In my previous post I talked about using a motor, a cam, and a switch to fire a solenoid. That just wasn’t going to work because it was too hard to get the right pace of the solenoid firing. The motor voltage changed its speed, and the cam idea was too difficult to adjust the cam shape and location.
In this post I’m showing how I switched to the Arduino Nano to control the firing rate of the solenoid. With the Arduino, it’s a 30-second program change to change the rate of the solenoid firing as opposed to the ridiculously difficult process with motor and cams.
The first video below shows the solenoid firing using the default settings in the sample ‘Blink’ program in the Arduino IDE.
The video below shows the solenoid firing after I modified the delay settings in the ‘Blink’ program.
Trying to find a way to mount things like motors, solenoids and switches is often a big challenge. Trying to find the right bracket, the right screws, and the right locations for those items in your experimental projects can be tough.
So I thought I’d show a few tips and tricks that I use.
First, my goal: I was trying to set up a little solenoid to bang against a miniature box to make a ‘chattering’ effect for a mini ‘monster in a box’ project, kind of like this Halloween monster in a box video (fast forward to about 1 min, 25 seconds to see the box chatter).
I started by experimenting with a little hobby motor. It wasn’t powerful enough to attach a cam straight away to rattle the box on its own so I had to find gears or levers, or something, to get some mechanical advantage.
The box in the video uses a cam attached to an electric drill, but I wanted something much smaller for my little project.
I started out using a cam to trigger a micro switch, which would energize a solenoid in rapid succession. (See my next post to see the solenoid fire.)
Instead of trying to find the right size and shape of a motor mount for my initial testing of things, I just used hot glue to secure some little blocks of wood to my test base (a 12″ square piece of press board). Then I put a little dab of hot glue on the motor and on the micro switch to secure them to the proper height of wood blocks.
Click on the photos to see larger versions.
Using blocks of wood is a fantastically simple way to make the right heights and locations. I was able to put away my box of sheet metal, tin snips, and other miscellaneous hard-to-use metal mounting hardware!
You can see my little blue cam that I also used hot glue for. I glued it to the motor shaft for a temporary attachment. Hitting the switch with the first cam — the brown pointy one you can see laying there — didn’t keep the switch activated long enough to fire the solenoid properly so I made the blue cam that kept the switch activated for about 5 times as long.The hot glue made it very easy to swap cams and re-glue.
The motor rotates at 300 to 600 RPM depending on the voltage applied (3 to 6 volts). That was way too fast with either cam, so I had to find another solution (see my post about using the Arduino instead of a motor). But the mounting techniques of wood blocks and hot glue have been a big headache-reliever for me over trying to find or fabricate metal mounts.
This video is old, but is a great training video on gears – car transmission gears in this case, but on a very basic and understandable way. It’s fun to watch just because it’s so old! But don’t let its age fool you — it’s got some great information!
A series circuit is one in which items are arranged in a chain, one following the other, so the current has only one path to take. The current is the same through each item.
Series circuits are used for several reasons:
1. To increase a voltage source.
The following is true of any standard battery, but let’s use the AA battery as an example. If you put one AA battery in a circuit, you will have a power source of 1.5 volts because that’s the voltage of a standard AA battery.
If you want 3 volts, you can place two AA batteries in series which gives you 1.5 V + 1.5V, which equals 3V.
Put three AA batteries in series and you will get 4.5 volts, etc.
More coming soon.
Also see: http://physics.bu.edu/py106/notes/Circuits.html
So you want to learn about electronics! Good for you! The sky is the limit when it comes to this field, but let’s start with a very simple circuit.
Lighting up a light emitting diode (LED).
The entire circuit is very simple — it consists of an LED, a power source (batteries), and a resistor to limit the current through the LED.
Light emitting diodes will emit light when a voltage is applied to them and current flows through them. Different colors and types of LEDs may require different voltages and currents, but a standard red LED requires 1.7 volts and .02 amps (20 milliamps, or 20 mA).
Here is a how to build your circuit if you’re a very beginner without many tools yet.
I have two AA batteries (1.5 volts each) that are connected in series to make about 3 volts. (Click here to learn about series connections.)
They are in a little battery holder with alligator clips that I soldered on to make the connections easier.connected to the LED and a current-limiting resistor.
I used an extra alligator clip to connect the resistor to the LED. You could use a paper clip, or just wind them together.
Here is what the circuit looks like in a schematic diagram:
Even this simple circuit needs a little forethought.