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Halogen bulb lamp dimmer circuit

Can someone provide me a (simple) schematic for a dimmer that would control 12 VAC about 80 watts. This would be used to control a lamp with halogen bulbs.

Anonymous asked on a comment few years back – Circuits FAQ

Here is a listing study them and choose, try out, learn and then build the one right for you.


This is a phase angle control of a Triac which is a evolution from an SCR. The 50 Hz or 60 Hz Sine wave of mains can be turned on at any point after the Zero Crossing

Triac based Lamp Dimmer power control

The Voltage ramps up in the sine wave which gives a near “Linear” slope which can be used to trigger the ON at a time delay after zero crossing when the voltage is zero. This is like a PWM but works on low frequency only. Some of the early SMPS(HV for TV and Mains Inverter) by Siemens were built around SCRs. Turning off a SCR is a difficult job for a designer, MOSFETS and IGBT are now used for PWM drive stages.

You can use it with a bulb to vary brightness of bulb, this is a live circuit it can give a shock, enclose in plastic box, the pot should have a plastic knob, use a fuse, you can also use it for temperature control of soldering irons.

The Source file in CadSoft EAGLE format is here del00004.zip

Digi – Wireless Device Networking

Device networking for business, develops reliable products and technologies to connect and securely manage local or remote electronic devices over the network or via the web.

Digi – Wireless Device Networking

External and embedded Wi-Fi products make it easy to add embedded 802.11a/b/g wireless LAN networking to any electronic device, or to connect serial devices over a Wi-Fi network.

Embedded Wireless and Wired Solutions
Digi - Wireless Device Networking

delabs Notes

Digii is one of the Pioneers of Device Networking or M2M as it may be called now. Some call the Systems applying these technologies as “Internet of Things – IoT” today (Home and Office Automation).

Derived for this Device Networking term, we have “Wireless Sensor(and Actuator) Networks – WSN” in Industrial Automation. In Robotics it is “Wireless Collaborative Robotics”.

If you see above closely, Sensor and Actuators with Intelligence is Robotics. So the dividing line disappears. The human is trying to make the machine more like him, both at work and play. Communications is important for that to happen.

Ananth – delabs Technologies

Updated Sept 2014

Let’s make robots – It is a Crowd of Bots

Let’s Make Robots is the ultimate community site where you can learn about robots, see what others have built, ask questions and get to know others in the community.

Let’s make robots – It is a Crowd of Bot

Navigate around via ultrasound. Detects fire and fight against it. CPU: Atmel ATmega328

It is named Mr. “Red” Adair, named after the well known firefighter Paul “Red” Adair. An Atmel ATmega328 controller acts as brain together with a Pololu LVDSMC as motor controller.

 Firefighting robot

Mr. “Red” Adair – Firefighting robot

For the blower motor (robbed from a defect hair dryer) a simple logic level N-FET (IRL540N) has been used. The chassis is from a cheap RC car illumninated with red, white and blue LEDs. As power supply 3 AA cells for the drive motors are used. A 9V battery block has been used for the blower motor and the 5V regulated controller supply