Digital circuits are commonly available in two families: transistor-transistor logic (TTL) and complementary metal-oxide semiconductor (CMOS). There are other families, such as emitter-coupled logic (ECL), but they are not as widely used. TTL devices are based on the bipolar junction transistor technology, while CMOS devices are based on the FET transistor technology. Table 1 shows […]
Most commercial servo drives accept PWM and direction signals as input. Also, many servo drives produce a PWM output voltage signal to the load such as a motor coil instead of a linearly variable output voltage. A PWM signal is a square-wave signal of fixed amplitude and frequency, but the width of the on and
A very common application of transistors is to construct drivers to drive motors. One such circuit is the H-bridge driver circuit, which is commonly used to drive motors in both directions. The circuit looks like the letter ‘H’ in circuit schematics, so it is called an H-bridge. An H-bridge circuit is constructed using four switching
The 555 timer chip (such as the NE555 8-pin chip from Texas Instruments) is an integrated circuit that uses a transistor, resistors, flip-flops, comparators, and capacitors to produce a variety of clock signals, including a fixed pulse, a periodic signal, and a frequency dividing signal. The NE555 can operate over a wide voltage supply range
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A SCR (silicon-controlled rectifier) is a three-terminal semiconductor device that behaves like a diode but with an additional terminal. The additional terminal is called a gate, and when a small current flows into the gate, it allows a much larger current to flow from the anode to the cathode (provided that the voltage between the
Metal-oxide semiconductor field effect transistors (MOSFETs) are the other family of transistors that are commonly used. The MOSFET is based on the original field effect transistor (FET) that was introduced in the 1960s. Similar to the BJT family, they are also three terminal devices, but they have different names for the terminals, and they operate
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The oscilator, which typically varies in frequency from Hz to a few MHz, is an electronic device used to convert DC energy into AC energy with a high frequency. An external signal source, such as an amplifier, is not required for an oscillator. Oscillators typically come in two varieties: sinusoidal and non-sinusoidal. While non-sinusoidal oscillators
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Overview of PMOS When p-type dopants are utilized in the gate area (the channel), the transistor is known as a p-channel metal-oxide semiconductor (pMOS) or PMOSFET. The device activates when the gate receives a negative voltage. PMOS or pMOS also referred to as P-type metal-oxide-semiconductor logic, is a category of the digital circuit built employing
In many situations, the raw output of the sensor may not be in a form suitable to be interfaced to a measurement device or an A/D convertor, and some form of signal conditioning is needed to be applied to the sensor output. These signal conditioning operations include filtering, amplification, or using a bridge circuit. In
There are a number of parameters that characterize sensors’ performance. The time-independent characteristics are called the static characteristics, while the time-dependent characteristics are called the dynamic characteristics. The static characteristics characterize the sensor output after it has settled due to changes in the physical quantity being measured. The dynamic characteristics describe the sensor characteristics from