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AC Power Control Circuits
Last Updated on:
Friday, October 16, 2009 03:41 AM |
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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)
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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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- 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.
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Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
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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) ….(designed by David A. Johnson) |
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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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Circuit Level Shifts AC Signals -(07/10/03 EDN Design Ideas / (added
12/04) 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 coupling strips
off the dc level. Capacitive coupling sometimes doesn't work, because the coupled
signal's voltage swings around ground, so you have to add dc offset to make...... |
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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) |
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Why Limit Your Power Supply's Input Range? -03/20/03 EDN Design Ideas /
(added 12/04)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.... |
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