

    AmadeusMozart pfm Member

  11. chiily

    chiily PFM Special Builder

    What sort of major errors? I'm intrigued. His books are well received from what I've read.
  12. AmadeusMozart

    AmadeusMozart pfm Member

    Using voltages above ratings greatly reducing tubelife. And those create other risks as well if not recognised. (E.g. flashover and/or destructive to other tubes. Some lead to gradual diminished performance with the builder going round in circles trying to figure out what is happening resulting in blaming "bad tubes".)

    Just because most do not know better and find it a reasaonable read does it not make correct. RDH is not an easy read and I can understand the appeal of his books.
  13. Darmok

    Darmok "In Lation, Trans Lost."

  14. Pete MB&D

    Pete MB&D Pete Maddex, the one and only!

    I used to fix tvs and often when you clipped the 0v meter lead the speaker would crackle then you knew the mains plug was wired backwards and live was connected to the chassis.

  15. Barrymagrec

    Barrymagrec pfm Member

    Very true.

    Worst shock I have ever had was from the rectified and smoothed mains solenoid supply on a tape machine -finger brushed the relay and I couldn`t let go of the chassis bar I was delving behind, I still don`t know how I managed to pull my hand away, still have the burn scar 49 years later. I apparently stood up, looked surprised for a moment and then collapsed onto the floor.
  16. peter wood

    peter wood pfm Member

    I’d get the Morgan Jones book as a reference - But first go back to elementary electronics for a recap.
  17. Darmok

    Darmok "In Lation, Trans Lost."

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