| General > General Technical Chat |
| Electrolytic capacitor symbols on circuit diagrams – point to watch out for ! |
| << < (2/2) |
| David Hess:
In practice I take the curved line to mean electrolytic capacitor which includes the various tantalum parts, although not all electrolytic capacitors are polar. |
| Gyro:
I still like the old British symbol. Less susceptible to misinterpretation on sloppy back of a fag packet schematics and poor scans, even if it is a bit harder to draw. EDIT: --- Quote from: Chris56000 on August 07, 2021, 02:02:33 pm ---Amber, who manufacture a range of audio testing equipment, use the conventional symbol of a black plate and an open plate, but for reasons known only to themselves, they've used the black plate as positive ! --- End quote --- ... even if you do get idiots who draw it upside down. |
| Siwastaja:
If there is no plus symbol, I assume whoever draw that symbol is either just clueless, or a total sadistic dickhead if they omitted that on purpose. In either case, I reverse-engineer the circuit enough to deduce the correct polarity, this usually is trivial. It's good to check that anyway. |
| floobydust:
Most important is to be able to see the polarity on a PCB- with the cap installed. I use a silkscreen arc and (+) outside the part body (although Altium is stupid still and thinks the part is a square giving false clearance violations). I've always used the electrolytic capacitor symbol with a curved plate, it was used in American and Asian schematics back to the 1980's and that's what I learned and stay with. Europe has their own versions. I use straight plates for ceramic caps and very rarely curved plate (with no polarity) for film caps where the outside foil end is critical. |
| Chris56000:
Hi! There is also the "non–polarised" electrolytic capacitor, manufactured with a double layer oxide film internally so that it is effectively two polarised capacitors of twice the value, internally connected "back–to–back", commonly found in speaker crossover networks, op–amp audio circuits where a large value is needed in a small size where the polarization voltage is low and subject to reversal, and very occasionally in some old CRT monitors for the "pincushion distortion" correction circuit. The conventional symbol for this is two open plates – physically they look exactly like a standard polarised capacitor but without a polarity marking (you did find "BP" on some older types), altho' large axial lead ones occasionally turn up. Chris Williams |
| Navigation |
| Message Index |
| Previous page |