When designing and assembling various electronic equipment (CEA), certain rules should be adhered to. This will allow achieving the maximum possible positive results, such as the absence of cross-connections, pickups, self-excitation from parasitic capacitance or inductance. And this, in turn, will provide better coordination of electronic cascades, facilitate tuning and make it possible to obtain all the declared parameters of the assembled circuit.
Illustrative photo
10 rules
- The parts on the circuit boards should be positioned so that when they are connected, the wires have as much shorter length, did not intersect, but did not lie parallel to each other. Here, the "beauty" of the assembled board is absolutely irrelevant and not important!
- When installing lamp circuits, all details are desirable in general solder directly to each otherwithout using wires or printed tracks (in the case of PCB mounting). As mounting "racks" (points of connection-soldering), the very conclusions of the lamp "panels", input and output connectors, transformers or other large-sized radio components fixed directly to the "chassis" (body) devices.
- All "common" wires each stage must be grounded at one point, preferably as close as possible to the input circuits of the stage. Then all these "common" points need put together, and to do this also at one point, the location of which is chosen, as a rule, experimentally, according to the minimum level of background or interference. And this one Common point can already be connected to the housing (chassis) of the entire electronic device, if this housing is metal. This will create a kind of protective "screen", which will also protect the device from external parasitic pickups (such interference can be created by a computer, LED or energy-saving lamps and other sources of impulse noise located nearby). If the body of the device is made of plastic, then such a protective screen can, if necessary, be made additionally from sheet metal or foil.
- When assembling high frequency devicesin (RF and microwave generators, frequency meters, receivers or transmitters) it is highly desirable to provide interstage partitions made of metal (foil) or place all cascades in separate shielding boxes (boxes).
- When developing printed circuit boards or direct mounting of parts in the electronics housing, on mounting "petals", you should adhere to rules for sequential arrangement of all active elements (lamps, transistors, microcircuits) in one row, one after another. The way they are usually drawn on the diagram.
- Input and output connectors it is also better to place it at the maximum distance from each other (on the front and back walls, for example). This will exclude possible unwanted interference between them.
- Carrying out the installation of electronic tubes, their heating circuits are best connected with wires twisted together in a "braid", like wires in a "twisted pair". This will help to reduce the influence of external interference and noise level (background with a frequency of 50 Hz, for example).
- All connecting wireslong, it is better to use shielded. The wires of the input, sensitive cascades are most often also used shielded. The shields (braiding) of these wires are connected to the "common" point of all the cascades.
- REA power supplies (pulse or with conventional transformers) should be located in the instrument case as far as possible from the electronic circuit, especially from its input stages. If this is not possible, then the power supply unit of the device can be separated from the circuit by a shielding partition or placed in a separate box.
- In all power circuits (primary and secondary windings, amplifier outputs and similar "power" circuits) it is advisable to include fuses for the appropriate voltage and amperage. This will allow you to avoid troubles in case of mistakes in installation, when setting up and connecting the device to the load.
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