CR X (X being a unique number) is almost always a diode(CR stands for Crystal Rectifier, and dates back to the days of Crystal radio sets). CX is a capacitor, and RX is a resistor (the C and R seem pretty obvious to me). So where the heck did U come from to represent ICs? I believe U stands for Unit, but that is a guess. X stands for Crystal (the kind used in oscillators) I can see that easy enough. Because it strikes me as kind of arbitrary, I have a small list I have created on my schematics on the fly.

transistor = QX???
Schottkey Diode= SDX (actually CR comes closer to being a CR than a silicon diode
LED = DSX (DiSplay)
IC=UX (generic term for an IC)
Resistor = RX
Capacitor = CX
Crystal = XX (Crystal)

Did I miss any? I am also interested in the history of how a designation was created.

Discuss.

 

"Unspecified?"
https://electronics.stackexchange.com/questions/25655/why-is-u-used-for-ics-on-circuit-diagrams

https://electronics.stackexchange.com/questions/10327/standard-nomenclature-for-component-types

 

I saved this awhile ago and usually try and stick to it.


Bit old now but there are more here starting at page 81
https://www.noao.edu/ets/Mechanical/Policies/ANSI Y32.2-1975.pdf

 

In a million years I would not have guessed U was for unspecified, makes as much sense as anything I suppose.

I feel no obligation to use a previous standard I did not learn when I was studying electronics, so I take references like those as suggestions, not rules. As I said many of them are fairly arbitrary anyhow.

 

Eagle uses Qx and Tx for transistors. LTspice seems to like Mx for MOSFETs.

 

Eagle (ver. 7.7) uses IC for integrated circuits regardless of function.

 

Reasonable, but again, I will use what I'm comfortable with.

 

One I had to search for many years ago...RS232 = Recommended Standard #232

 

Hello,

Read this wiki page:
https://en.wikipedia.org/wiki/Reference_designator

Bertus