I am very new to Arduino and electronics in general. I would like to make a project that uses an Arduino to control solenoid valves. I've been researching using relays to control the power going to the solenoid. I just wanted to post what I'm planning on buying and see if anyone can confirm this is going to work or where there are errors in my planning.
8 channel relay board (I'd like to scale up the project after initial testing, so 8 channels would be a good starting point)
My main questions right now would be, does my relay method seem fine? I've seen many solenoid projects online using relays but I've seen a lot of people on these forums suggesting transistors over relays. Does anyone have a suggestion for one to use in this project?
Is my choice of diode suitable?
Am I ok using the same power supply for both the relays and the valves.
I'd eventually like to control the on/off of the solenoids quite quickly at like 50ms open then 50ms closed (or even quicker 25ms say). Is my setup suitable for something like this?
Your relay method is fine for initial testing and slower switching. For fast switching, MOSFETs are a better choice. Check if the ratings of Schottky diode 1N5819 match your solenoid.
Thanks and good to know! I think I'll go for this relay method for initial testing and then look into MOSFETs in the future.
As for checking the diodes ratings, it says 100v maximum repetitive reverse voltage, 5A maximum average forward rectified current, and peak forward surge current 150A. These sound ok to me? The valve is 12v-300mA.
Thanks. So as far as I am aware, the relay needs 12v power, which will come from the power supply (also going to the solenoids), and then I can send 5v to control the switching of the relay from the Arduino. Does this sound correct?
Don't buy that relay board. I just noticed that the schematic they show does not match the board they show. It probably will not work with any arduino.
Lets discuss solenoids for a bit. To make a solenoid move really fast you use a voltage much above the rated voltage, but apply is for a very short time and then delay doing it again so the solenoid has a chance to cool. Usually a large value capacitor is used to store the extra current that is needed for the operation.
To make a solenoid return really fast, replace the original return spring with a much stronger spring. Much experimentation to arrive at the required parameters.
Thanks for noticing that. I wouldn't have clocked onto that. Based on JCA34F's suggestion below, do people think this MOSFET option would be a better choice?
The valve is 12v/300mA/3.6W, so seems like it will work fine? So with these MOSFETs I should be good to go, right? And again, I think the diodes match the solenoids specs too.
Interesting and way beyond me I reckon though I may be able to experiment with this when I get up and running. So I'd use a voltage way higher than rated, how much higher? And then drop it down to the rated voltage to keep it open? Is this method particularly problematic if I want to be repeatedly opening closing the valves in a loop of 50ms open 50ms closed for example.
This high speed part of the project is not essential, and definitely something to work on after I have a basic setup down, but is still good to be learning and getting advice, so thanks.
My experience with commercial equipment with 24 volt rotary solenoids that were powered with 120 volt DC to make them rotate very quickly with lots of torque, Then rest for perhaps one second. Usually one would rest for 5-10 seconds.
This is the first you have mentioned your are using solenoid valves. What fluid are they controlling that will both move and stop in 50ms? Must be a gas, not a liquid.
Yes, you could operate a solenoid valve with a high voltage/current and then hold at lower values. Using relays for such a system means you do not really have constant control of your required timing.