Sucess!!

Let's Make Robots
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1

WEll i'll start off with i'm lazy. that being said nothing is more exciting then doing soemthing right when i finally try. This afternoon i hooked up an old pc speaker i salvaged from work.

 

The good news: it works, and generates tones based on input from my ir sensor.

the bad news: its awfully quiet, i would think it has to do with being a pc speaker and being driven by 5v- whatever the darlington takes out of it.

 

now the decision: do i hook up a second power supply? or search for a speaker ment to be driven off of 5v?

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Speakers vs. Voltage

Being electromagnets, speakers don’t really care about voltage. I could pull a speaker out of a PC and make it work on 100V. Conversely, a speaker from a PA could be made to work at 5V.

Here’s the deal: your speaker (probably) has an impedence of 8 ohms. You want to drive it with 5V. V=IR, so I=V/R=5/8 = 0.625A, so in order to get “full volume” you need to be able to drive it with 625 milliamps. Your PIC only sinks about 25mA, but there’s this darlington everyone keeps banging on about.

Can anyone tell me the configuration of the transistor? A citcuit diagram? A manual?

I’m sure I posted a similar comment elsewhere…
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help?

http://www.electronicsinschools.org/page.php?ps=2&p=11

 

i think that’s what we are looking for?

 

originally linked from the picaxe support chips article that psy wrote awhile back.

 

thinking back i vaguely remember hearing about impedance and 8 ohms vs 4 ohms…

 

so much to learn.

 

upon further inspection i dare say this is the spec sheet(s) for the chip i have in my project board:

http://focus.ti.com/lit/ds/symlink/uln2803a.pdf

i just breifly looked over it i think i saw a max of 500ma…

4

There are speakers

There are speakers everywhere, in everything.

Get loads, don’t mind all the clever stuff, just find one that fits for the purpose!

(I am too stupid to understand the I=Ur+IN - and I don’t care, just work, speaker, or I’ll find another!)

There is a huge difference in the loudness of the speakers. Huge!

5

i do like your way of
i do like your way of thinking!

6

Yuck
I can’t stand his way of thinking. He’s more of an artist than a scientist. However, they appear to be a good compliment.

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I am just more into making

I am just more into making the sound than wondering about the Ohms and Urin!

Knowing why it does not work does not make it work.

Just realizing that less of them Ohms is cooler for more sound on the Picaxe is enough to go and find some wih less of them Ohms :slight_smile:

- ANd hey - Us artists are really happy that we have the clever guys to do the thinking, thanks :smiley:

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"Urin"?

Is “Urin” a measurement of the number of coffee-breaks the electron-gnomes take?

My problem is there are an infinite number of ways to make something not work.

“Artists” do thinking, too. It’s just much less structured.

9

Noe, maen… no thinkin.
Noe, maen… no thinkin. Wedjost feel, younou? Floouu! Ledid live!

10

Translated this means…
Translated this means… “WOW BOA! You’re smarter than I am. I bow to your superior wisdom!” I may be a bit off he spaeks a dialect I’m not used to…

11

Shhhhh!
Shhh! I know!