Pulse Solenoid Control

Hi all,

I'm messing around with some gardening electronics and testing a few ways to control water flow via controllable valves.

I've picked up a cheap ebay solenoid here: EBAY

Important specs are: 4.5V @ 500ma

Now I understand I need to pulse the solenoid to open it, question is:

Whats a simple circuit I can use to do this?

500ma is obviously more than an arduino output can handle, I got this one because of the low voltage requirements.

Cheers, Pazu

You can use a MOSFET to drive it from the supply. Make sure it is a logic level drive (works with 5v on the gate). You can put a series diode from 5V to drop the voltage to about 4.5V.


AOI514 from digikey, can sink that current thru the solenoid with direct gate control from an Arduino pin. http://www.digikey.com/product-search/en?vendor=0&keywords=aoi514 This board has 32 of them driven from 74HC595, which has way less drive capability than the '328P does. http://www.crossroadsfencing.com/BobuinoRev17/ |500x453

1) you need a switching device capable of 0.5A continuous - so a MOSFET or high performance bipolar switching transistor (such as STX724) 2) you need a diode across the coil to prevent inductive kick back - this is essential.

Now I understand I need to pulse the solenoid to open it, question is:

No, you just need to turn it on. The term "pulse" implies a single brief positive transistion or a series of on/off transistions. You solenoid simply needs go from the OFF state to the ON state and remain in the ON state until you are finished watering. That's not really a pulse. (unless you qualify it by specifying a pulse duration in minutes, not mS.