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Solenoid activation and circuit
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Solenoid activation and circuit

by novicerookster on Fri Jul 24, 2020 7:45 pm

I really am novice with this so thanks in advance for help on a very basic level.

My basic task is to run a solenoid on/off from a car battery.

I'm going to try using the "Small Push-Pull Solenoid - 12VDC PRODUCT ID: 412" but also buying the large to test as well as an alternative.

The Solenoid has this information note: To drive a solenoid you will need a power transistor and a diode, check this diagram for how to wire it to an Arduino or other microcontroller.
Image

For a simple on/off operation, I don't think I need a microcontroller / Arduino. Right?

And since no Arduino, I don't need a power transistor, right? The note implies I do need one, but maybe they are assuming use with an Arduino.

This is the circuit I drafted with products selected:
Image

Some more questions!
    Switch should go on the + side, correct?
    Is the diode necessary? Is it for over voltage protection? If not, what is the purpose?
    The 1st diagram calls for a 1N4004 diode. Adafruit doesn't list that product, but does have 1N4001, which seems interchangeable in this 12V operation, correct?
    Push Switch 2781 says it requires a 470ohm resistor for 12V operation. I'll have to figure out how to wire that.
    Toggle Switch 3218 has 3 leads. I think 1 config is for continuous illumination and another is for illumination when the switch is on. I'll have to figure out that wiring.

Once I get the basics figured out, I'm actually putting 3 (or more) in parallel:
Image

Thanks again in advance for the help and patience with the basics. I'd rather ask than start blowing stuff up and needlessly ruining new components!

I did read other posts before writing this up in hopes of finding my answers. I did take in the advice to allow for some initial travel of the solenoid before the force as it is weakest at the start of the stroke. I appreciate all answers and suggestions!

novicerookster
 
Posts: 2
Joined: Fri Jul 24, 2020 4:52 pm

Re: Solenoid activation and circuit

by adafruit_support_bill on Sat Jul 25, 2020 5:52 am

Your diagram is correct. For a switch operated circuit, the transistor is not necessary.

The diode is not absolutely necessary, but it is a good idea and will reduce arcing and improve the lifespan of your switch. Any of the 1n400x series will work as long is it is rated for at least as much current as the solenoid you are using.

The switch will work in either the high side or the low side. For higher voltage applications, high-side offers a bit more safety since there is no voltage exposed on the rest of the circuit when the switch is open.

adafruit_support_bill
 
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Joined: Sat Feb 07, 2009 10:11 am

Re: Solenoid activation and circuit

by novicerookster on Sun Jul 26, 2020 1:33 am

Thanks for the kind feedback Bill!

Follow-up question (I have been reading)...

This is in an auto, should I put a relay switch between the Car Battery and my first switch?

novicerookster
 
Posts: 2
Joined: Fri Jul 24, 2020 4:52 pm

Re: Solenoid activation and circuit

by adafruit_support_bill on Sun Jul 26, 2020 5:53 am

I'm not an expert on automotive wiring systems. I know that relays are often used to keep high-current wiring out of the passenger compartment. But I don't know what specific criteria apply in deciding when a relay should be used. Other than the added cost, it probably would not hurt to add one.

adafruit_support_bill
 
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Joined: Sat Feb 07, 2009 10:11 am

Please be positive and constructive with your questions and comments.