1.White LED Strings of AC Powered
A while back a guy by the name of Ken Schultz sent me a simple drawing of how he connected a string of 30 LEDs, to make a nice under the counter accent light, powered by 120vac. He wired the strings in two series sections of 15 LED each, but wired in opposite directions. He then used just one capacitor to limit the AC current through the two stings. I looked at the circuit and decided that it seemed quite reasonable. The only change I decided to make was to add a metal oxide resistor in series with the capacitor, to act as fuse and to limit the peak current, should there be a voltage spike on the AC line. With the two strings of 15, the current is first pumped through one series string, then as the AC line polarity changes, it flows through the second string. Since the capacitor acts as a constant current source, you can use other string numbers. The capacitor value shown keeps the current limited to about 20ma for the LEDs. In Europe and Australia, where the line frequency is 50Hz, you may see a noticeable strobing of the LEDs, if there is substantial separation between the two different polarity strings.
2. 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
2.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.
2. 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
2.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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