Question About Removing Transistor from Solenoid Circuit

Projects General Guidance
1

Hi Guys,

This is my first real Arduino project, and I have a question for you all. In all of the tutorials I'm reading about controlling a solenoid with an Arduino, it seems that people are using TIP120 transistors. What I have gathered is that this is done to solve the problem of the external power supply (usually batteries) not being able to provide sufficient current for the solenoid, which has a relatively high amp-draw.

In my case, however, have a pretty nice power supply that I'm going to be using to power my solenoid(s). The PS is a Mean Well SE-600-12, which can easily supply the amps that the solenoid needs.

My question to you all is how do I safely remove the TIP120 transistor from the following wiring/circuit diagram, in order to make everything work with my power supply?

Thanks a lot!

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(deleted)

3

Ah, I understand. So my setup should look exactly like the wiring diagram that I linked?

4

before you do that, order a new NANO to replace the one you burn up.

the transistor is there as a way to allow the power to go from the power supply to the motor, through the transistor, then to ground.

if you allow all that power to enter any pin on your arduino and expect to use that as the ground, it will fry your pin and probably the whole board.

5

LOL, at least I came here and asked before I removed the transistor from the circuit, right?

Another question for you all...

The Arduino Experimentation Kit that I got from Adafruit only includes the following transistors: P2N2222A. Will I be able to use those, or do I need to purchase a TIP120?

Thanks again guys.

6

Yes

BTW
It really helps if you make a link we can click on, use the link icon in the posting menu.

vs
Clickable link.

A 2N2222 can be used in lower power applications.
Test:
look up the data sheet and tell us what the max collector current is.

7

Didn't see any mention of the motor current rating in your post .

8

Ya I was just looking at the datasheets before I came here and read your reply. It looks like the P2N2222A has a continuous collector current of only 600 mA, as opposed to the TIP120 that is 5A. From the datasheets for my pinch valve, it looks like it only draws 0.4 amps, so I should be good?

9

If you use a 1N4001 flyback diode across the valve (cathode to +Vcc, anode to transistor collector)

10

raschemmel:
Didn't see any mention of the motor current rating in your post .

Yes

I think this is a solonoid.

The gain of the 2N2222 is 40 at 500ma.
.500/40=12.5ma
(5v-.7)/.0125=344 ohms use 270 for base resistor with the 2N2222 using your solenoid.

Edit
Make sure the transistor saturates.

.

11

raschemmel:
If you use a 1N4001 flyback diode across the valve (cathode to +Vcc, anode to transistor collector)

Yeah, I am going to mimic this wiring diagram.

1755×1575 327 KB

12

You can't run that valve off the arduino 5V. (at 400 mA , it is likely to cause the arduino to reset)

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Looks like s(he) is running it off Vin, which is also not recommended.

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raschemmel:
You can't run that valve off the arduino 5V.

Even if I power it with an external 12V power supply?

LarryD:
I think this is a solonoid.

It is a Clippard NPV3-1C-05-12.

15

Even if I power it with an external 12V power supply?

If you did that you wouldn't be running it off the arduino 5V any more would you ?

Looks like s(he) is running it off Vin, which is also not recommended.

Your right. I didn't read the pin label because the Fritzing didn't show a cable plugged into the external dc barreljack. (I should have expected that, actually)

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raschemmel:
If you did that you wouldn't be running it off the arduino 5V any more would you ?

Oh, I see. I posted the wrong wiring diagram pic. Sorry, hah!

I guess this is closer to what I will be mimicking.

17

I guess this is closer to what I will be mimicking.

I do not like the word mimicking.
Better say 'using'. :wink:

.

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LarryD:
I do not like the word mimicking.
Better say 'using'. :wink:

Hah, well I said mimicking because mine is not going to be exactly the same. The 9V batteries will be replaced with my power supply and the TIP120 will be replaced with the P2N2222A. Do you guys see any problem with my plan?

Thanks again for the quick replies, guys! And thanks for going easy on my noob-ass.

19

Well, the proof is in 'your' pudding.
When the transistor is turned on, make sure the collector to emitter is 1V or less (saturated).

Edit
And the transistor is not hot.

.

20

LarryD:
Well, the proof is in 'your' pudding.
When the transistor is turned on, make sure the collector to emitter is 1V or less (saturated).

I am 98% sure that I can figure out how to do that. I will try my best. Thanks!

Oh, and is there anything I have to change in the circuit since this valve is the "normally-closed" type, as opposed to "normally-open?"