Tag Archives: Triac

Simple SSR has zero-cross on/off switching


by Dan Meeks @ edn.com:

This Design Idea is a solid state relay (SSR) which uses a triac to switch AC loads at high current. There are plenty of simple SSR circuits available, but this may be the simplest circuit that achieves turn-on and turn-off only when the AC line voltage is near zero.

Simple SSR has zero-cross on/off switching – [Link]

Sleep easy with this desk fan speed reducer


by Michael Whybray:

Most desk fans I have come across have three speeds: Full Speed, Almost Full Speed, and Off – useless if you want just a gentle air movement, and far too noisy if you are trying to get to sleep (in your bedroom of course, not at your work desk!). The squirrel cage induction motors they use have switches to two or more windings – and possibly a capacitor – to reduce the drive current. But unless the drive frequency is also reduced, the torque and speed stability are poor, so minimal speed reduction is usually available on these fans. Using a triac to provide phase control of the voltage works poorly for the same reason, with the speed very sensitive to the triac firing phase angle and fan load, and has a tendency to stall.

Sleep easy with this desk fan speed reducer – [Link]

Triac based lamp dimmer

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Triac based Indecent lamp dimmer is a simple circuit and it doesn’’t requires additional power supply, works directly with 110V AC or 230V AC. It is a low cost dimmer circuit for adjusting the light brightness of incandescent, Halogen Lamp, Light Bulb load up to 250 W.

Triac based lamp dimmer – [Link]

Renesas Computerized Electric Fan

Electric fans continue to sell at a steady pace, despite the widespread use of air conditioners. Recently, models have begun to appear on the market with features such as a variety of blade shapes, silent operation, and better air efficiency. Electric fans are also increasingly being used in concert with air conditioners to save electricity through better cooling efficiency.

Renesas offers microcontrollers such as the 4286 Group which is ideal for remote control function, the RL78 Family, the R8C Family, and the 78K Family which are ideal for system control, and TRIACs and photocouplers for peripheral components. We offer the best solutions for electric fan systems.

Renesas Computerized Electric Fan – [Link]

400VA AC Light Dimmer


This is a simple TRIAC AC load dimmer used to control the power of a resistive load such as incandescent lamp or heater element. The max load it can handle is 400VA. Such a circuit is often found on cheap commercial light dimmers and is proven to work reliable for the rated power.

400VA AC Light Dimmer – [Link]

LT3799 – create a LED driver with an active PFC

Isolated offline-flyback controller LT3799 enables to create a powerful LED driver with a minimum of external components, which is moreover compatible with common triac dimmers.

At the design of a new LED driver, we usually have to consider more factors like for example an output current stability, shortcut or open LED protection, efficiency, safety (isolated secondary circuit form the primary one), power factor correction, EMI, number of external components and other.

LT3799 meets all these requirements and offers another benefits, like for example a possibility to use a smaller transformer thanks to the use of critical conductivity mode, powerful external MOSFET driver, internal LDO regulator and also a very good output current regulation – typically +-5%, moreover with no opto-isolator. A big bonus is the active power factor correction, thanks to which it reaches typical values of 0,96 (at 230V AC), thus meeting the most stringent requirements in this field, as well as IEC 61000-3-2 class C about harmonic currents emission. When we look closer at the recommended application circuit, we´ll find out that behind a diode bridge we won´t find any (otherwise common) input electrolytic capacitor with value of tens or hundreds of uF. That´s why the input voltage of the controller and a of the power transformer “copies

Wireless TRIAC dimmer

Ivan Sergeev writes:

This project was used as a wireless light dimmer, but in principle can be used to dim resistive loads and wirelessly turn on/off loads. The current code includes a routine to dim a light bulb in a “heartbeat

Component tester

coremelt.net writes:

With this tool you can test various electronic components like diodes, LEDs, all kinds of transistors (PNP, NPN, several types of MOSFETs), capacitors, resistors as well as triacs and thyristors. It will show you several physical characteristics after the test was completed, like forward voltages, (gate) capacity and amplification factor. More over, it will show the polarity of the component and identifies the several pins of a package. A very nice and sophisticated project I host for Markus Frejek. I’ve done an additional layout for the device you can see on the left side. This project has found a lot of fans, including myself. The device is powered by an AVR ATmega 8 MCU.

Component tester – [Link]