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Power Control Circuits
#'s - D      E - Z


 

Last Updated: October 24, 2017 02:55 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

Solid State Relay Requires Only 50ua Drive Current - This circuit demands a control current that is 100 times smaller than that needed by a typical optically isolated solid state relays.  It is ideal for battery-powered systems.  Using a combination of a high current TRIAC and a very sensitive low current SCR. . . Circuit by David A. Johnson P.E.-June, 2000


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

Emergency Backup Lamp-  This back-up lamp stays off as long as light falls on the CdS photocell from either the NE-2 or from room ambient light.  So, if the power fails at night, the lamp will light.  The 6 volt lamp should be directed away from the photocell __ Contact:  Charles Wenzel of Wenzel Associates, Inc.

Ensure Safety In Power-On Operation-  04/24/03  EDN Design Ideas:  Buck converter handles battery-backup system - Computers find universal use in industrial-control systems.  During power- and start-up sequences (booting], the outputs of such control systems may yield uncontrolled pulses before the __ Circuit Design by Jean-Bernard Guiot, DCS AG, Allschwil, Switzerland

Increasing output voltage & current range using series-connected isolated μModule converters-  EDN Design Ideas:  10/02/2015  Stack isolated converters to increase output voltage __ Circuit Design by LTC Design Note

 
Isolated Driver Forms Solid-state Breaker-  03/02/98 EDN Design Ideas:  (File contains many circuits, please scroll to find this one) This circuit allows standard TTL logic levels to safely drive a high-power dc load, circuit provide as also overcurrent circuit breaker functionality. __ Circuit Design by Bob Watson, Corley Manufacturing Co, Chattanooga, TN

Load Simulator Maintains Constant Power-  04/11/96 EDN Design Ideas:  The circuits in Figures 1 and 2 show how you can emulate a constant-power load for cases when a simple load resistor is unacceptable.  For example, using a simple resistor as a load is unacceptable for applications that require you to accurately monitor generated or consumed power.  One such application is in battery-energy measurement.  You measure battery energy density (watts/hour) by measuring the total output power (W=VxI) over time.  This task is relatively simple if you use an automated system to take frequent and periodic measurements of the discharge current and battery voltage while keeping track of time. __ Circuit Design by Khy Vijeh, Analog Devices, Santa Clara, CA

Load Switcher Draws Only 6 A-  07/04/96 EDN Design Ideas:  Although it draws only 6 A, the circuit in Figure 1 enables a small ac signal as low as 1 mV to switch relatively large load currents.  The circuit takes advantage of the IC's very low quiescent current, which, at 1.2 A maximum per amplifier, is less than the self-discharge of a typical battery.  This current can flow through R1 without turning on Q1.  When you operate the circuit with a sensing coil (Figure 1) and stimulate it with a magnet, the circuit performs the function of a reed switch but with greater sensitivity.  Other applications include alarm systems, bipolar threshold sensing, and audio volume switching. __ Circuit Design by Douglas Dwyer, Frequency Precision Ltd, Okehampton, UK, and Nigel Brook, Maxim Integrated Products, Reading, UK

Low-side switch with fast turn-off for inductive loads-  06/23/14  EDN Design Ideas:  Ditch the freewheeling diode if you want fast turn off.  This Design Idea is able to turn off inductive loads at a very fast rate.  When connected to a load (here 15mH + 10Ω) , the modified freewheeling path in the clamping circuit based around M2 reduces the turn off time to 450s.  A simple freewheeling diode in place of the clamping circuit takes about 4ms to turn off the load. __ Circuit Design by Deivaraja Ramasamy

LTC Design Note: Increasing output voltage & current range using series-connected isolated μModule converters-  EDN Design Ideas:  10/02/2015  Stack isolated converters to increase output voltage __ Circuit Design

Mains Synchronization Has Two Separate Outputs for Each Half-Period-  03/22/13  EDN Design Ideas:  Generate independent short pulses at positive- and negative-going AC mains zero crossings.  Often a measurement of weak signals has to be performed in the presence of strong interference from the ac power mains.  If the interfering signal cannot be filtered out, then you can still obtain a clean result by making two consecutive measurements separated in time by an odd number of half-periods of the mains and calculating the average of the two measurements.  The interfering signals have opposite polarities in consecutive measurements, and averaging cancels them out.  If you average several consecutive pairs of measurements, the results will improve still further. __ Circuit Design by Dusan Ponikvar

Microcontroller Watches, Controls AC Power-  06/22/95 EDN Design Ideas:  Circuit allows an isolated microcontroller to both sense and control ac power to an externally plugged-in device - For monitoring and controlling a power circuit from a microcontroller (C) , Fig 1 replaces the conventional technique of a low-value resistor and differential amplifier (with gain set for the expected current value).  A control line turns TRIAC Q1 on and off via optoisolator IC2.  When an appliance is plugged into J1 and turned on, the voltage drop across Q1 is independent of the current value and sufficient to turn on optoisolator IC3.  The phototransistor current of IC3 charges C1to a logic 1, which is sensed by the C. __ Circuit Design by Samuel Kerem, Infrared Fiber Systems, Silver Spring, MD

Novel controls AC power-  01/07/99 EDN Design Ideas:  (Several Circuits in File.  Scroll to find this one) The simple and inexpensive power-control circuit in Figure 1 uses a readily available fan regulator with built-in phase control.  Such fan regulators are limited to approximately 100W.  The circuit in Figure 1 adds two SCRs and a few components   Page includes several designs. __ Circuit Design by Narendra Paranjape, Tata Chemicals Ltd, Mithapur, India

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 change more than 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

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

Pushbutton switch controls power supply & C-  09/25/97 EDN Design Ideas: Switching handheld units on and off with a pushbutton switch is a desirable feature.  Thus, switching-regulator/ controller ICs for battery-powered applications provide a logic input to switch the device to a shutdown mode.  This type of shutdown pin can require additional components __ Circuit Design by Greg Dittmer, Linear Technology Corp, Milpitas, CA

Short DC power-line pulses afford remote control-  10/25/01 EDN Design Ideas:  If you face the challenge of adding a second, independently controlled light source to an existing ceiling lamp controlled by a wall switch, you may find that stringing a second power line is impossible.  First, you can replace the wall switch by the circuit in Figure 1.  Pushing the on switch S1 or S2 for approximately 1 sec inserts the 12V zener diodes D1 or D2 in series with the __ Circuit Design by Tom Hornak, Portola Valley, CA

Simple Circuit disconnects load-  02/17/00  EDN Design Ideas:  Placing a load-disconnect circuit on the output of a bootstrapped step-up regulator allows the regulator to start with load currents much higher than would otherwise be possible ( Figure 1).  During shutdown, the disconnect completely isolates the battery __ Circuit Design by Larry Suppan

Simple Circuit Disconnects Load From Battery-  03/14/96 EDN Design Ideas:  To prevent battery damage, the circuit in Figure 1 disconnects the load at a predetermined level of load voltage.  This load voltage, VTRIP, is closely proportional to the battery voltage.  R1 and R2 determine the level of VTRIP  that corresponds to voltage of 1.15V at pin 3 of IC1.  A voltage of 1.15V at pin 3 of IC1 causes the internal comparator to trip.  Thus, VTRIP=1.15 (R1+R2) /R1 __ Circuit Design by Michael Keagy, Maxim Integrated Products, Sunnyvale, CA

Smart switch cuts transformer turn-on current-  04/23/98 EDN Design Ideas:    NOTE: File contains multiple circuits scroll to find this circuit. Transformer-core saturation can cause inexplicable fuse blowing, system crashes, or premature switch and relay failure.  When a core saturates, it loses its inductive characteristics; primary winding __ Circuit Design by Robert Lindsey, Hansvedt EDM, Urbana, IL

Soft Start for Power Amps-  Although the soft start circuit can be added to any sized transformer, the winding resistance of 300VA and smaller transformers is generally sufficient to prevent a massive surge current.  Use of a soft start circuit is definitely recommended for 500VA and larger transformers __ Designed by Rod Elliott  ESP

Solid State Relay Requires Only 50ua Drive Current-  This circuit demands a control current that is 100 times smaller than that needed by a typical optically isolated solid state relays.  It is ideal for battery-powered systems.  Using a combination of a high current TRIAC and a very sensitive low current SCR. . . Circuit by David A. Johnson P.E.-June, 2000


Power Control Circuits#'s - D      E - Z

 


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