First post!
Hello, I have been playing with my Uno for maybe a year now and have a real world application that I will be using it for (until I get better with microprocessors and can reduce the physical size of the project)
I have seen people powering solenoids with a separate power supply and I could do so as they do, but I am wondering if I can power the Arduino safely with the same 12V power supply as the 12V solenoid.
If I could do so I would get to save a 5V power supply and reduce the physical footprint of the whole design.
I have been thinking about this very hard and I am a little burnt out and looking for some external advice since nobody I know has any idea about how any of these things work.
My worry is that I would potentially short the I/O pin to ground through the transistor(will be switching to mofset) my idea for a potential solution would just be a diode to keep the current going in the correct direction.
I burnt up one Arduino from what I think was not using a snubber/flyback diode across the solenoid connection.
Thank you in advance if you have anything to add or warn me from doing! I hope I can one day be smart enough on these things to help others!
OP's diagram:
It's nominally okay. What value is the base resistor?
aarg:
OP's diagram:
It's nominally okay. What value is the base resistor?
Thanks for the reply!
I would plan on using a 1000 Ohm resistor at the base to limit the current to 12mA, if my knowledge of ohms law is correct!
I would hate to blow another board since we have growing plants that will need transplanted soon. I really hope I can save my parents the money they would spend on the wall outlet timer, and have a working project that I can show to others.
Here's a more standard way of drawing your diagram.
The transistor could be a simple NPN, or it could be TIP120.
Note the Gnd from the12V driving the solenoid coil (or a relay coil, or a motor coil) must be connected to the Arduino Gnd. Any Arduino Gnd.
CrossRoads:
Here's a more standard way of drawing your diagram.
The transistor could be a simple NPN, or it could be TIP120.
Note the Gnd from the12V driving the solenoid coil (or a relay coil, or a motor coil) must be connected to the Arduino Gnd. Any Arduino Gnd.
Hi Crossroads!
So in the configuration in this circuit you show, is the Arduino being powered through the grounds? or is that the information that I moved over to the side and put in yellow. Everything I put in yellow is where I am having trouble understanding this circuit.
Also, I apologize for not knowing how to get the image displayed in the post.
How to add images into your post.
What is it you don't understand?
I am going to redraw the 2 circuits the proper way to demonstrate my question. I do have it hooked up and running exactly how it should at the moment. I’ll include pictures of the whole unit as well!
wvmarle:
What is it you don't understand?
My assessment is that it is the difference between current and voltage.
My question has nothing to do with current or voltage. I took physics and have a firm grasp on Newtons laws, Wave Functions, Coulombs law, and Kirchoff's Laws. I have these laws all wrote down multiple times and even have copies of the printed equation sheets handy for when I am studying these topics. I don't know why aargs assessment would be that I don't understand current and voltage when I never said anything regarding.
The circuit on the left is my current set up. Programmed to the time I need and working exactly as intended without fault for hours now.
The circuit on the right would save me an AC to DC converter power supply and eliminate extra soldering required when we put in more of these units.
My question is Is the circuit on the right safe to use, and if not why? I don't see anyone doing it this way so I was going to refrain from doing so until my ruggeduino arrives and I could try it out.
Ive also included pictures of the version 1 hydroponic system. I plan to buy some attiny85's to play with and hopefully get this working with those and get my Arduino back!
Picture of the system. They seem to be popular on YouTube. I didn't build any of that stuff, just helped save some money on a programmable timer with the Arduino.
Yes, you could use the same 12V supply for the barrel Jack and the solenoid coil. 5V regulator may get warm, depending on how many transistors you drive at one time.
