A new internet controlled lighting project called SplashLight is being developed. It has 4 relays to turn lights on and off, and 3 PWM outputs to drive RGB LEDs. The core of the project is a Cortex M3 uC with an Ethernet PHY/MAC from Texas Instruments.
The project includes iPhone, Android, and web applications to control the board over the web. It looks like the PCB and schematic files will be made available in the future, but the license is still unannounced. Might be ripe for a remake.
Network controlled relays & 3 channel PWM - [Link]
In this article I will tell you how to get shorter relay switching times and how to minimize relay current consumption. The same exact things apply to solenoids and solenoid valves.
You need to use a transistor because either relay you want to control needs a higher voltage than your microcontroller can provide, or relay’s current demand is too high. Although some microcontrollers can give enough current to switch a relay, but most of them is incapable of doing that.
And the diode in parallel with relay coil (or solenoid coil) is needed to suppress the flyback voltage that occurs when transistor is switching-off and magnetic field stored in coil collapses. That flyback voltage can reach hundreds of volts, which can completely destroy the driving transistor.
Using Relays (Tips & Tricks) - [Link]
DTMF-remote – Activate relays with your smartphone - [Link]
There are many types of relays that you might not be aware of. I found on schrackrelays.com a good explanation 0f the main types of relays. There are three main types:
Neutral relay, non-polarized relay
A neutral, monostable relay operates independently of the direction of the energizing direct current.
A polarized, monostable relay only operates in a specific direction of energization. It then adopts the operating state.
A polarized bistable relay adopts one switching position on energizing in a particular direction and the other switching position when the energizing is in the opposite direction. In a bistable relay with one winding, the opposite energizing is created by a voltage with an opposite polarity being applied to the same winding. In a bistable relay with two windings, the opposing energizing is created by a voltage with a reversed angular direction being applied to the second winding.
Remanent relay (remanence relay)
A remanent, bistable relay adopts a particular switching position at an energizing direct current in any direction and is held in this position by the remanence in the magnetic circuit, i.e. through the magnetization of parts of the magnetic circuit. The contacts shift to the other switching position on a small energizing current of limited amplitude in the opposite direction. This demagnetizes the magnetic circuit again.
Relays types: Neutral relay, Polarized relay, Remanent relay - [Link]
4 Channel Infrared (IR) Remote is a simple kit using the famous HT12A and HT12D encoder / decoder chips from Holtek
4 channel infrared remote relays - [Link]
I am happy to announce the release of our set of Free Electronics Stock photos. This is a collection of 286 usual electronics items that you may already being familiar with, but haven’t the time to take photos of them. You can use them on your blog, website or printed jobs for free. Great efforts have been made to achieve a professional look and being usefull to all of you. Electronic items photographed under DIY studio lighting and processed using software. They are categorized on the following categories:
- Chip – ICs
- Passive Components
- Switch – Relays
- Transformers – Inductors
Free electronics stock photos - [Link]