Transistor Identification using "Q"?

[Kevco]

This is a curious question that came to mind while looking at my daughter's broken stereo, from probably the 1960 or 70s.

I found an online schematic for it, and they used "TR##" to identify transistors on the schematic. Yet, it seems like most schematics I've used over the years, identify the transistors using "Q##". In both cases, the ## being a number for each transistor in the circuit. "TR##" seems to be more appropriate, instead of "Q##", which is common.

The question: where did the practice of using "Q##" to identify transistors come from, rather than using "TR##"? Compare that to resistors being "R##", or capacitors being "C##", etc.

Again, this is nothing serious, but rather more of a curiosity. I can't really think of a reason myself.

Kevco

[kt315]

in my opinion TR may be misleaded with TRansformer.

[Qiaozhi]

Also interesting is "U" for integrated circuits, when initially "IC" was used.
As usual, international standards bodies have to put their finger in the pie, and I suspect this is the main reason for some quirkiness in certain reference designators. As KT said, using "TR" could potentially add some confusion between transistor and transformer. The standard practice for transformers nowadays is to use "T".

So I suppose, the real question is why use "Q" instead of a different character. Actually, if you look at the standards list, you will notice that "Q" is about the only character that was not being used. Anyway, "Q" is a rather good character to use .., in my opinion.

[Rumcajs]

Hi,

here it is an another rose:
http://www.puskas.hu/r_tanfolyam/tapegysegek.pdf

similar to many old European docu., identify
transistors with T# symbols,
transformators with TR#,
Zener-diodes with Z,
ic-s: U#, etc.

Im dont known, the transistor symbol currently why Q#, (and newest TZ# nono!) but im thinking the CAD-program writers adding this exotic notations.

Brg

Rumcajs

[taliesin]

they had to call it something !!

[kt315]

american grapho standart seems slightly strange for me. for example you do not see power value of resistors, in soviet standart you clearly see the power on symbol.

[taliesin]

yes well understood.i was just thinking what would someone call a transistor , for common understanding ?. as long as the connection is made whats the problem .like universal comprehension of what is described ? translation is a dubious art

[Kevco]

Oh well..

It was just a curiosity why 'Q' was used for transistor identification - if there was a genuine reason. I could think of Q being a symbol for electrostatic charges, but was hoping another similar connection would be the reason for Q & transistors.

Looks like it's just a traditional use, rather than a genuine reason.

No big deal, just wanted to see if another could come up with a valid reason. Thanks!

Kevco

[Altra]

I always thought the term "Q" was related to digital switching which transistors do well? If you look at a data sheet for a flip flop the outputs are labeled Q and Q not.

ICs, U = Unit?

The one thing thats really screwed up is capacitor markings!

"470" - 47pf or 470pf have been bitten by this a time or two.

And why do they have to use dark blue with faded colors on 1% resistors? But the 5% ones are easy to read bright colors.

[simonbaker]

... Anyway, "Q" is a rather good character to use .., in my opinion.

And we always enjoy your amplifications on any subject...!

[Qiaozhi]

And we always enjoy your amplifications on any subject...!

I may not be omnipotent (like that other "Q") but I often have an opinion.

[fabius]

Hi, I also do not the exact reason for using Q to designate transistors, however I know why U is used for integrated circuits.

When first IC's appeared, they were usually named micro-circuits, for example the first commercial op-amp was named micro-amplifier 741, shorted as uA741, spelled mu-a.
The same use for the first digital ICs, so U stands for "micro".

The same is to call capacitors, 470 microfarads becomes 470 uF.

[Jerry]

I think it is just an agreed upon term adopted so everyone is on the same page. Sometimes they make sense and others not so much. Years ago frequency used to be measured in cycles per second or Kcs, Mcs which I thought was pretty descriptive. Now we have Hz, Khz, Mhz named in honor of an individual (Heinrich Hertz) instead of a descriptive function. As long as every one know what it means it does not matter.

Jerry

[Qiaozhi]

I think it is just an agreed upon term adopted so everyone is on the same page. Sometimes they make sense and others not so much. Years ago frequency used to be measured in cycles per second or Kcs, Mcs which I thought was pretty descriptive. Now we have Hz, Khz, Mhz named in honor of an individual (Heinrich Hertz) instead of a descriptive function. As long as every one know what it means it does not matter.

Jerry

To be pedantic ... it's actually Hz, kHz and MHz. When the letter refers to a person, then it is a capital letter. That's why the k is lower-case, as it means kilo. Capital K stands for Kelvin. So why (I hear you ask) is the M in upper-case? Simple - because it stands for mega, and lower-case m stands for milli.

[Vortxrex]

I may not be omnipotent (like that other "Q") but I often have an opinion.

I think an "all Knowing" op-amp, made w/ omnipotent transistors is just what we need