Tag Archives: Dimmer

Programmable LED dimmer

A Programmable LED dimmer from Soldernerd:

Around one and a half years ago I’ve designed and built various LED dimmers for both white and RGB LEDs. Then late last year someone approached me asking if I could make an RGB dimmer for him, too. But my designs were really tailored to their specific applications and built with home-made, i.e. milled PCBs which are time-consuming to make. So I decided to make a more universal version based on a proper, etched board which could be built in a small series and used for all kind of applications, both white and RGB. The result is this versatile, programmable 4-channel dimmer.

Programmable LED dimmer – [Link]

Multichannel Wireless Light Dimmer

abhishek123 @ instructables.com writes:

This project aims to

Control the intensity of the dimmable lighting appliances via a trailing edge dimmer.

Provide the user , ability to control lightsindependently and wirelessly over the Wi-Fi network and the Internet!

Multichannel Wireless Light Dimmer – [Link]

230V AC dimmer, mains isolated, using PIC12F629

dimmer

This is a very simple mains isolated dimmer with a triac output (phase control). It uses timer0 to do the timing.

There is no user interface, the value of the triac ignition delay after a zero crossing is defined by setting the reload value of timer0 (Tmr0) in the software directly. This value can e.g. be derived from a user interface or sensor or some algorithm. In the example it is stepped trough a number of values sequentially.

230V AC dimmer, mains isolated, using PIC12F629 – [Link]

12V NE555 PWM Controller

FBL1YSEISCAQG0A.MEDIUM

baelza.bubba @ instructables.com build his own PWM controller which is able to operate as a 12V Motor Speed Controller, LED Dimmer, Heat controller, voltage controller for an electrolytic etcher etc.

 

I did some hunting around on the interweb and found a pretty good starting point in Circuits Today, but then, I needed to make some modification and tweaking of the circuit. I wanted to add in a toggle switch, a DC power socket and a 2 pin screw terminal into the design to make it easier to make and use.

12V NE555 PWM Controller – [Link]

AC PWM dimmer for Arduino

FXN117QIMGLKAS4.MEDIUM

diy_bloke @ instructables.com has designed an AC PWM dimmer for Arduino:

Over 3 years ago, I published a simpel TRIAC AC dimmer for the arduino. That proved to be a very popular design. Yet in spite of the simplicity of the circuit the software needed was a bit complicated as it needed to keep track of the zero crossing of the AC signal, then keep track of the time and then finally open the TRIAC. So to avoid letting the arduino just wait for most of the time, an interrupt and a timer were necessary.

AC PWM dimmer for Arduino – [Link]

RELATED POSTS

Arduino controlled Triac light dimmer

F3QO7VAH8W1VGLR.MEDIUM

diy_bloke @ instructables.com has build an arduino controlled triac light dimmer and describes the circuit and software used to achieve that.

It becomes a bit more tricky if one wants to dim a mains AC lamp with an arduino: just limiting the current through e.g. a transistor is not really possible due to the large power the transistor then will need to dissipate, resulting in much heat and it is also not efficient from an energy use point of view.

Arduino controlled Triac light dimmer – [Link]

PWM dimmer for RGB LED

20160128_Projekte_061-600x399

Lukas Fassler has designed and built a PWM dimmer for RGB LED:

In my last post I’ve described the design and construction of my LED dimmer project. This project here is similar but a bit more involved. It controls RGB LEDs so it can not only change the brightness but also the color of the light. Instead of a simple pot it used a pair of rotary encoders with push buttons. One controls the brightness, pushing its button turns the light on or off. The other changes the color, pushing its button toggles between color and white.

PWM dimmer for RGB LED – [Link]

RELATED POSTS

PWM dimmer for LED lighting

20160119_projekte_046

Lukas Fassler has published a new project, a DIY PWM dimmer for LED lighting. The dimmer can handle 100W@12V and is controlled by a single potentiometer.

I have recently moved to a new apartment and was looking for a PWM dimmer to control some 12V LED strips. I thought that should be easy enough nowadays but it proved more difficult than I thought. All I found either didn’t meet my requirements, were uggly or expensive. So I decided to build my own, tailor-made to my needs.

PWM dimmer for LED lighting – [Link]

RELATED POSTS

PWM Halogen Lamp Dimmer

F060

High Current PWM Halogen Dimmer controller project is designed around SG3525 IC and High current MOSFET. Project can handle lamp up to 5 Amps (10Amps Possible with big heat sink) and supply 12-24V DC .Ideal for Halogen Dichroic Lamp or Halogen Lamp.

Specifications 

  • Supply input 15 to 24 VDC
  • Load-Lamp 12 to 24 VDC @ 5 Amps (10amps possible with big heat sink on Mosfet)
  • Onboard preset for frequency adjust
  • Frequency adjustable 4 KHz to 30 KHz
  • PWM Duty cycle 0 to 100% (+/- 5%)
  • Potentiometer for dimming adjust
  • Soft Start facility
  • Clamp diode for protection
  • Power-On LED indicator
  • Compact design and high quality
  • Lamp and supply connection via screw terminal connector
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 56 mm x 42 mm

PWM Halogen Lamp Dimmer – [Link]

Basic Types of Thyristors and Applications

In this article we will discuss about the various types of thyristors. Thyristors are 2 pin to 4 pin semiconductor devices that act like switches. For example a 2 pin thyristor only conducts when the voltage across its pins exceeds the breakdown voltage of the device. For a 3 pin thyristor the current path is controlled by the third pin and when a voltage or current is applied to this pin the thyristor conducts. In contrast to trasistors, thyristors only work on ON and OFF states and there is no partial conduction state between these two states. Basic types of thyristors are: SCR, SCS, Triac, Four-layer diode and Diac.

Silicon Controlled Rectifier (SCR)

SCR

Silicon controlled rectifier is normally in OFF state but when a small current enters its gate G it goes to ON state. If the gate current is removed the SCR remains in ON state and to turn it of the anode to cathode current must be removed or the anode must be set to a negative voltage in relation to cathode. The current only flows in one direction from anode to cathode. SCRs are used in switching circuits, phase control circuits, inverting circuits etc.

Silicon Controlled Switch (SCS)

SCS

Working of SCS is similar to SCR but also it can be turned off by applying a positive pulse on the anode gate. The SCS can also turned ON by applying a negative pulse on anode gate. The current flows only from anode to cathode. SCS are used in counters, lamp drivers, logic circuits etc.

Triac

triac

Triac is similar to SCR but it conducts in both directions, means that it can switch AC and DC currents. The triac remain in ON state only when there is current in gate G and switched OFF when this current is removed. Current is flowing in both directions between MT1 and MT2.

Four layer diode

four_layer_diode

Four layer diode has 2 pins and works like a voltage-sensitive switch. When the voltage between the two pins exceeds the breakdown voltage it turns ON, otherwise it’s OFF. Current flows from anode to cathode.

Diac

diac

Diac is similar to four-layer diode but it can conduct in both directions meaning it can contact both AC and DC currents.

Basic SCR Applications

Basic Latching Circuit

latching_circuit

In this circuit a SCR is used to form a basic latching circuit. S1 is a normally open switch and S2 is a normally close switch. When S1 is pushed momentary a small current goes into the gate of SCR and turning it ON, thus powering the load. To turn it off we have to push the S2 push-button so the current through SCR stops. Resistor RG is used to set the gate voltage of SCR.

Power Control Circuit

scr_power_control

In this circuit a SCR is used to modify a sinusoidal signal so that the load receives less power than of what would receive if source voltage was applied directly. The sinusoidal signal is applied to the gate of SCR via R1. When the voltage on the gate exceeds the trigger voltage of SCR, it goes to ON state and Vs is applied to the load. During the negative portion of the sine wave the SCR is in OFF state. Increasing R1 has the effect of decreasing the voltage applied to the gate of SCR and thus creating a lag in the conduction time. In this was the load is receiving power for less time and thus the average power to load is lower.

DC motor Speed Controller

dc_motor_control

This is a variable speed DC motor controller using a UJT, a SCR and few passive components. UJT along with resistors and capacitor form an oscillator that supplies AC voltage to the gate of SCR. When the gate voltage exceeds the triggering voltage of SCR, the SCR turns ON and motor is running. By adjusting the potentiometer the output frequency of oscillator is changing and thus the times the SCR triggered is changing, which in turn changes the speed of the motor. In this way the motor is receiving a series of pulses that average over time and the speed is adjusted.

Basic TRIAC Applications

AC Light Dimmer

ac_light_dimmer

This is an AC light dimmer formed by a diac, a triac and some passive components. The capacitor is charging through the two resistors and when the voltage on one end of the diac exceeds the breakdown voltage it goes ON and sends a current to the gate of triac putting the triac to ON state and thus powering the lamp. After the capacitor is discharged to a voltage below the breakdown voltage of diac, the diac, triac and lamp turn off. Then the capacitor is charged again and so on. So the lamp is only powered for a fraction of time during the full sinewave. This happens very quickly and the lamp seems dimmed. Brightness is adjusted using the potentiometer.