Hi, I am attempting to control 17 12v solenoids using my Raspberry Pi's GPIO pins. I have attempted to test this with one solenoid but the solenoid did not open. Here is a diagram I made of what my circuitry looks like:

 

hi jez.
Look at this Vgs plot for the FET, a 3v Gate voltage is too low.
Also what is the Gate diode for.?
The Solenoid requires a suppression diode.
E

 

Not surprising it doesn't work.

First the IRFZ44 requires a Vgs of 10V to fully turn on and shown here:

You need a logic-level type MOSFET whose ON resistance is specified at 3V or less.

Second the diode serves no purpose in the gate circuit. Furthermore it will not allow the MOSFET to turn on and off properly.
Instead, the diode should be connected across the solenoid (cathode to V+) to protect the MOSFET from the inductive transient voltage when the solenoid is turned off.

 

hi jez.
Look at this Vgs plot for the FET, a 3v Gate voltage is too low.
Also what is the Gate diode for.?
The Solenoid requires a suppression diode.
E

Not surprising it doesn't work.

First the IRFZ44 requires a Vgs of 10V to fully turn on and shown here:
View attachment 117387
You need a logic-level type MOSFET whose ON resistance is specified at 3V or less.

Second the diode serves no purpose in the gate circuit. Furthermore it will not allow the MOSFET to turn on and off properly.
Instead, the diode should be connected across the solenoid (cathode to V+) to protect the MOSFET from the inductive transient voltage when the solenoid is turned off.

Thanks for the replies. Do you know how I can search for the transistor and diode?

 

Do you know how I can search for the transistor and diode?

Look here for some info on and places to buy logic level MOSFETs.

The diode you have is fine for placing across the solenoid.

 

Look here for some info on and places to buy logic level MOSFETs.

The diode you have is fine for placing across the solenoid.

So I don't need a

suppression diode.

?

 

hi jez,
As posted, the diode shown in your post is suitable for suppressing the solenoid coil.

When choosing a N MOS FET do you want to use TAB body FET's ie: thru hole types rather than surface mount.?

BYW:
What is your location.?

 

hi jez,
As posted, the diode shown in your post is suitable for suppressing the solenoid coil.

When choosing a N MOS FET do you want to use TAB body FET's ie: thru hole types rather than surface mount.?

BYW:
What is your location.?

Sorry, I am quite new to transistors and solenoids... I don't know what you are asking.

 

Will the TIP120 work? It looks like it should.

 

The TIP120 looks OK for your application.

EDIT:
This is the proposed circuit. LTSpice
You will need a substantial power supply for 17 Solenoids at 12V 550mA rating.

 

Thank you ericgibbs and crutschow for your help.
So I have ordered all the parts I need, here is my updated diagram:

EDIT: Sorry ericgibbs, I didn't see the update to your post. Thanks for drawing up that circuit, does the ground go into the Raspberry Pi?

 

hi,
The diode is the wrong way around.
connect the 0v together, psu to Pi

 

hi,
The diode is the wrong way around.
connect the 0v together, psu to Pi

Yeah, I just realised that I had it the wrong way. So is this diagram correct? (I have already ordered the parts so I can't really change them)

 

Hello,

I now see that you have two threads for the same issue:
How do I work out the transistor needed?

One thread is enough.

Bertus