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Control Circuits

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Last Updated: October 24, 2017 02:54 PM

Circuits Designed by Dave Johnson, P.E.

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 . . . Hobby Circuit designed by David Johnson P.E.-March, 2002

Provide 4- to 20-mA PWM control -  09/01/98 EDN-Design Ideas The circuits in Figure 1  and Figure 3 are useful when you use 4- to 20-mA current-loop signals to control a PWM signal.  In both circuits, the minimum pulse width corresponding to a 4-mA loop current) and the maximum pulse width corresponding to a 20-mA loop current) are independentlyFile has many circuits, scroll down __ Circuit Design by Tom Gay, Darmstadt, Germany

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Power Resumption Alarm -  Here is a simple power resumption alarm circuit that can be fixed inside the switch box itself.  It gives beeps when the power resumes after a power failure.  This circuit is ideal to monitor battery chargers, since the long duration power failure may sometimes remain unnoticed.  The circuit is too simple and derives power supply __ Designed by D Mohankumar

Power Resumption Alarm & Low-Voltage Protector -  The circuit described here protects your electrical appliances like AC motors from damage due to low voltage at power-on.  It remains standby without giving power to the load after power resumes....__ Electronics Projects for You

Power Saver -  NOTE : Must register on this site __ Designed by Published in Elecktor July/Aug, 2010

Power source is insensitive to load changes -  04/04/02 EDN-Design Ideas For the heating and cooling elements common in industrial systems, resistance is not a fixed quantity.  These elements include such devices as positive-temperature-coefficient heaters and thermoelectric coolers.  Their resistance can changethan 100% during operation, and the result is a change in power dissipation for elements receiving drive from a fixed voltage or current source __ Circuit Design by Ken Yang, Maxim Integrated Products, Sunnyvale, CA

Power supplies with automatic switchoff -  In principle it's easy to arrange an automatic switch-off system.  The difficult bit is deciding exactly what condition should cause the system to switch itself off.  So I suggest you think about that firstit's different for every system and not therefore something I can discuss here. __ Designed by Richard Torrens

Power USB VBUS in Autos with the LT8697 -  USB sockets appear in an increasing number of car models as portable devices become more ubiquitous.  The USB interface delivers power to portable devices via the 5V VBUS and ground lines.  Depending on the USB version and the portable device, the VBUS sources up to 2.1A.  In a car, this high VBUS current presents a challenge.  __ Linear Technology/Analog Devices App Note, Trevor Crane Design Engineer-Power Products Jul 15th 2013

Power-line outage flashes red alert -  06/13/02 EDN-Design Ideas This design idea expands on a circuit in a previous one to configure a power-outage detector with a flashing alarm(Figure 1, Reference 1].  The circuit plugs into a mains outlet and uses trickle-charged nickel-cadmium batteries.  The green-LED monitors the presence of line voltage.  The BZV55-C4V3 zener diode, D1 protects the batteries against overvoltage __ Circuit Design by Vasiliy Borodai, Zaporozhje, Ukraine

Power-On Time Delay Relay -  Here's a power-on time delay relay circuit that takes advantage of the emitter/base breakdown voltage of an ordinary bi-polar transistor.  The reverse connected emitter/base junction of a 2N3904 transistor is used as an 8 volt zener diode which creates a higher turn-on voltage for the Darlington connected transistor pair.  Most any bi-polar transistor may be used, but the zener voltage will vary from about 6 to 9 volts depending on the particular transistor used.  Time delay is roughly 7 seconds using a 47K resistor and 100uF capacitor and can be reduced by reducing the R or C values. __ Designed by Bill Bowden

Practical Circuitry for Measurement and Control Problems -  Linear Technology AN61 __ Designed by Jim WilliamsAug 1st, 1994

Pre-amp with tone control -  This a 2 in 1 circuit where 2 modules joined in one circuit.  With this circuit, you no longer use tone control circuit before your amplifier, but you can add an equalizer between this circuit and your amplifier circuit.  In this circuit, P1 is used to control the volume level, P2 to control Bass level and P3 controls Treble level.

Precision active load operates as low as 2V -  4-Aug-05 EDN-Design Ideas Self-powered active load matches low-voltage sources __ Circuit Design by Joel Setton, Crolles, France

Precision Attenuator with Digital Control -  This is a circuit for a low cost precision attenuator with digital control.  __ Electronics Projects for You

Precision Digital AC Power Controller -  SCRs and TRIACs are extensively used in modern electronic power controllers—in which power is controlled by means of phaseangle variation of the conduction period.  Controlling the phase angle can be made...__ Electronics Projects for You

Precision Temperature Controller Has Thermal-Gradient Compensation -  06/12/08  EDN-Design Ideas An electronic work-around cancels the effects of thermal gradients in the load's thermal impedances __ Circuit Design by W Stephen Woodward, Chapel Hill, NC

Precision Temperature Logger & Controller, Part 1 -  This Temperature Logger & Controller is based on the Dick Smith Electronics Q1437 digital thermometer.  It records & displays two temperature channels once a second on a PC over a period of up to 12 hours.  With appropriate thermocouples, temperatures from -200?C to +1300?C can be recorded, with the display range, resolution, and temperature program adjustable in real time while the data is being logged.__ SiliconChip

Preclude Common-Mode Conduction -  02/04/10  EDN-Design Ideas A crossover-control circuit prevents two ortransistors from powering on at once __ Circuit Design by Ken Herrick, Oakland, CA

Presure based hit switch -  This versatile hit switch is the electronics equivalent of a conventional switch.  It can be used to control the switching of a variety of electronic devices.  The circuit of the hit switch uses a piezoelectric diaphragm as the hit sensor.  A piezoelectric material develops electric polarization when strained by an applied stress.  The hit sensor makes use of this property.

Printer Port Controls A/D Conversion -  12/19/96 EDN-Design Ideas The circuit in Figue 1 uses a microcontroller (PIC16C71] as an A/D converter and a data organizer.  The circuit plugs directly into a PC printer port and needs no external power supply.  Under the control of the Borland C program in __ Circuit Design by Yongping Xia, Philips Lighting Electronics Co, Torrance, CA

Printer Port Controls Amplifier's Gain -  10/26/95 EDN-Design Ideas The circuit in Fig 1 lets you use a PC's printer port to set the gain of an inverting amplifier.  The circuit uses a 4-to-1 analog multiplexer, IC1, to select a pair of external resistors.  The multiplexer's connection scheme ensures that the on-state resistance of the analog switches does not affect the performance of the circuit.  The on-state series resistance is negligible in comparison with the high input impedance of the op amp.  The op amp's gain is, thus, the ratio of the two network resistances R2/R1 __ Circuit Design by Bogdan Manolescu, Gunicom Professional, Bucharest, Romania

Printer port controls video multiplexe -  08/01/96 EDN-Design Ideas The circuit in Figure 1 is a four-channel video-signal multiplexer.  Eight-bit binary data(of which only 3 bits are used] from a PC's parallel printer port controls the multiplexing operation.  The inputs for all the channel __ Circuit Design by Shyam Tiwari, SR&HPG, IGCAR, Kalpakkam, India

Printer Port Controls Video Multiplexer -  08/01/96 EDN-Design Ideas The circuit in Figure 1 is a four-channel video-signal multiplexer.  Eight-bit binary data (of which only 3 bits are used] from a PC's parallel printer port controls the multiplexing operation.  The inputs for all the channel __ Circuit Design by Shyam Tiwari, SR&HPG, IGCAR, Kalpakkam, India

Priority Switching from 12V Main Supply to 14.8V Battery Backup -  The LTC4417 connects one of three valid power supplies to a common output based on priority.  Priority is defined by pin assignment, with V1 assigned the highest priority and V3 the lowest priority.  A power supply is defined as valid when its voltage has been within its overvoltage (OV) and undervoltage (UV) window continuously__ Linear Technology/Analog Devices App Note, Feb 15th 2013

Processor Controls Watchdog -  01/18/96 EDN-Design Ideas The simple watchdog circuit in Figure 1 allows you to use the same line to provide additional information about the system's operation by closing or opening.    __ Circuit Design by Sergey Velichko, SCP, Boise, ID

Processor's PWM output controls LCD/LED driver -  27-May-04 EDN-Design Ideas The PWM(pulse-width-modulation] output available from many microprocessors is based on an internal 8- or 16-bit counter and features a programmable duty cycle.  It is suitable for adjusting the output of an LCD driver(Figure 1), a negative-voltage LCD driver(Figure 2], or a current-controlled LED driver(Figure 3] __ Circuit Design by Joe Neubauer, Maxim Integrated Products, Sunnyvale, CA

Program converts temperature from RTD sensor -  06/05/97 EDN-Design Ideas   100V, platinum resistance-temperature-detector(RTD]sensor provIdeas an accurate means of obtaining temperature readings.  Platinum sensors have a nonlinear resistance-vs-temperature characteristic; therefore, for __ Circuit Design by Robert Ruehle, Relco Products, Denver, CO

Programmable 3 phase Controller for ON/OFF Motor -  Automatic on/off controller for a 3-phase electric motor can be made with a programmable time switch.  In this case a maximum of eight time durations can be programmed.  The system has two...__ Electronics Projects for You

Programmable IR remote control -  NEC-SIRCS-JAPAN-RC5-SAMSUNG compatible, multiprotocol infrared remote control.  Replaces up to 6 existing remote controls into one.  With manual learning function, LED and/or LCD display...2V63V2, low power. __ Designed by Michel Bavin

Programmable LED -  Alex Inspired by various LED Throwies, blinking LEDs and similar instructables I wanted to do my version of an LED controlled by a microcontroller.  The idea is to make the LED blinking sequence reprogrammable.  This reprogramming can be done with __ Designed by Radio LocMan

Programmable LED Flashers -  LED goes to steady state after a preset number of flashes; Two simple, wide supply range operating circuits __ Contact: Flavio Dellepiane, fladello @ tin.it

Proportional Radio Remote Control -  When I wrote the ZN414 radio IC receiver projects I made reference to a future proportional radio control encoder and decoder project that was to follow.  Well here it is.  It matters not what medium this encoder and decoder uses.  You may use your own Amateur Radio transmitter/receivers, although I would not recommend you having your $250 70cm handheld whizzing around the skies at 120Km/H.  A simple TX and RX is all that is needed but they are not covered in this project.  I will just cover the proportional encoder and decoder. __ Designed by Harry Lythall-SM0VPO

Proportional-Ac-Power Controller Doles Out Whole Cycles Of AC Line -  4-Sep-08 EDN-Design Ideas A pulsed current mirror comprising discrete transistors drives LEDs from a low voltage, avoiding thermal runaway __ Circuit Design by Richard Rice, Oconomowoc, WI

Protect system from overheating -  11/08/01  EDN-Design Ideas The two-chip circuit in Figure 1 provIdeas fan control and overtemperature warning and shutdown signals to protect systems from excessive heat.  The circuit monitors the temperature of the pc board and the die temperature of a CPU, an __ Circuit Design by Kerry Lacanette, Maxim Integrated Products, Sunnyvale, CA

Protected 1A Automotive Solenoid Driver with Overvoltage Shutdown -  The LT1910 is a high side gate driver that allows the use of low cost N-channel power MOSFETs for high side switching applications.  It contains a completely self-contained charge pump to fully enhance an N-channel MOSFET switch with no external components.  __ Linear Technology/Analog Devices App Note, Apr 5th 2010

Protection from Overvoltage & Overcurrent -  The LTC4361 overvoltage/overcurrent protection controller safeguards 2.5V to 5.5V systems from input supply overvoltage.  It is designed for portable devices with multiple power supply options including wall adaptors, car battery adaptors and USB ports.  The LTC4361 controls an external N-channel MOSFET in series with the__ Linear Technology/Analog Devices App Note, Apr 26th 2010

Protection of USB Port from Overvoltage & Overcurrent -  The LTC4362 monolithic overvoltage/overcurrent protector safeguards 2.5V to 5.5V systems from power supply overvoltage.  It is designed for portable devices with multiple power supply options including wall adaptors, car battery adaptors and USB ports.  __ Linear Technology/Analog Devices App Note, Jul 8th 2011

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Control Circuits:   #'s - A       B - C       D - G        H - L       M - P        Q - S        T - U        V - Z


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