Monthly Archives: March 2010

Arduino and relay, or driving 220V devices with Arduino 4

To move something in the real world, more volts and amperes are needed than Arduino can put out bu itself. Relay to the rescue. A relay is an electrically operated switch. Very nice description by Unfortunately, connecting a relay directly to Arduino is not possible or at least not feasible. Relays usually need more than 40mA at 5V to operate. And that is the maximum, Arduino can supply. So more electronic components are needed. At least three good stories, implementing almost the same schematics are,

Arduino and DS18B20 – 1-wire digital thermometer 6

Finally got this DS18B20 working. Actually three of them. And in two modes. Parasite power mode and main mode. A 4.7K ohm resistor is the key. Starting with the main mode, three wires are needed, as this sensor has three pins. Datasheet is here Connection is almost simple. Pin 1 to Arduino ground Pin 2 to Arduino digital input Pin 3 to Arduino 5V And a 4.7K resistor between pin 2 and pin 3 Works with three wires, as seen on the followind illustration.