Tulley Family Tinkering Lab Website

The Science Fair

by on Mar.03, 2010, under science fair

Robbie has a science / invention fair on the 17th and 18th of March (2010). He has been coming up with a whole bunch of ideas, and finally settled on one — a gadget that turns on his light in his room when his alarm goes off. With this, he will be more likely to get up and not just go back to bed.

Now we are poring over schematics for a whole bunch of circuits — sound detection — signal latching — servo or motor control. We’re pondering a whole bunch of electronics questions — is a 2N3904 transistor close enough to a BC548B to work in his circuit? If not, how does one modify the circuit to make it fit? (Radio Shack only had one type of amplifying transistor — NPN or PNP, I do not recall which). How do you interpret the markings on a capacitor?

Putting it all together will be fun too.
Links:
http://www.rev-ed.co.uk/docs/picaxe_sound.pdf
http://www.reconnsworld.com/audio_sounddetectlatch.html
http://www.ecelab.com/circuit-monostable-555.htm
http://www.datasheetcatalog.org/datasheet/fairchild/2N3904.pdf
http://www.philohome.com/sensors/gp2d12/gp2d12-datasheets/bc548.pdf
http://www.philohome.com/sensors/gp2d12/gp2d12-datasheets/bc558.pdf

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