Abstract: With a few op amps and some external components, you can build a pulse generator with variable frequency and duty cycle.
The natural choice for generaTIng a pulse of variable frequency and duty cycle is a good bench-top pulse generator. If you don't have a generator or must build one into your system, however, you can do it with a few op amps and some external components (Figure 1).
Figure 1. This simple and versaTIle pulse generator includes only 15 components.
U1 and Q1 form a voltage-controlled oscillator (VCO) with a square-wave output and a triangle-wave output. The square wave feeds back to control the charge and discharge of integraTIng capacitor C1, and is also useful as a sync-signal output. The triangle wave drives the non-inverTIng input of duty-cycle controller U2-2. R2 fully adjusts the output duty cycle (from 0% to 100%) by controlling U2-2's inverting input. U2-2 generates the output signal directly.
U2-1 buffers R1's wiper voltage, which controls the VCO frequency. A change in supply voltage (V +) varies the output swing without effecting the output frequency or duty cycle, and the circuit operates equally well with a single supply or with dual supplies. The frequency range shown is 20Hz to 13kHz, but you can modify that range by changing the value of C1. The dual op amps (designed for controlling power amplifiers) are chosen for their high output drive, rail-to-rail input and output capabilities , single-supply operation, and exceptional open-loop behavior.
A similar version of this article appeared in the January 20, 2003 issue of EET magazine.
2. The maximum allowable long-term operating temperature of the cable electrical conductor is 70 ℃.
3 The working temperature during cable laying shall not be lower than 0 ℃. If the natural environment temperature is lower than 0 ℃, the cable shall be heated.
4 The strongly recommended allowable bending radius of cable is below:
The unarmoured cable shall not be less than 6 times of the cable diameter;
Armored cable or copper foil shielded cable shall not be less than 12 times of cable diameter;
The shielded Flexible Cable shall not be less than 6 times of the cable diameter.
5 Productive cable model 2-61 cores
6 Control cables are generally laid in rooms, cable trenches, pipelines and other fixed sites.
The natural choice for generaTIng a pulse of variable frequency and duty cycle is a good bench-top pulse generator. If you don't have a generator or must build one into your system, however, you can do it with a few op amps and some external components (Figure 1).
Figure 1. This simple and versaTIle pulse generator includes only 15 components.
U1 and Q1 form a voltage-controlled oscillator (VCO) with a square-wave output and a triangle-wave output. The square wave feeds back to control the charge and discharge of integraTIng capacitor C1, and is also useful as a sync-signal output. The triangle wave drives the non-inverTIng input of duty-cycle controller U2-2. R2 fully adjusts the output duty cycle (from 0% to 100%) by controlling U2-2's inverting input. U2-2 generates the output signal directly.
U2-1 buffers R1's wiper voltage, which controls the VCO frequency. A change in supply voltage (V +) varies the output swing without effecting the output frequency or duty cycle, and the circuit operates equally well with a single supply or with dual supplies. The frequency range shown is 20Hz to 13kHz, but you can modify that range by changing the value of C1. The dual op amps (designed for controlling power amplifiers) are chosen for their high output drive, rail-to-rail input and output capabilities , single-supply operation, and exceptional open-loop behavior.
A similar version of this article appeared in the January 20, 2003 issue of EET magazine.
Control cable is a kind of cable. It is used for control and monitoring circuits and protection circuits with AC rated voltage of 450V/750V and below. Shielded control cables are widely used in power plants and power stations due to their good shielding performance. They are intended to be laid indoors, in cable trenches, in pipelines, directly buried, in shafts and other fixed places that can withstand greater mechanical tension.
Feature
1. DC rated current Uo/U is 450/750V2. The maximum allowable long-term operating temperature of the cable electrical conductor is 70 ℃.
3 The working temperature during cable laying shall not be lower than 0 ℃. If the natural environment temperature is lower than 0 ℃, the cable shall be heated.
4 The strongly recommended allowable bending radius of cable is below:
The unarmoured cable shall not be less than 6 times of the cable diameter;
Armored cable or copper foil shielded cable shall not be less than 12 times of cable diameter;
The shielded Flexible Cable shall not be less than 6 times of the cable diameter.
5 Productive cable model 2-61 cores
6 Control cables are generally laid in rooms, cable trenches, pipelines and other fixed sites.
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