Electronic products are often complex masses of circuitry. When you peel away the layers of a complex electronic product, common circuits, subsystems, and modules become visible. Common circuits are simple circuits that are easy to design, use, and test. The circuits listed here are common circuits commonly used in electronics.
resistor divider
One of the most commonly used circuits in electronics is the humble resistive divider. The resistive divider is a great way to drop a signal’s voltage into the desired range. Resistive dividers have the advantage of being inexpensive, easy to design, with few components, and taking up little board space. However, resistive dividers can add significant loading to a signal, dramatically altering the signal. In many applications this impact is minimal and acceptable, but designers should be aware of the impact a resistive divider can have on a circuit.
operational amplifier
Optical amplifiers are useful for buffering a signal while amplifying or dividing the input signal, which is handy when a signal needs to be monitored without being affected by the circuitry performing the monitoring. In addition, the gain and split options allow for a better detection or control area.
level change
Modern electronics are full of chips that require different voltages to operate. Low-power processors often run at 3.3 or 1.8 volts, while many sensors run at 5 volts. In order to connect these different voltages to a single system, the signals must either be scaled down or scaled up to the voltage level required for each chip. One solution is to use a FET based level shifter circuit or a dedicated level shifter chip. Level-shifting chips are the easiest to implement and require few external components, but they all have their quirks and compatibility issues with different communication methods.
filter capacitors
All electronic devices are susceptible to electronic noise, which can cause unexpected and chaotic behavior or halt the operation of the electronics altogether. Adding a filter capacitor to a chip’s power supply inputs can help eliminate noise in the system and is recommended for all electronic chips. Additionally, capacitors can be used to filter input signals to reduce noise on the signal line.
On / off switch
Power control of systems and subsystems is a common need in electronics. Several methods make it possible to achieve this effect, in particular using a transistor or a relay. Optically isolated relays are the most efficient and easiest way to implement an on/off switch on a sub-circuit.
voltage references
When precision measurements are required, a known voltage reference is often essential. Voltage references come in many forms. For much less precise applications, even a resistive voltage divider can provide a suitable reference.
power supplies
Each circuit requires the correct voltage to function, but many circuits require multiple voltages for each chip to function. It is relatively easy to go from a higher voltage to a lower voltage using a voltage reference for very low power applications or a voltage regulator for more demanding applications. When higher voltages are needed from a lower voltage source, a DC-DC boost converter will produce many common voltages and adjustable or programmable voltage levels.
Current source
Voltages are relatively easy to use in a circuit, but some applications require a fixed, constant current, such as B. for a thermistor temperature sensor or to control the output power of a laser diode or LED. Current sources are easily made from simple BJT or MOSFET transistors and some additional inexpensive components. High power versions of current sources require additional components and require greater design complexity to accurately and reliably control the current.
microcontroller
Almost all modern electronic products have a microcontroller at their core. While not a simple circuit module, microcontrollers provide a programmable platform on which to build an unlimited number of products. Low-power microcontrollers (typically 8-bit) power many devices, from microwave ovens to electric toothbrushes. More powerful microcontrollers are used to balance your car engine’s performance by controlling the air/fuel ratio in the combustion chamber while simultaneously performing other tasks.
ESD protection
An often overlooked aspect of an electronic product is ESD and voltage protection. When devices are used in the real world, they can be subjected to incredibly high voltages that can cause them to malfunction and even damage chips. Think of EDD as small lightning bolts attacking a chip. While the ESD and surge protection chips do their job admirably, basic protection comes from simple zener diodes placed at critical points in electronics, usually at critical signal paths and where signals enter a circuit or break it to the outside world leaving.