DIY Electronic Birthday Blowout Candles

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Adambowker98 says: Apr 15, 2012. 3:28 PM

So, um.... How do you make it? All the steps are blank!

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Lithium Rain says: Apr 26, 2011. 11:34 AM

Hey, you have a bunch of blank steps on here. Nobody can figure out how to make this. It's very sad T_T

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purpulhaze says: Apr 13, 2010. 2:41 PM

Do i need to be a pro member to see this instructable?

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watermelonhead says: Aug 14, 2009. 9:10 AM

pics pwease?

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T3h_Muffinator says: Jul 11, 2008. 5:20 PM

This looks awesome! I'm just wondering - where's the analog input pin of the uC? I looked at your schematic and it seems as if you just have it in a resistor network on VCC.

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cedtlab (author) in reply to T3h_MuffinatorJul 11, 2008. 11:03 PM

Hi, Thanks for your comment. Tiny45 has several analog input pins. Pin1 (is PortB5 and is also ADC0 input ) is one of them. We used that to read the voltage at the junction of R3 and R4. R3 is the thermistor and R4 is a fixed value resistor. Since the other end of R3 is grounded, as the thermistor cools off, its resistance increases (the thermistor is an NTC, i.e. has a negative temperature coefficient) and so the voltage at the junction of R3 and R4 increases.

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bikeNomad in reply to cedtlabFeb 22, 2009. 2:08 PM

Why bother with the heater (R2)? It's a big load on the battery (though so are the LEDs...) and shouldn't be needed. Did you try using self-heating?

By using the self-heating of the thermistor itself you should be able to detect the cooling caused by air movement.

Just run enough current through the thermistor that it heats up a few degrees above ambient (and not enough to damage it), and look for quick changes in the port voltage.

You'd be best off to use a much smaller thermistor, though (perhaps something like this cheap thermistor.

bewakoof says: Jul 11, 2008. 9:07 AM

Awesome work and extraordinary description

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Derin in reply to bewakoofJan 2, 2009. 7:14 AM

BOLD

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Derin in reply to DerinJan 2, 2009. 7:14 AM

'[linktest:// test for links]'

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emuman4evr says: Sep 20, 2008. 8:16 AM

Whats a thermistor, never heard of that before.

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cedtlab (author) in reply to emuman4evrSep 20, 2008. 9:36 AM

A thermistor is a temperature dependent resistor.
More information is here:

http://en.wikipedia.org/wiki/Thermistor

Thanks,

driesyo says: Sep 20, 2008. 6:57 AM

(removed by author or community request)

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=SMART= says: Jul 29, 2008. 5:02 AM

Hahahahahaha Cool !!

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nickstewartroc says: Jul 17, 2008. 8:38 PM

This is AWESOME i think i will have to make this and put it on my birthday cake since its coming up in a month(August 12)

Culturedropout in reply to nickstewartrocJul 23, 2008. 7:31 AM

Just be sure to use lead-free solder and other components. It'd suck to get lead-poisoning on your birthday... ;-/

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cedtlab (author) in reply to CulturedropoutJul 23, 2008. 8:37 AM

what we are planning to do is to put the electronics and batteries in a food grade plastic box with just the LEDs and sensor sticking out.

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nickstewartroc in reply to cedtlabJul 23, 2008. 10:18 AM

Thats a good idea, i think that is what ill do for my cake :)

gauravrewatkar311 says: Jul 20, 2008. 1:43 AM

good very interesting !!!!!!!!!!! all my regards go to the " IDEA MAN " GREAT THINKING i am expecting something new next month also!!!!!! great job

joshbond_2007 says: Jul 17, 2008. 4:41 PM

you mean 4x1.5volts

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Gadre in reply to joshbond_2007Jul 17, 2008. 9:19 PM

I mean four re-chargeable (NiCd or NiMH) batteries which are typically 1.2V each, so thats 4x1.2 volts Using 4x1.5V batteries (for example the alkaline ones) would not be advisable since the microcontroller cannot handle 6 volts.

papiya says: Jul 14, 2008. 2:59 AM

cool..so the modela makes ready to use boards now!..gr8..lots of time saved

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sotsirh194 says: Jul 12, 2008. 5:41 AM

Just so you know this was featured in one of my electronics design magazine. It was way in the back and there wasn't much instruction on how to build it.