What if there's no power - how do I control my pneumatic circuit?
If the lights go out and you need to see, or you need to control a pneumatic circuit without power, then your eyes are your light. This experiment demonstrates how to use the power of your eyes with some household materials and a bright flashlight.
With this method it is possible to turn on an LED which controls a pneumatic circuit by activating an MR-8 relay through an IR remote.
Alternatively, if you want something more versatile than just turning on an LED for basic tasks like tuning in radio stations, then these two methods combined can be used to control other tasks as well.
Here is a quick video of the IR controlled pneumatic circuit:
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Disclaimer: I do not recommend or endorse any of the materials mentioned in this post, I am just sharing my experience with you. You should purchase and use these materials at your own risk. Always read and follow all safety instructions that come with the products. None of these projects are intended for use by children unless otherwise noted. Be safe!
That's my word for the day. See you tomorrow.
"Seek first to understand, then to be understood." ― John W. Gardner With the recent news of an electrical fire at a local college and the tragic loss of life in that accident, I thought it would be interesting to share some tips with you on how to safely connect up your pneumatic circuit.
Connecting Up Your Pneumatic Circuit You may not think it's very important, but I can assure you it can save your life if there's an electrical fire or if the power goes out (which is most likely going to happen eventually).
Fire Prevention
This is the most important tip. The purpose of all this is to prevent electrical fires from starting in the first place. You have a few options when it comes to getting power to your circuit: batteries, AC wall adapter, and/or DC wall adapter. I recommend using batteries if you are not using an IR remote (for extra safety) and only running a small circuit. If you are running a large circuit or want more control, use an AC or DC wall adapter instead. It is very important that you either use an isolation transformer or an isolation relay when connecting up your circuit to avoid fire hazards. An isolation relay would be the best choice. It basically does the same thing as an isolation transformer with the added benefit of being able to completely isolate your pneumatic circuit from your power source (like a wall adapter) so that you don't need to worry about changing any fuses and it can't blow a fuse. To use an isolation relay with a wall adapter, simply plug in your wall adapter into the isolated outlet on the relay and plug your pneumatic circuit into the regular AC outlet on the relay.
With this set up you can get up to 15 amps at 120 vac of power, which should be enough for most hobbyist-level pneumatic circuits.
To add even more safety you can also use a timer to shut off your pneumatic circuit after a certain amount of time. The use of timers is not required, but I highly recommend it if you're charging your circuit for longer than 60 seconds. You can find the breakout board for the SparkFun M04936 IR relays here : [GitHub][Sparkfun]
WARNING: Be careful when using timers. It is possible that the relay can turn off your circuit before it has a chance to fully charge if you use a large resistance.
NOTE: The SparkFun M04936 should be plugged into an AC outlet, not into the wall adapter. Safety First! It's important to use fuses for your pneumatic circuit as well, here is why: Relays are useless without fuses. If there's an electrical fire, fuses are going to protect the wires and keep everything from burning up. Fuses also protect you from electrical shocks and other things that could hurt you and others around you. For example, lets say the power goes out and your fan turns on by itself (using an IR remote). Without a fuse, you are going to run the risk of an electrical fire. If you have a fuse, then everything will be fine. Fuses also protect your pneumatic circuit from over current conditions. This could happen if you try to turn on too many things at once, have the wrong sized wire, or if your load is too high for the size of your circuit (for example). A fuse will protect your circuit and make sure that it doesn't fry by blowing its fuse before anything else is damaged. The use of fuses isn't very common in hobbyist-level pneumatics because it isn't cost effective and there aren't very many commercially available products that can easily integrate with Arduino boards since they require AC power. To make your own fuses you need to buy a fuse holder and some fuses. The fuse holder is used to hold the fuses in place on your circuit and the fuses are used to protect them from over current conditions. A good fuse holder can be purchased here: [ Amazon ][ SparkFun ][ Jameco ][ DigiKey ] [ Home Depot ] They usually come in strips of 10 or more. Here is an example of a typical pneumatic circuit using an IR remote with a wall adapter for power:
The two things that you need to look out for are using proper wire sizes and sizing your capacitor properly.
Using the right wire size is crucial. If you use too small of a wire size, you risk having your circuit overheat and catch on fire. If you use large wire sizes, it's not as much of a concern for fire hazards (but it will still cause problems), but it will certainly increase your cost to build your circuit because it'll require more expensive components. You can always use smaller wire sizes and/or fuses to protect yourself if the wrong sized wires are used, but there is no protection from frying your circuit if you try to use large wire if it's not meant for large loads. Never use solid core wires either, they are bad for a variety of reasons .
Conclusion
I'm not going to go into detail about how to size your capacitor here because I wrote an entire article about it before: [ Sizing Your Capacitor ]. In short, capacitors are used for storing up energy and pulsing it out at a constant rate over time. The main thing to remember is that capacitors are rated in Farads and the higher the capacitance, the longer you can run your fan for in between pulsing it. If you use a very large fan like a 60x60x20 mm blower, it will require a larger capacitor than if you use a smaller fan like an 8x8x8 mm axial fan.