"GREAT" Meter! The HP 419A DC Null Voltmeter, [RESTORATION]

Comments · 433

• MR

  @MrCarlsonsLab · 6 years ago · pinned

  To learn more about electronics in a very different and effective way, and gain access to Mr Carlson&apos;s personal designs and inventions, visit the Mr Carlson&apos;s Lab Patreon page here: <a href="https://www.patreon.com/MrCarlsonsLab">https://www.patreon.com/MrCarlsonsLab</a>

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• 00

  @001desertrat3 · 6 years ago

  At 73 years of age , &nbsp;I thought that I had seen most everything . . . . and then you show me a &nbsp;Lit Neon Bulb that&apos;s Afraid of the Dark . &nbsp;L O L &nbsp;!

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• MI

  @michaelberry1028 · 6 years ago

  As an old HP engineer I really enjoyed this one, a great restoration.

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• EL

  @ElJohnerino · 6 years ago

  Pro grade comedy timing at the many tested neons segment. Actual lol here.

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• BI

  @billysharp3388 · 1 year ago

  I haven’t kept up with everything you do but just watching what you did here tells me you are far advanced , very intelligent person you are Paul.

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• ST

  @steveyoung8560 · 6 years ago

  &quot;Took the neon out of my night light and tried it.&quot; Now that&apos;s a man on a mission. Great video, Paul.

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• JE

  @jeremyperala839 · 6 years ago

  Jeez, you&apos;re an expert at testing neon bulbs now.

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• JO

  @johnyoungquist6540 · 6 years ago

  The neon chopper was a silent breakthrough used in many instruments like the hp-410C VTVM. Other methods at the time were mechanical and used motorized spinning disks or noisy vibrating reeds yuk! Stable low drift DC gain in those days was hard to get without choppers. Now we would use a single monolithic chopper amp. Neon depends on alpha particles from outer space to provide seed ionization to work in the dark, otherwise ordinary ambient light does it. Lamps that had to work in the dark employed radioactivity. A little KR-85 a radioactive isotope of krypton gas mixed with the neon was often used. Some sort of radioactive electrode or green uranium glass might do it too. The exact neon bulb might have been a carefully guarded secret at the time to prevent copying the design. The little bulb was so common at the time who would think it was special? It would look the same as any other lamp. &nbsp;They would not have unlimited life and for something people left on all the time replacements would be inevitable.<br>The LED solution is the simplest. The 25% duty drive waveform is easiest to do digitally with logic. Careful frequency selection could improve line frequency rejection. &nbsp;Take away all the pre-made solutions we have today and most engineers would be lost.

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• T2

  @T2D.SteveArcs · 6 years ago (edited)

  <a href="https://www.youtube.com/watch?v=vrmwql2msbU&amp;t=1060">17:40</a> long screw damage been a problem for a long time lol

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• KR

  @krz8888888 · 4 years ago

  It&apos;s interesting to see generations of brilliant engineer&apos;s work come through your bench. Lots of those are long gone but we can still appreciate their ingenuity and thought process on this channel

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• DR

  @drstrangelove09 · 5 years ago

  Silly me, I thought the chip is a 81112 but it actually says Pin 8, Pin 11, and Pin 12, and the chip is a TL494... of course! &nbsp;Thank you for a very cool and interesting video and design.

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• HE

  @hestheMaster · 6 years ago (edited)

  This was an incredible restoration of a very sensitive voltmeter. The &nbsp;attention to details on rebuilding and re-engineering of it&apos;s inner workings <br>shows how great of a technically skilled person you are Paul. Thanks for showing &nbsp;how you did it. Much props to you!😍

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