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Transistor
Circuits,
Page 4
Transistors:
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Last Updated on:
Friday, June 04, 2021 01:53 PM |
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Circuits Designed by Dave Johnson, P.E. : |
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- CIRCUIT
PROTECTS FROM BATTERY POLARITY REVERSAL
This simple circuit can protect a sensitive electronic circuit from an accidental
connection of a battery with a reversed polarity. The N-channel FET connects
the electronic device to the battery only when the polarity is correct. The
circuit shown was designed for a device powered from a single 1.5 volts button cell
battery. However, the circuit will operate with higher voltages as well.
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- CHARGE COUPLED
BI-DIRECTIONAL POWER MOSFET RELAY
The circuit uses an inexpensive C-MOS inverter package and a few small capacitors to
drive two power MOS transistors from a 12v to 15v supply. Since the coupling
capacitor values used to drive the FETs are small, the leakage current from the
power line into the control circuit is a tiny 4uA. Only about 1.5mA of DC is needed
to turn on and off 400 watts of AC or DC power to a load.
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Links to electronic circuits, electronic schematics and designs for engineers, hobbyists, students & inventors:
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Build A One Transistor FM Radio - (project added 6/07) |
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Charge Coupled Bi-Directional Power Mosfet Relay - The circuit uses an
inexpensive C-MOS inverter package and a few small capacitors to drive two power MOS
transistors from a 12v to 15v supply. Since the coupling capacitor values used to
drive the FETs are small, the leakage current from the power line into the control
circuit is a tiny 4uA. Only about 1.5mA of DC is needed to turn on and off 400 watts
of AC or DC power to a load. Published in Electronic Design, Nov. 8, 1990. ….
[Designed by David A. Johnson] |
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Charge Pump Efficiently Divides Supply Voltage - This circuit uses a few
FETs and logic devices to down convert a DC voltage to about one half its value ….
[Designed by David A. Johnson] |
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Cheap Pushbutton replaces Rotary Switch - 26-Oct-00 Issue of EDN-Design
Ideas....The problem of setting any one of four modes of aµC-operated process has a
straightforward solution Have theµC check the states of some 4 bits of aµC.…
[Design Idea by Abel Raynus, Armatron International Inc, Melrose, MA] |
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Circuit Detects Current Pulses - 01/06/94 EDN-Design Ideas....The pulse
detector provides a visible indication of positive and negative current pulses. The
pulses amplitudes can vary from20 to150 mA. The pulses durations can range from10 to40
msec, and their repetition rate can span40 to180 pulses/minute.... [Design Idea by
Richard McGillivray, Grey Bruce Regional Health Centre, Owen Sound, Ontario, Canada] |
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Circuit optimizes PhotoTransistor Bandwidth - 04/09/98 EDN-Design Ideas....A
simple circuit can improve the dynamic performance of a phototransistor for use in
low- to medium-speed applications as fast as 100 kbps, such as optical isolation of an
RS-232C serial line (Figure 1). In low-cost applications....several circuits included,
scroll the find this one.... [Design Idea by David Magliocco, CDPI, Scientrier,
France] |
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Circuit Protects from Battery Polarity Reversal - This simple circuit can
protect a sensitive electronic circuit from an accidental connection of a battery with
a reversed polarity. The N-channel FET connects the electronic device to the
battery only when the polarity is correct. The circuit shown was designed for a
device powered from a single 1.5 volts button cell battery. However, the circuit
will operate with higher voltages as well. …. [Designed by David A. Johnson] |
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Circuit provides ISFET-sensor bias - 10-Jun-04 Issue of EDN ISFETs
(ion-sensitive field-effect transistors] are useful for measuring the acidity of
fluids. Accurate measurements require that the ISFET's bias conditions (ID and VDS] be
held constant while the gate is exposed to the fluid under test. The acidity of the
fluid changes the channel width, resulting in a gate-source voltage, VGS, that is
proportional to the fluid's pH.... [Design Idea by Brian Harrington, Analog Devices,
Wilmington, MA] |
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Circuit reduces negative voltage stresses on control IC - 18-Apr-02 Issue of
EDN In a synchronous, buck switching power supply, the two FETS and the output
inductor meet at the phase node (Figure 1). The phase node often connects directly to
the control IC. The voltage on this node swings from the input voltage to some voltage
lower than ground. If the voltage goes too far below ground, the ESD structures or
other circuitry within the control IC can become forward-bia.... [Design Idea by
Michael Day, Texas Instruments Inc, Dallas, TX] |
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CMOS DACs act as digitally controlled voltage dividers - 26-Jun-08 Issue of
EDN You can employ a DAC to operate as a digitally programmable resistor from a
single supply.... [Design Idea by John Wynne and Liam Riordan, Analog Devices,
Limerick, Ireland] |
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CMOS Gate Implements Reverse Phase Control - 05/21/98 EDN-Design
Ideas....The circuit in Figure 1 implements a "reverse" phase control, using only a
single CMOS 4001 quad NOR gate. The circuit is known as a reverse phase control
because, unlike with common triac or SCR controls, conduction begins at the zero
crossing of the ac sine wave. Timing of the turn-off point....File has seeveral
circuits, scroll down.... [Design Idea by JC Johnson, Lithonia Lighting, Decatur, GA] |
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CMOS hex inverter generates low-distortion sine waves - 9-Jun-05 Issue of
EDN Audio signal source uses hex inverter and handful of passives.... [Design
Idea by Al Dutcher, West Deptford, NJ; Edited by Brad Thompson and Fran Granville] |
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Considerations for Driving Power MOSFETs in High-Current, Switch Mode Regulators -
Microchip Application Note Published 12-Nov-02 (app note added 2/06)
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Transistors:
#'s A
B-C D-G
H-I J - O
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T - Z
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