[...]
I do discriminate Zener diodes because it's useful in troubleshooting. If a diode on the PCB says "DZ" instead of "D", you know that just probing VF with a multimeter isn't enough to make sure it's working.
That would be one valid reason to use a different symbol.
I do RV and CV because it gives a quick indication of trim points and the like, either looking through a parts listing or just doing a Ctrl-F on the schematic. RT for Thermistor is more or less out of habit - now I'm considering editing that to R in my library. They're not fundamentally different and it's not really useful to have the indication.
You do have a point in the logic, but i doubt i am going to change the way i do it.
My reasons:
- There are standards that define the designators you should use. Observing the standards is voluntary but they are the result of some effort and should not be dismissed out of hand. Observing half a standard is the same as observing none of it, as far as i see things.
- Looking at someone else's schematic, you cannot always know what internal logic they have used to adjust the standard designators. So in the end it tends to add more noise than signal to everyoone else but the designer him/herself. A thing like 'DZ' instead of 'D' is easy but there are so many completely opaque cases where you just cannot know.
- The component designators are intended to classify the components themselves for clarity. Now different people have different values for 'clarity' and i only speak for myself. My logic is that you don't attach meanings to the component symbol other than those helping to classify the component itself. Not how it is used, not any ancillary info related to the physical placement or whatever secondary info. That introduces uncontrolled extra dimensions into the classification and causes the classification to lose its coherence.
- All classification info is contained in the class designator and component symbol. You don't repeat the info across those two. This is the reason why my diodes are all D and the graphical symbol distinguishes the further nature of the diode. I do understand the point of 'DZ' but would not use it myself.
I would prefer documents other than the parts list to specify things like adjustments and test points and similar. I guess if you have the trimmable components designated differently then you can pick them out easily from the parts list. That however doesn't tell you anything about how to actually perform the adjustment itself, only what components may be adjustable. If you don't want to leave the adjustment rules as an exercise for the reader then you must document the procedure. And if you do then do you really need the separate designators any more? This has been my logic, so far.
I don't have a big argument against your way of doing things, i just go by a somewhat different logic. Maybe it comes from how i have experienced and assimilated the logic of the big projects in my earlier jobs. I am thinking of say the electrical and electronics "schematic" of a paper machine. The complete set of schematics is several meters of large folders on a shelf. Practically every different kind of electronic or electromechanical component manufactured by man appears somewhere in the diagrams, or so it seems. I guess the principles i listed above were taken to their logical endpoint there, especially the part concerning documentation of testing and adjustment. Certainly, a lot of that was "standard" in the sense that it didn't vary between projects but documented it was, nevertheless.
I have found that the principle scales nicely downwards - you just need to keep things in their logical compartments and see that every compartment is done as required. Not a big deal and not that much extra work really. I have yet to encounter a software project that failed because the programmer coudn't type fast enough after spending time documenting the architecture of the solution, or an electronics project that failed because there was no time to write a necessary design document. On the other hand, i have seen projects fail because those things were not done.
OK i digressed quite far from the question of component designators. I just tried to make the point why i do things my way, and that there is a reason for it. Other people have different priorities and life manages to go on..
Home
Help
Search
Login
Register
