My Own Sprinkler Shield

Hi everyone,

i made a watering system for my garden. I used a classic 8 relay board to manage the 9v sprikler (bi-stable version).

My wish is to realize a Shield to shrink all the system in a single board.

I would like to know if exist an alternative "object" instead of my "SRD-05VDC-SL-C" because they are too big. What i need is a "switch" (a small solid state relay or an optocoupler) with 5v handler, able to support up to 24v (i am planning to buy a monostable solenoid)

thanks a lot


Are you switching DC? Is the switching just on-off (no polarity reversal)? If so, a logic level MOSFET, sized to handle the voltage and current, could do the job in place of the relay. The MOSFETs can be pretty small.

yes, i am switching DC, now 9v, in future 12v, perhaps 24v.

By now 4 switches are Just ON/OFF, but other 2 have to be NC-NO switching (diverter?)

Anyway, thanks for your reply, i will read some about MOSFET


Actually, i was thinking to use a simple photocoupler? is it possible?

I would connect the arduino pin to the led-side (so the 5V tension) and the 9v to the phototransistor side.

Is it possible? i will have the benefit to isolate the circuits.

Sure, i can combine the mosfet with the optocoupler...

Check the data sheet for the optocoupler for the maximum collector current of the phototransistor. It must be greater than the current that the solenoid (load) requires (plus some safety factor). Most that I have seen are around 50mA, probably not enough for a solenoid. If you use a MOSFET, do you really need the isolation? In any case, make sure that the solenoids have flyback diodes to absorb the inductive kick back when the inductive loads are deactivated.

Solenoid works with wather, outdoor and i guess the isolation is advisable.

Anywaly i can use the optocoupler to pilot the transistor if the mA are not enough..

i will let you know.


I found this component, may i use it? i'm not able to read datasheet very well...$file/CPC2907B.pdf

it seems i will have isolation and small size together


Are you sure you are switching 24vdc? Most of the sprinkler controllers I have played with used 24 volts AC to the control valves (granted my sample size is small).