How to Read Your Schematic Plates

Schematic PlatesSchematics and diagrams have been used by many companies and businesses for a number of reasons, which include safety, proper operations, and troubleshooting. Being able to read these plates is not an easy task, but it can be learned. Since these plates carry symbols that represent certain parts of a system, instead of the actual image of such parts, if you are not aware of what these representations mean, you may find it hard to read such metal plates and diagrams.

In order to understand what schematic plates are trying to tell you, you will need to first learn what these symbols mean. There are many commonly used symbols utilized for such plates, with the most common ones being symbols that are used for circuitry and electronics. If the plates you are to use are not for electronics and electrical requirements, you may need to search for the symbols that are used for the plates you need to read.

The most commonly used symbols when it comes to schematics used for electronics include symbols that indicate the location of resistors, capacitors, inductors, power sources, and transistors, to mention a few. Here are some of the more commonly used ones and what each symbol means:


Resistors – these are represented by either zigzag lines or a rectangle in between two short lines that have dots (which represent terminals) on each end.

Variable Resistors – these are similar in shape to the standard resistor, but are drawn with a diagonal arrow running across the zigzag lines. If a potentiometer is in the place of the variable resistor, the zigzag lines will have an arrow pointing towards it, with dots (which represent terminals) on the open ends of the lines in these symbols.

Capacitors – these can be seen in two variants – polarized and non-polarized. The former is represented by a symbol that has two short lines with dots at the end (which represent terminals) and with one short line ending in a curved line (making this part of the symbol look like an anchor) and the other short line ending in a straight line (forming a T). The latter is represented by two Ts that have the tops facing each other, and the opposite lines on each ending in dots (which represent terminals).

Inductors – you will see these represented on diagrams or schematic plates as loops or spiraled coils with short straight lines at the end that have dots on each tip. The international variant of this is a filled-in rectangle with short straight lines on either end that also end in dots.

Switches – these can come in many forms, with the most common being the single pole-single throw switch (SPST) and the single pole-dual throw switch (SPDT). Other switches that you can find in diagrams SP3T and DPDT.

Other symbols you will find being represented in diagrams that are used to show circuitry include diodes (lines with triangles), voltage sources (circles with negative and positive symbols), batteries, and logic gates.  

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