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AC Power Control Circuits
AC Power Controls:  #'s - C      D - Z

Last Updated on: Tuesday, May 19, 2015 04:30 AM

Circuits Designed by Dave Johnson, P.E. :
  • 120 VAC Low Voltage Alarm  -  This circuit will activate a beeper alarm whenever the AC line voltage is less than 100vac. . . . [Circuit by David Johnson P.E.,  07/09/06]

  • 50ua Current Drives Solid State Relay Requires Only  -  Most solid state relays require at least 5ma and often more input control current, to fully turn on the device.  But such current levels often force battery powered circuits to use excessively large batteries.  The relay hobby circuit shown below demands only 50uA of input current . . . [Hobby Circuit designed by Dave Johnson P.E.,  06/03/00]

  • AC Line Powered LED Flasher  -  Some of the latest LEDs are amazing.  They can produce a surprising amount of light with very little current.  In the light flasher application shown below I take advantage of a nice surface mounted LED from King Bright.  This flasher circuit draws only about 3ua of average current from the AC power line to flash this green LED.  This flasher might be used as a power indicator light . . . [Hobby Circuit designed by Dave Johnson P.E.,  12/07/08]

  • AC Line Powered LED Strings  -  This shows 4 different ways to string white LEDs that are powered by a 120vac or 240vac power line.  This hobby circuit was designed by Ken Schultz.  . . . [Circuit by David A. Johnson P.E.,  12/18/04]

  • AC Line Under/Over Voltage Alarm  -  Power lines, which deviate much beyond normal voltages can damage expensive electronic equipment.  The circuit below sounds an alarm whenever the line voltage is higher or lower than normal.  I set the alarm limits at about +-15% from standard levels . . . [Hobby Circuit designed by Dave Johnson P.E.,  03/29/09]

  • AC Power Line High/Low Voltage Tester  -  If you wish to test a line-powered device under both a 15% high and a 15% low voltage condition, you can use the circuit below.  The circuit uses an 18v transformer with a 3 amp rating.  A double pole, double throw toggle switch then switches in the . . . [Circuit by David A. Johnson P.E.,  03/14/10]

  • AC Power Loss Alarm  -  I’ve been having a problem with my instant hot water system lately.  This system circulates electrically heated water throughout my house using a small pump.  The pump is wired into a ground fault interrupter (GFI) module.  Every now and then, the GFI trips, leaving me without hot water . . . [Circuit by David A. Johnson P.E.,  03/29/09]

  • Bi-Directional Charge Coupled Powers 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 . . . [Hobby Circuit designed by Dave Johnson P.E.,  06/03/00]

  • 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 . . . [Circuit by Dave Johnson P.E.,  06/03/00]

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

120 VAC Low Voltage Alarm -  This circuit will activate a beeper alarm whenever the AC line voltage is less than 100vac. . . . [Circuit by David Johnson P.E.,  07/09/06]

 

5.8 watt audio power amplifier -  A simple and very cheap audio power amplifier… [Name of Designer is not included]

 

50ua Current Drives Solid State Relay Requires Only -  Most solid state relays require at least 5ma and often more input control current, to fully turn on the device.  But such current levels often force battery powered circuits to use excessively large batteries.  The relay hobby circuit shown below demands only 50uA of input current . . . [Hobby Circuit designed by Dave Johnson P.E.,  06/03/00]

 

AC Line Powered LED Flasher -  Some of the latest LEDs are amazing.  They can produce a surprising amount of light with very little current.  In the light flasher application shown below I take advantage of a nice surface mounted LED from King Bright.  This flasher circuit draws only about 3ua of average current from the AC power line to flash this green LED.  This flasher might be used as a power indicator light . . . [Hobby Circuit designed by Dave Johnson P.E.,  12/07/08]

 

AC Line Powered LED Strings -  This shows 4 different ways to string white LEDs that are powered by a 120vac or 240vac power line.  This hobby circuit was designed by Ken Schultz.  . . . [Circuit by David A. Johnson P.E.,  12/18/04]

 

AC Line Powered LED Strings -  This shows 4 different ways to string white LEDs that are powered by a 120vac or 240vac power line. … [Designed by Ken Schultz, drawn by Dave Johnson 12.18.2004]

 

AC Line Under/Over Voltage Alarm -  Power lines, which deviate much beyond normal voltages can damage expensive electronic equipment.  The circuit below sounds an alarm whenever the line voltage is higher or lower than normal.  I set the alarm limits at about +-15% from standard levels . . . [Hobby Circuit designed by Dave Johnson P.E.,  03/29/09]

 

AC Power Line High/Low Voltage Tester -  If you wish to test a line-powered device under both a 15% high and a 15% low voltage condition, you can use the circuit below.  The circuit uses an 18v transformer with a 3 amp rating.  A double pole, double throw toggle switch then switches in the . . . [Circuit by David A. Johnson P.E.,  03/14/10]

 

AC Power Loss Alarm -  I’ve been having a problem with my instant hot water system lately.  This system circulates electrically heated water throughout my house using a small pump.  The pump is wired into a ground fault interrupter (GFI) module.  Every now and then, the GFI trips, leaving me without hot water . . . [Circuit by David A. Johnson P.E.,  03/29/09]

 

AC power supply -  I have done a lot of work with valves in recent years. For me valves have many advantages, least of all the price; since they are now "obsolete" it is quite easy to get hold of them for next to nothing at rally's and junk sales. I recently purchased a couple of hundred battery valves for less than SEK1 (GBœ0.10 US$0.15) each. … [Harry, SM0VPO Email: harold.lythall @ era.ericsson.se]

 

AC-power monitor uses remote sensing -  04/26/01 EDN Design Idea   The detection circuit in the Design Idea   "Circuit monitors ac-power loss" (EDN , Nov 24, 1999, pg 172) requires a physical connection with the mains to sense the power loss. The circuit in Figure 1 senses the power loss through the… [by Sanjay R Chendvankar, Tata Institute of Fundamental Research, Colaba, Mumbai, India]

 

AC-power your circuit without a transformer -  07/17/13  EDN Design Idea    Editor's Note: Here's another take on the transformerless AC line power supply, which finds use in some well-insulated, low-power devices. Our technical reviewer pointed out that Cac should be an X-rated safety type, and I think we'd both feel better if the ground symbol wasn't there!  SMPS circuits offer an efficient way to reduce AC from a mains source to any desired level for powering low-voltage circuits, though this comes at the cost of components such as control ICs, switching transistors, inductors, etc. Figure 1 shows a simple way you can use more common components to step-down and regulate the AC mains to the desired low DC voltage. … [by Raju Baddi]

 

Bi-Directional Charge Coupled Powers 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 . . . [Hobby Circuit designed by Dave Johnson P.E.,  06/03/00]

 

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 . . . [Circuit by Dave Johnson P.E.,  06/03/00]

 

Circuit Level-Shifts AC Signals -  10-Jul-03 EDN Design Idea   AC signals can emanate from many sources, and many of these sources are incompatible with the most popular interface voltages, such as TTL. A temptation always exists to capacitively couple the ac signals because capacitive couplin… [by Ron Mancini, Texas Instruments, Bushnell, FL]


AC Power Controls:  #'s - C      D - Z



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