Now that we’re just about finished with water drop photography, my dad and I are starting to think about what our next project should be. We’ve thought about it a little, and here’s what we’ve come up with: time-lapse photography.
Time-lapse photography is when you take pictures over a period of time, then put them together and make a video. There are programs you can use to put pictures together and make them into a time-lapse video. This can be really cool because every second of video could end up being two hours in real life.
My dad and I aren’t certain what we’re going to take pictures of, but some of our ideas include planting a flower seed and watching it grow, getting an ant farm and watching the ants dig tunnels, and taking pictures of a sunset. When we figure out exactly what we want to, I’ll write about what our plans are.
What is an electromagnet and how does it work? The answer to this question will help you better understand what happens in a relay and why it works. My dad and I did an experiment to find the answer.
The picture above shows an iron core nail wrapped in wire. When the ends of the wire are put onto opposite sides of a D cell battery, the nail becomes magnetic! This is an example of an electromagnet. Here’s a quote from http://www.electronicsteacher.com/succeed-in-physical-science/magnetism/electromagnetism.php that explains how electromagnets work.
“When electricity passed through a wire, a magnetic field is created around the wire. Looping the wire increases the magnetic field. Adding an iron core greatly increases the effect and creates an electromagnet. You can create an electromagnet without and iron core. That is usually called a solenoid.”
Basically what the quote is saying is the wire creates a magnetic field around the iron core nail, causing the nail to become magnetic. Did you see that the quote mentions a solenoid? The valve we used in our water drop photography was called a solenoid valve because it has an electromagnet inside of it.
Inside a relay there is a coil wrapped around an iron core and a switch. When power is given to the coil, the iron core becomes magnetic and the switch snaps shut. The switch closes because it is drawn to the electromagnet. When the switch is closed, the circuit is complete and electricity can flow. When power stops coming through the coil, the iron core is no longer magnetic and the switch opens, making it impossible for electricity to flow through the circuit.
If you want to try the experiment my dad and I did, all you need is an iron core nail, a wire, a D cell battery, and something metal that will stick to the electromagnet. Good luck if you decide to give it a try!
All of our pieces are put together and our programing works great! Today we took a bunch of water drop photos. The photo above is one of many photos we took. Here are some other ones we took.
Now, I bet you’re wondering how we took these photos. Here are some pictures of the rig we made to take these amazing photos.
The first picture shows a bottle connected to the solenoid valve. The bottle is filled with water, and when the solenoid valve is opened, the water in the bottle goes through the solenoid valve and exits the solenoid valve. This process is similar to what a sink does. The next picture shows a camera and a bowl of water. Remember the infrared shutter release I was talking about in earlier posts? It’s connected to the Raspberry Pi, and it tells the camera exactly when to take a picture of the water drops. The bowl of water is what the first water drop bounces off of. If you look back at the water drop photos, you can see the bowl in the bottom of the picture. The last picture shows the whole rig hooked up and ready to go. See the little rooster-shaped thing holding the pipe onto the table? The infrared shutter release is taped to the bottom of it.
This is really cool. I took us a long time to get the programming just right so the drops and the camera did everything when they were supposed to. I hope you enjoyed looking at the cool pictures we took. I’ll put up photos of things other than just water soon.
We finally got the camera and solenoid valve circuits working! Above is a picture of the circuit we built and tested. I’ve already told you in a previous post how our old camera control circuit worked, and this one is pretty much the same. As for the solenoid valve circuit, here’s how it works:
A brown wire runs from the Raspberry Cobbler to the red wire on the other breadboard. This red wire is connected to a one kilo-ohm resistor. The resistor is connected to the base of an NPN transistor. The emitter of the NPN transistor is connected to ground. The collector of the NPN transistor is connected to one side of the coil in the black relay. The other side of the coil is connected to a twelve volt power source. The switch in the black relay is connected to the solenoid. It switches power to the solenoid. When power is switched to the solenoid, it will release water.
We solved the problem we were having with our transistor. There was too much current flowing through the transistor, so we used a relay to handle the high current of the solenoid.
We wrote the program to control the infrared shutter release and the solenoid valve in Python. Once all our circuits were hooked up, we ran the program, and it was successful!
My dad and I were testing a circuit we’d made to control the solenoid valve(the thing we’re going to use to drop water), but we couldn’t get it to work. At first, we couldn’t figure out what was causing the circuit to fail, but we eventually smelled something burning. We figured out that we had burnt the diode, but this diode was a safety feature, and the circuit should’ve worked without the diode. My dad was thinking about this and he finally came up with the answer to our question.
My dad looked up the amount of current our NPN transistor could have flow through it. He said it could have 200 milliamps flow through it. Now, you have to understand, one amp is a lot of current. In our circuit, we had 1 amp, 1000 milliamps, flowing through our transistor. All that current burnt our transistor. Without the transistor, our circuit couldn’t work.
We’re still not entirely sure how we’re going to fix this problem, but when we do, I’ll write about it.
To activate the camera in our water drop photography, my dad and I are going to use an infrared shutter release that will tell the camera to take a picture. We wired the infrared shutter release up to the Raspberry Pi, and when we run the program we made in Python, the camera takes a picture! The picture above is part of the circuit we made to control the camera. We used the program we made to take the picture above.
The circuit we made consists of a few different parts. The T-shaped blue thing in the picture above is called the Raspberry Cobbler. It connects the circuit to the Raspberry Pi. The yellow wire is connecting the output pin of the Raspberry Pi to a resistor. The resistor causes less current to flow. Without a resistor, too much current would flow causing the circuit to blow. The resistor is connected to the “base” of an NPN transistor, the black thing with three legs. The emitter of the transistor is connected to ground by the purple wire and the black wire, and the dark green wire connects it to the other part of the circuit(in the picture below).
The dark green wire towards the top of the picture below is the same wire you saw in the picture at the top of the page. The two black wires you can see are connected to the infrared shutter release. Inside the reed relay(the blue thing) is a switch. When I run the program, the circuit gets power and the switch closes. This powers the infrared shutter release and tells the camera to take a picture. The orange, brown, and yellow wires connect the parts together so the electricity can flow. The little black cylinder is called a diode, and it’s there for safety reasons. Without the diode, the reed relay could damage the circuit.
I’m so happy we finally got this working! Check back soon for more updates on our progress!
I recently got a small computer called a Raspberry Pi(shown in the picture above). The Raspberry Pi is around $25 and was made specifically to teach kids more about computers. My dad and I set up the Raspberry Pi. We want to use it to do water drop photography. We’re going to make a program that, when run by the Raspberry Pi, will drop one drop of water into a bucket of water, wait a moment, then drop another drop of water into the bucket. The first drop will bounce off the water in the bucket and hit the second drop of water. When the two drops hit, they will form a cool umbrella-like shape. At this time, a camera will be triggered and it will take a picture of the beautiful shape.
I’ll post updates whenever we make progress. Check back every few days to see how we’re doing!
Here’s a link to the website we got the idea to do water drop photography from: http://davidhunt.ie/?p=2770