AC Power Control Electronic Circuits

AC Power Control Circuits
Last Updated on: Monday, October 03, 2011 06:07 PM

Circuits Designed by Dave Johnson, P.E. :

AC Line Powered LED Strings
This shows 4 different ways to string white LEDs that are powered by a 120vac or 240vac power line. The circuit was designed by Ken Schultz. (added 12/04)

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.

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, the circuit can control about 600 watts of power to load while providing full isolation and transient protection.

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

AC Line Powered LED Strings - This shows 4 different ways to string white LEDs that are powered by a 120vac or 240vac power line. The circuit was designed by Ken Schultz…. [Hobby Corner Circuit by Dave Johnson]

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…. [Designed by David A. Johnson]

Circuit level-shifts ac signals - 10-Jul-03 Issue of EDN 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.... [Design Idea by By Ron Mancini, Texas Instruments, Bushnell, FL]

Line Input for Zoom H2 - ….must register on this site... [Published in Elecktor July/August 2010]

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, the circuit can control about 600 watts of power to load while providing full isolation and transient protection. Published in Electronic Design, Dec 2, 1996. …. [Designed by David A. Johnson]

Why limit your power supply's input range? - 20-Mar-03 Issue of EDN Taking only a cursory look at the input-voltage ratings of your power-supply IC can limit the usable input-voltage range. With careful examination of an IC's operating specifications and circuit topology, you may be able to work around that input-voltage limitation. For instance, The data sheet for TI's (www.... [Design Idea by Michael Day, Texas Instruments, Dallas, TX]

AC Power Control Circuits