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Modulators Circuits Page 5
Modulators: #-E F-L
M-N O-P Q-Z
Last Updated on:
Wednesday, December 31, 2008 03:16 PM |
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| Links to electronic circuits, electronic schematics, designs for engineers,
hobbyists, students & inventors: |
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RF Modulator: (circuit / schematic added 2/03) |
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Servo Pulse to PWM: converter connects an H-Bridge to radio control receivers or robotic circuits. (added 1/05) |
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Simple Circuit Provides Efficient PWM: 02/18/99 EDN-Design Ideas / (added 2/06) You often need to control the duty cycle of a
square wave. The circuit in Figure 1 works from a single 5V supply at a frequency of 100 kHz. With minor component changes, you can configure it for a range of frequencies. The circuit consists of
a ramp (sawtooth) oscillator and a comparator. The circuit compares the ramp to an externally applied voltage, VCNTRL. When VCNTRL is greater than the ramp voltage, the PWM output is 5V. The
sawtooth oscillator consists of a current source (R1, R2, R3, and Q1), a timing capacitor (C1), and the oscillator-control circuitry (R4, R5, R6, and IC1A). The oscillator-control circuitry sets
the upper and lower voltages of the timing capacitor at 3 and 1V.... |
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Simple nanosecond width pulse generator provides high Performance: 11/11/04 EDN-Design Ideas / (added 5/05) |
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Simple PWM ADC is Surprisingly Accurate: 06/09/94 EDN-Design Ideas / (Electronic Circuit diagram added 03/03) The reference
voltage in Fig 1a's simple rail-to-rail PWM ADC is the only critical component. The input-voltage range extends from ground to the power rail which also acts as the reference. The circuit is
essentially a variation on the classic dual-slope integrator, the slopes being proportional to VIN and VREF-VIN. The circuit works well in µP-based systems that have the spare capacity to perform
the mark/space measurement and the necessary calculations..... |
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Small FM Transmitter: (circuit added 7/02) |
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ST6: UNIVERSAL MOTOR Control EVALUATION BOARD: The UMC01EVAL Evaluation Board is designed for a very low-cost phase control
system based on the 8-bit ST62T00C microcontroller. It can be used to control a universal motor powered by a 230 V / 50 Hz mains supply. (circuit design added 3/05) |
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Stereo Ducker: (Electronic circuit added 7/03) |
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Strain Gage Measurement using an AC Excitation: AN-683-Analog Device Application Notes (app note added 2/06)
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Subcarrier Adapter : Listen to those hidden FM transmissions (added 2/06) |
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Synchronous
Modulator: This unique circuit uses a very small amount of battery current and has excellent carrier suppression. Its only shortcoming is that you must limit the input signal to 0.7 Vp-p
in order to prevent distortion. To use higher input voltages, replace Q3 with a JFET. A MOSFET doesn’t do as well as an NPN transistor. Designed by Andrew R. Morris (Circuit / schematic design added 6/06) |
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Synchronous Modulator-1: This is an OpAmp version of the synchronous modulator I submitted earlier. It has more consistent performance over varying power supply voltage than the discrete
version, but it still has the 0.7 Vp-p limitation on the maximum input voltage. You should use a JFET or a CMOS switch in place of Q1 if you need to accommodate a higher input voltage. Also, a low
pass filter needs to be added after the output of this circuit, where the discrete version had one built in. Designed by Andrew R. Morris (Circuit / schematic design added 6/06) |
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Synchronous System Measures µΩs: AN-306-Analog Device Application Notes (app note added 2/06) Synchronous Detection
Scheme Measures Low Resistances |
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Transistor Pair Lowers PWM IC's Start up Current: 03/18/99 EDN-Design Ideas / (added 2/06) An auxiliary winding usually
provides power for the popular UC384X-based offline switch-mode power supplies (SMPSs). This winding feeds the main PWM controller during steady-state operation. However, the controller always
needs a small start-up current, which clearly plagues the efficiency in very low-power standby SMPSs with POUT =500 mW, for example. Any wasted source power, such as for the start-up network and
controller supply, adds to the power drawn from the mains and significantly degrades the overall efficiency. Obtaining an acceptable efficiency at high line voltage represents a tough design task.
Some tricks totally stop the start-up current by using a high-voltage bipolar or MOSFET (Reference 1). However, the.... |
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TV Modulator: This circuit uses an MC1373 to form a TV video modulator (Electronic circuit added 5/02) |
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Variable Range PWM A/D for COP820CJ: National Semiconductor - Application Note (app note added 2/06) |
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Variations on the PWM DC Motor Speed Control: (added 9/02) |
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Voltage Controlled Mixer with Modulator: (Electronic circuit added 7/03) |
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Waveform Generator Demodulates FM Signals: 10/10/96 EDN-Design Ideas / (added 2/06) / The circuit in Figure 1 uses the
phase-detector signals of a precision waveform-generator IC to perform FM demodulation. In a standard application, the IC's phase-detector input and output synchronize the chip's output frequency
to that of an applied signal. If the signal is FM, you can extract the demodulated signal from the phase-detector output. The waveform generator IC's phase-detector input (PDI)
typically receives the phased-lock signal. The phase-detector output (PDO) then produces a duty-cycle-modulated train of rectangular current pulses that alternate between 0 and 500 mA. The duty
cycle approaches 0% when PDI and the chip output (equivalent to the internal oscillator output) are in phase, 100% when they differ by 1808, and 50% as they approach.... |
