• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Safety Practices, General and Ultra-High Voltage

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#561
Around here folks often use “V” for DC and “v” for AC. Same for “I” and “i.” However never noticed it for “A.” (Rarely used to avoid confusion.)

Things get confusing for “M” and “m.” Depends on where and how it is used, can be a multiplier of 1,000, .001 or 1,000,000! In trade for counting pieces it is often 1,000!
 
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#562
In the electrical world it usually is Mega and milli. So MA en mA, MV and mV all better not mixed up. It would be technically illiterate when writing 100 MV at 1 MA when 0.1V at 0.001A is meant. KV would be kelvinvolt or something like that. AFAIK only ones upper case are Mega, Giga, Tera, Peta, Exa and higher.

V for DC/v for AC to indicate the value of U is a local habit I think? Here AC and DC are added so in english to avoid any possible confusion.

Just had a german tech over that triggered a (his words) RCD.
 
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#563
Capital V is a large signal value, either DC or AC. Power supply voltage, AC power line voltage, AC or DC signal voltage that is large enough in magnitude to upset quiescent conditions or generate detectable harmonics. Small v or i is supposed to indicate a small signal value which is superimposed. It can be AC or DC. Usually AC, but a small signal can be mathematically defined at zero frequency, and analyzed as a linear pertubation.

Small signal values would never refer to anything in the kilovolts, at least not in any power distribution system being used on earth right now. Maybe if you were looking at the RF spectrum of a lightning strike or something. A 10 volt output of a class A amplifier can almost be looked at as a “small” signal, but technically if it’s large enough to generate harmonics that come out of the noise floor the sigal isn’t “small” anymore. At least not mathematically.
 
#564
Working with anything above 500V, especially where signals have high freq and or slew rates, requires utmost precautions. A proper high voltage probe (x100), rubber gloves, etc. In my work with RF transmitters I found that you don't actual have to touch a high voltage node to get a serious shock; sometimes being within a few inches of it is enough for it to seek and find you through capacitive coupling (yes, even through rubber gloves) or simply arcing.
 
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#569
To avoid mistakes U from the Latin ugere was agreed upon. I would not know who thought it was clever to use V (already agreed to be used for velocity in lower case) expressed in either v or V and make triple mistakes.

If you can’t do the talk you can’t do the walk 🙂
 
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#570
I often get fed up with acronyms, and even with single letters that describe something.
To capitalize, or not to capitalize for example.
Try and make things obvious when possible. Study historical use of terms.

Mr. Hertz turned over in his grave, when he found out there were no longer any Cycles.

A classical radio station should use some logic in naming the keys of a musical piece.
A Flat Minor is not what I want to see. I want to see a-flat minor, does that make sense?
A-Major makes sense to me.
minor keys should always use lower case.
Major keys should always use Upper case.
Just a desire to instantly know what the key is, when I see the readout on my car radio when I am proceeding at 50MPH.

Names:
Look up a historical definition of a Tetrode. No, you do not have to go all the way back to Greek; just check early history.
A Tetrode consists of filament/cathode; control grid; screen grid; and plate. Effectively 4 elements, not 3, not 5.

A Beam Power Tetrode has 5 elements.
Filament/cathode; control grid; screen grid; beam former(s); and plate
You might call it a Tetrode-Plus; if you insist on using the term Tetrode.

History is the poorest teacher, nobody pays attention.
 
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#571
jean-paul said:
It is U for voltage.

v is for velocity.

Sorry.
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Actually on this side of the pond we use “E” not “U.” It represents Eletro-Motive Force or EMF.

If I write 120v for a power line technically it is AC, or alternating current not air conditioning! However is almost always written as 120 VAC or Vac. (Not to be confused with vacuum.)

If I write 12V most around here would presume DC. But precision would be 12Vdc or 12VDC.
 
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#576
simon7000 said:
If I write 120v for a power line technically it is AC, or alternating current not air conditioning! However is almost always written as 120 VAC or Vac. (Not to be confused with vacuum.)

If I write 12V most around here would presume DC. But precision would be 12Vdc or 12VDC.
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To be compliant with the rules of the BIPM/SI, you would have to write 120 V or 12 V and mention somewhere else that it is AC or DC, for example as an index of the symbol of the physical quantity or in words or acronyms that are not attached to the unit symbol. It seems logical, as the unit doesn't change depending on whether it is AC or DC.
 
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#580
MarcelvdG said:
To be compliant with the rules of the BIPM/SI, you would have to write 120 V or 12 V and mention somewhere else that it is AC or DC, for example as an index of the symbol of the physical quantity or in words or acronyms that are not attached to the unit symbol. It seems logical, as the unit doesn't change depending on whether it is AC or DC.
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Interesting, can you site some common text where they refer to the voltage being AC or DC apart from the “V”? I have seen “V ac” on rare occasions.
 
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