Candle Snuffer with Arduino and 9V Battery

another side view of snuffer

Having the urge to make a ‘pointless invention’,  I made a candle snuffer from a DC motor off an old helicopter, a 9V battery, and Erector set pieces. Basically, a fan blade attached to the motor and wired to a pushbutton sends a sufficient gust of air to blow out the flame of a small candle. I made two different versions of the snuffer, one with a only a 9V battery and one with an Arduino powered of a 9V battery, with the motor connected to 9V.

The snuffer basically has a little tray for a candle, with a fan pointed down at the top of the candle. A breadboard is mounted upright on the side, and the 9V battery is stowed under the tray. Below is a view of the whole thing lying on it’s side without the candlelaying flat

Arduino Micro Candle Snuffer

When I first got the idea for a candle snuffer, I immediately thought using the Arduino Micro with a fan and allowing for time delays, temperature sensing for ‘overheat’ shutoff, and a photoresistor to detect if the candle is lit or not. The first thing I made was the breadboard mount and the candle tray out of Erector set pieces, and then I attempted to add the photoresistor, near the candle. However the heat from the candle would have likely damaged the photoresistor.

Getting the motor to spin fast enough to blow out the candle flame was a challenge with Arduino due to power constraints and transistor problems. I first tried direct drive off an Arduino pin’s 5V, but that did not make the motor spin nearly fast enough. Then I tried driving the motor with 9V via PNP transistor controlled by the Arduino, which, after a couple transistor overheats, still did not allow the motor to spin fast enough maybe due to voltage drops and such. My final version uses a 5V relay which seems to work really well. The fan spins more than fast enough using the relay. I’m not a huge fan (no pun intended) of relays because they can be difficult to wire and take up a lot of space on the breadboard. I had to tape my relay in place with my bright yellow electrical tape to keep it from popping out.arduino_candle snuffer wiring

Because of all the frustration with driving the tiny little fan motor, I didn’t do much with the Arduino software side of things. You can check out the code I used here, which basically sends a gust of air at the candle flame when the button is held down. I didn’t add a time-delay or other sensing capabilities yet, though I may not because this is kind of already a benched project.

In my wiring, the 9V battery is connected to the Arduino’s Vin pin, and its ground is tethered to the Arduino’s ground. The relay turns on and off when it gets a signal from the Arduino. The fan runs off of the Arduino’s constant 5V pin. I’m not sure how this differs from direct motor drive from a pin, but the fan spins moves much faster.

Candle Snuffer Powered Off of 9V

Halfway through building the Arduino Micro version, I tore it all up and resorted to a pushbutton wired between 9V and the motor. When you press the button, the fan comes on and blows out the candle. I did look into using a 555 timer IC to try and create a 30 minute time delay until the candle is snuffed, but that ended up being a little complicated since I don’t have all the capacitor values. Ironically, this version of the candle snuffer does exactly the same thing as the Arduino Micro version.

The schematic is below. It’s quite simple.

9v circuitpic candle snuffer
side view of snuffer

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Two Possible Pi Cases

my two pi case ideas

I’ve contemplated making a different case for my Raspberry Pi Model B and I’ve come up with two different ideas.

Case Option #1: A Heavily Decorated Cardboard Case

pi in cardboard caseI still have the cardboard box that my current Model B plastic case came in, and I could use the pre-sized cardboard box to make a simple dust case for my Pi. I would just have to cut some holes in the box for the peripherals, and maybe add some foam padding on the inside bottom. The fun part would be embellishing the outside of the case with glitter and unicorn stickers. (okay, I would NEVER put unicorn stickers on a Pi EVER, that would be a crime) I could add some kind of cool artwork with circuit symbols on it.

Of course, it would be an amazing pun to buy a mini raspberry pie to use the box it comes in as a Pi case, but, alas, I’ve never seen one in the store.

Case Option #2: Re-purposed Portable Cassette/Radio Player Case

cassette radio playerMy other case idea is using to put the Pi in an old AM/FM radio and cassette player that I found. The cassette function never worked on it, so I took it apart, to discover that the Pi fit quite nicely in it. The radio function still works, and I haven’t decided if I should leave it for an extra function to the case, or remove to leave more room for the Pi. It does fit on top of the radio circuit quite nicely, but I would have to add some kind of insulator to seperate the radio circuit from the Pi and I would only be able to run the Pi headless because there’s not enough space to attach any peripherals.

I could remove the radio circuit completely or building my own smaller radio, but I’m probably better off using the Pi as an internet radio.There would be plenty of room to also add a Liion battery and turn it into a completely wireless case for the Pi to run it headless.

pi inside radio player

I’ll be working on one of these soon and I’ll post a image of what I end up doing!