Hello, I'm new to this forum and to arduino programming and hardware so please excuse me if I am unaware of a few customs and courtesies. I'm trying to make an arduino-controlled miniature potato gun, where I have a high voltage source with stripped wires create a spark on command to ignite hairspray contained in a plastic bottle to shoot a q-tip.
I have access to diodes and transistors, and I'm trying to wire it so that when I press a button, for example, it causes the transistor to close the switch and allow the electricity from the high voltage source to flow and create a spark. How would I wire this up?
I want this to be adaptable so that I can use various sensor inputs be the trigger that set off the spark. Getting it started by figuring out how to make a button fire it is just proof of concept.
I want to use an arduino for this because I eventually don't want to have to fire it by hand, I'm thinking of using a pixycam that can detect an object, like a brightly colored piece of construction paper, and fire at it.
The hairspray might singe the q-tip, but not badly. I'd rather not create a pneumatic system, and figure out how to get an arduino to release the compressed air on command.
Not necessarily, it would be no more dangerous than getting a static shock from a door knob on a cold day or dragging your feet (with socks) on a carpet...
Now if you went with say a neon sign transformer (don't btw), then yeah, that may do some damage.
Put 2 wires in contact with 5V flowing through and pull them apart. There will be a tiny spark. With 12V you will see the spark.
Run current through fine steel wool, it will burn.
Bend a weak spot in a wire and run current through that, the thinner the wire the faster it gets red hot at lower voltage.
I've used a 9 volt battery and two wires and by connecting the wires to the positive and negative ends of the battery and touching them together, I've managed to get a tiny spark. What I want to do is to fix these two wires in place and set the spark off on command using an arduino to open and close the switch, the switch being a transistor. I'm just not sure how to wire the transistor and code it to get this done.
If you can find an old disposable camera with a Zenon strobe flash, those use a high voltage.
Or, you might look for a circuit for a "shock toy". (We don't discuss that too much here because it can be dangerous, especially if someone has an undiagnosed heart condition, etc.)
Or an electrical BBQ lighter that uses a battery. The cheap Piezoelectric spark generators are triggered by mechanical force.
A high voltage spark is normally generated with an inductor. That's how the coil in your car creates a spark for the spark plug.
A simplified explanation is that inductors (coils) "resist changes in current". If you are familiar with Ohm's Law, "resistance is the resistance to current flow". With more voltage or less resistance you get more current.
When current flows through a coil, a magnetic field builds-up. When you first connect a DC source, a small amount of current flows as the field builds-up and then it levels-off and after the magnetic field stabilizes the current is only limited by the resistance of the wire. (This happens very quickly.)
If you suddenly disconnect power, the magnetic field collapses turning the coil into a generator. Its "trying" to keep the same current flowing but with infinite resistance (no connection). Theoretically takes infinite voltage to push current through infinite resistance, and in the real world you et high voltage, and usually a spark.
...Since relays are activated with an electromagnet, you you can get the same high-voltage "flyback" or "kickback" when power is removed. So most relay drivers have a "flyback diode" to "short-out" the current at a low voltage so you don't fry the driver transistor with thousands of volts. When the inductor becomes a generator, the current flows in the same direction but the voltage is reversed so the 'reversed" diode doesn't affect normal operation and only kicks-in with the kickback voltage.
The Arduino output, via a MOSFET will cause an air valve solenoid to open.
How simpler can you get?
Using a sparking device could cause an electromagnetic pulse to be radiated and cause your controller to lock up or fail.
Although compressed air can also be dangerous, hair spray propellant gas would be more.
The compressed air will be contained in a cylinder behind a valve.
Your hair spray propellant will be in a bottle, will you seal the end of the bottle to prevent gas leaking out before firing?
How will the Q-Tip get out?
How will you load and reload the gas?
