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I just joined this website and I am a 15 year old, a sophmore at Bay Path Regional Vocational Technical High School and i do not know some of these term, such as H-bridge, could someone please define some of thes words to me.

Also, I am required to compete in the science fair, and i have to do something that has to do with electronics, does anyone have any good ideas? It can not contain the uses of projectiles, pyrotechnics, animals, etc.

An h-bridge is a circuit that allows the current through the load to change direction (so you can reverse a motor). The control inputs are lower energy inputs than the actual motor currents so you can use a low power signal to control the larger motor signal. The switches you can use are relays or transistors. In case it wasn't obvious, the control inputs are the relay coils, transistor gates/bases. It's the signal that controls whether the primary high current terminals of the switch are conducting or not. For speed control you have to use transistors because relays cannot switch on and off fast enough. You PWM the H-bridge control inputs which causes the motor voltage to be PWM'd as ell, thereby controlling speed.

http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge/

lol..can't use animals. Maze following robots are always nice...not sure what's really feasible for you.

Thank you. Any ideas from anyone out there on an electronic science fair project?

I tend not to like blinking LEDs or lights and prefer something that does something physically. A maze following robot is kind of neat. It really depends on the size of the competition, your experience, and what is feasible.

since science fairs tend to be less about science and more about showmanship, I would do something that has a wow factor. Have solid engineering/science descriptions so they can't accuse you of pandering.

dang, no pyrotechnics. that takes all the fun out of it.

Some ideas - jacob's ladder, van de graf generator (static electricity and hair is always fun), voice spectrum display (talk into the mic, see your voice). I, too, like robotics. If your budget is decent ($100 or more) you can do some pretty cool stuff. Take a look at mini-sumo. that's always a crowd pleaser but you need at least 2 bots. I took my 2 bots and the ring to my son's 5th grade class and they were totally enamored by them. line followers are ok but don't have the same pizazz.

by the way, most electronic terms can be found in wikipedia with quite good explanations.

How about showing how a motor works? This can be done in a showy way by constructing a large coil of wire (like maybe 3 feet across) and then arranging some magnets to form a DC or AC motor. Make the coil of wire turn by applying some sort of electrical power that you generate with your body, like from a hand cranked AC generator or something.

electronicjuggalo said:

Thank you. Any ideas from anyone out there on an electronic science fair project?

Click to expand...

Take a look at his website and get some interesting ideas. Good luck to your project.

Science Toys

dknguyen, i agree with you, physical things tend to be more fun, but i have ADHD so i tend to like hands on things better then just posters of stuff, thank you for your recomendations.

philba, ya it is, pyrotechnics are fun, and some of those ideas seem really cool, im looking in to those, thank you

RadioRon, that might be good as well, shows you know stuff, but it wont be as hands on during the fair, but that you anyway, and i am also looking into that

eblc1388, thank you for that site, the building a computer controlled transmitter looks interesting, and that is also im looking into

Thank you all for all the help

Alright, thank you all for all of your help but i think I'm going with an idea on the website that eblc1388 posted called the free space laser transmitter, but all i need is a laptop with a serial port with a serial port, if anyone has one for sale, please, pm me with the detailed specs and a price for it. I am only in high school and am unemployed, so i cant affor to exspensive of a laptop, and my parents will not help me pay for anything, which i dont mind because it is teaching me the value of a dollar, and im not sure but I dont think the school will pay for this part of my parts, i have a computer i can trade, but its not great, its good for just going online and stuff like that, if you want that plus some money then I might trade depending on all the details of the trade. Thank you to all of you, I hope I get some good trade offers, and dont forget, just because im a teenager doesnt mean you can rip me off because I know how much I should and shouldn't pay for a laptop of ceirtain specs, I am not dumb, I'm actually quite intelegent when it comes to math, electronics, and law.

I've seen relatively simple circuits using a modulated LED light source and a receiver with an audio output. I/we do not know where you are at in terms of circuit building skills so it's hard to tell what might be possible for you. It sounds like you have a PC - can you take it to school for the demo? If so, you might do as one person suggested - display voices or other sounds with audio spectrum analyzer software. With some work it would seem that you could capture some sounds - possibly different kinds of birds - or take apart the bits of words (utterances is one term used) and display them.

Just some thoughts. Good luck.

ok, nevermind guys, i no longer need a laptop