This converter uses a low-pass filter instead of the usual tuned circuit so the only tuning required is with the receiver. The dual-gate MOSFET and FET used in the mixer and oscillator aren"t critical. Any crystal having a frequency compatible with the receiver tuning range may be used. For example, with a 3500 kHz crystal, 3500 kHz on the receiver dial corresponds to zero kHz; 3600 to 100 kHz; 3700 to 200 kHz, etc..
Because power MOSFETs offer high power gain at both audio and radio frequencies, they are useful in many areas of radio-circuit design. For rf applications, a MOSFET"s large safe operating area, V0 s vs ! 0, protects it against damage from reflected rf energy. As a modulator, a MOSFET"s transfer linearity aids fidelity. In the suppressed-carrier modulator, an rf signal is applied to the primary of transformer Tl, whose secondaries provide equal-amplitude,.....
A 40673 dual-gate MOSFET is matched to a crystal filter at 45 MHz. The filter impedance is around 2kQ...
This inverter can deliver .high-voltage ac or de, with a rectifier and filter, up to several hundred volts. The secondary and primary of T1-a 12.6 to 440 V power transformer, respectively-are reversed; e.g., the primary becomes the secondary and the secondary becomes the primary. Transistors Q1 and Q2 can be any power FET. ..
A 30- to 50-cm whip antenna provides reception from 10 kHz to over 220 MHz. Tl, a dual-gate MOSFET, provides low noise, high-input impedance, and high gain,..
This circuit operates from a 16- to 50-V supply. Adding the buffer circuit (within the dashed lines) offe..
The second gate (G2) of a MOSFET can be used to incorporate a crystal oscillator into the same stage as a frequency mixer. Although old hat with tubes, this scheme is seldom seen in dual-gate MOSFET circuitry. L3, 03, and XI form the crystal oscillator, and T2 is an IF output transformer. T1 and 01 are tuned to the converter input frequency. ..
Positive output step-up and step-down de-de converters have a common limitation in that neither can handle input voltages that are both greater than or less than the output. For example, when converting a 12-V sealed lead/acid battery to a regulated +12 V output, the battery voltage might vary from a high of 15 V down to 10 V. By using a MAX641 to drive separate P-and N-cbannel MOSFETs, both ends of the inductor are switched to allow noninverting buck/boost operation. ..
Biasing methods for an N-channel MOSFET to form a unity-gain noninverting amplifier..
The LTC10432 switched-capacitor building block provides nonoverlapping complementary drive to the Ql to Q4 power MOSFETs. The MOSFETs are arranged so that Cl and C2 are alternately placed in series and then parallel. During the series phase, the + 12 V battery"s current flows through both capacitors, charging them, and furnishing load current. During the parallel phase, both capacitors deliver current to the load. Ql and Q2 receive similar drive from pins 3 and 11. The.....
A charge pump is a simple means of generating a low-power voltage supply of opposite polarity from the main supply. The 74Cl4 IC is a self-oscillating driver for the MOSFET power switch. It produces a pulse width of 6.5 p,s at a repetition frequency of 100 kHz. When the MOSFET device is off, capacitor C is charged to the positive supply. When the power through the MOSFET switches on, C delivers a negative voltage through the series diode to the output. ..
This circuit, produces a soft turn-on for halogen lamp filaments upon powering up. MOSFET used is a BUZ10, which has 0.2 Rm on...
A bridge rectifier and 12-volt regulator powers the MOSFET sensing circuit. The unregulated output of the bridge rectifier operates the drain solenoid via switch SI. The sensor itself is built from two electrodes, one made of copper, the other of lead. In combination with the liquid trapped by the sensor, they form a miniature lead-acid cell whose output is amplified by MOSFET Ql. The maximum output produced by our prototype cell was about 50 µ. MOSFET Ql serves as the.....
A power MOSFET and a quad exclusive-OR oscillator makes an effective solid-state relay. Figure 75-5(a)"s capacitively iso..
This smoke detector uses a MEM 817 p-channel enhancement mode MOSFET as its buffer amplifier. Operation of the sensor is based on a decrease in the current when smoke enters the chamber, thereby causing a negative voltage excursion at the gate of the buffer MOSFET. ..
An MPF102 FET oscillator drives a dual-gate MOSFET buffer. The MPF102 is configured as a Hartley oscillator...
Operating at around 1.1 GHz, the detector senses field disturbance in the neighborhood of the antenna. The Doppler signal from detector D1 is amplified and drives a power MOSFET switch...
A MOSFET is used as a wideband buffer amplifier. T1 is wound on a toroid of approximately /f diameter, with material suitable for frequency (usually 1- to 20-MHz range). The turns ratio should be about 4:1 depending on load impedance. Typically, at 4 MHz, there are 18 turns on the primary, ..
The use of a double-tuned input and a single-tuned output yield superior RF selectivity to that of equivalent..
Has an input resistance of 1-MO, a bandwidth from de to about 35 MHz, and a gain of 10 times. Lowfrequency gain is provided by a CA3130 BiMOS op amp operated as a single-supply amplifier. High-frequency gain is provided by a 40673 dual-gate MOSFET. ..
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