Opensprinkler bee how to#

Because you also need a state where no voltage is applied on the solenoid, that’s three states in total and hence two microcontroller pins are required to produce three states. By closing the pair of switches in each diagonal direction, you can apply voltage in either positive or negative polarity. The H-Bridge is made of four MOSFET switches.

Opensprinkler bee how to#

How to apply a voltage in both polarities? This is by using another neat circuitry called ‘ H-Bridge‘. This way you can generate a high voltage from a low-voltage source such as AA batteries. The Wikipedia has plenty of information about how it works, but the basic principle is to use a MOSFET switch, an inductor, a diode, and a PWM signal to build up the charge into a capacitor. How to generate such a high voltage from Arduino’s 5V or 3.3V pin? It’s by using a neat circuitry called ‘ boost converter‘. So you can’t apply the voltage continuously (or it will smoke the coil or the power supply!) In addition, it’s better to first build up the voltage into a capacitor, and then dump the charge to the valve from the capaictor. Because the coil resistance is so low, the instantaneous current is very high, up to a few amps. The important thing to keep in mind is that the voltage is applied as a pulse - usually 25 to 100 milliseconds. To close the valve, just reverse the voltage polarity. The specific voltage depends on the valve specification, but it typically varies between 9V to 22V. To open the valve, you apply a momentary positive voltage on the coil. How to open or close the latching solenoid valve? Electrically, latching solenoid valves have quite low coil resistance (a few ohms). For valves with special plugs, you can cut and strip two pieces of wire (20 to 24 AWG): insert one end of the wire to the plug, and the other end to the screw terminal block. Note the special plugs and/or different wire colors.įor valves that come with stripped wires, simply attach them to the screw terminal blocks on OSBee shield. Here are some examples of latching solenoid valves.

24V AC valves usually come with just two wires colored in the same way (because AC voltage has no polarity).

Latching solenoid valves usually come with a special plug, and the two wires are usually colored differently because the solenoid has polarity. Is there any easy way to tell latching solenoid valves from 24V AC valves? Yes. The OSBee Arduino library has one example of using the Arduino Ethernet shield with OSBee shield to create a web interface for sprinkler control. While OSBee shield itself does not have built-in wireless modules, you can stack it with other Arduino shields, such as RF, WiFi, Ethernet shields, to provide web connectivity. The other OpenSprinkler products, such as OpenSprinkler 2.1s, DIY 2.1u, OSPi 1.4, OSBo 1.0, are all designed for 24V AC sprinkler valves, which operate on 24V AC and require a power adapter / transformer. So it’s very efficient and suitable for battery-operated controllers. These valves internally use a latching solenoid, which only draws power when you open or close the valve, and does not draw power if it remains in the same state. How is the OpenSprinkler Bee (OSBee) different from the other OpenSprinkler products? The main difference is that OSBee is designed to work with battery-operated sprinkler valves. So to use the shield, you will need to provide an existing Arduino board. So what is this Arduino shield version, and how is this different from other OpenSprinkler prodcuts that we carry? Well, an Arduino shield is a circuit board that you plug into an existing Arduino - it does not have a microcontroller chip itself, but contains additional circuitry that extends the basic functionality of an Arduino. While that’s still in the development stage, today I am glad to announce that an Arduino shield version of OpenSprinkler Bee is completed and immediately available for purchase at the Rayshobby Shop. Two months ago, I wrote a blog post about the preview of OpenSprinkler Bee, which is an open-source arduino-based controller for battery-operated sprinkler valves. Update: check out our new standalone OpenSprinkler Bee (OSBee) 2.0 with built-in WiFi and OLED display.