Pulse Solenoid Control

Using Arduino General Electronics
1

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

2

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.

Weedpharma

3

AOI514 from digikey, can sink that current thru the solenoid with direct gate control from an Arduino pin.

This board has 32 of them driven from 74HC595, which has way less drive capability than the '328P does.
http://www.crossroadsfencing.com/BobuinoRev17/

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4
  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.
5

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.