LM317 Questions

[Jbouss]

Great, Thank you!

I have learned a lot through all the feedback. I am going to order the transistor, and test it out:) Is the 2k2 resistor ok?

[ Specified attachment is not available ]

[edavid]

I think you are getting ahead of yourself, because you have not explained what these "switches" are.

If they are mechanical switches, there is no way they would be limited to 3.3V.

If they are electronic sensors, you have to provide power somehow.  Putting them in series is highly unlikely to work.

[Jbouss]

They are pressure switches activated by water flow. There is a dome-like structure inside that collapses when enough flow is present and that closes the switch. During their normal operation, they are connected to a system that uses a 3.3V signal to tell whether the switch is open or closed. This is how I know they can withstand 3.3V. In all likelihood, they could probably withstand 12V, but I do not know.

Out of the system, the switch works the same, when enough water flow is present the switch is closed, if water flow is lost, the switch opens. I want a light to indicate if an open event occurs, so my thinking was: If the switches are in series and closed with 3.3V running through them activating a relay(or transistor), as long as my circuit is wired correctly, if a switch opens, it will collapse my relay and turn on 12V to my light.

I'm sorry, I am new to electronics and am having a hard time understanding why putting the switches in series will not work? Thank you for your feedback.

[Circlotron]

If they are switches with mechanical contacts similar to what a relay has, i.e two pieces of metal that touch, then all should be good. If they have some kind of semiconductor switch e.g. Hall effect then that gets a bit more tricky. But from your description it sounds like it should be perfectly okay.

[edavid]

OK, that clarifies things a bit.

Since they are mechanical switches, you can put them in series.

Do you have a datasheet?

(BTW, are they pressure switches or flow switches?  Those are 2 separate things.)

[Jbouss]

Unfortunately no datasheet:(

I think they are flow switches. They use water pressure to activate, but, ~1.2PSI of air pressure will activate them on a bench.

[Circlotron]

How many wires come out of each switch? If there are only two then it sounds like they are a mechanical switch.

[edavid]

I think they are flow switches. They use water pressure to activate, but, ~1.2PSI of air pressure will activate them on a bench.

Why do you think they measure flow?

And if they are pressure switches, what is the point of using more than one of them?  Isn't the pressure the same everywhere in the system?

[Jbouss]

Hi Again, I got my transistor kit and tried out the below schematic, and there is something wrong

Currently, when I apply power, my LED tower just comes on.

[ Specified attachment is not available ]

[srb1954]

Hi Again, I got my transistor kit and tried out the below schematic, and there is something wrong

Currently, when I apply power, my LED tower just comes on.

(Attachment Link)

Should work. What transistor did you use? Have you triple checked the transistor leads are connected in the right order?

You can check that the transistor is working by applying a direct short between the base and emitter - the LEDs should go out.

N.B. your drawing title is confusing - this is a actually an NPN transistor, which is the correct type for this circuit configuration.