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SERVO HELP

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ltmhall:
Iím Building an autonomous mobile robot using differential drive and have a few questions. Iím using two continous rotation modified Hitec 422 servo motors, a Basic Stamp II (education board), two Dubro 2.75 in. wheels, and a NARP 4cm omni direction wheel.

1) If Iím using two HS 422 servo motors and a Basic Stamp II do I need an H-bridge. I was planning on connecting my servo motors to an L293 chip then connecting the L293 to a Basic Stamp, but a classmate told me I didnít need one, I could connect the servos straight to the Basic Stamp. Please Help!

2) If I need to connect my servos to an H-bridge do I actually open my modified servos and connect the two pins of the motor to the H-bridge.

3) I read a regular caster is a very great ideal for the third wheel, does anyone know a good way to mount an omni directional wheel to an aluminum chassis.

ANY HELP WOULD BE APPRECIATED

Gopher:
Your friend is right; an H-Bridge is only needed to power a motor directly, one of the advantages of servos is that they contain their own internal circuitry eliminating the need for an h-bridge.

As for how to attach the omnidirectional wheel, all I'll say is don't be afraid to improvise. Robotics really isn't brain surgery; if it doesn't work, try something else. With circuitry and motors you might blow one if you do something wrong, but when it comes to the mechanics, don't sweat it too much. If the wheel falls off, the front of the bot falls 2.75", otherwise nothing happens except you have to try again.

ltmhall:
So I would connect the servos to the spot on the board of education for connecting servo's(I saw an exampe in the What's a Microcontroller? book ). Also do I use an external 5 volts for the servos. I read somewhere its not recommended to use the regulated 5 volts from the board.

Gopher:
Not sure about the power, so I won't complicate the issue by guessing, just say that it wouldn't be much trouble to provide separate power so I'd say better safe than sorry.

I assume by "board of education" you mean the microcontroller board, in which case you are correct about connecting the servos.

dunk:
yup, you want to use a separate voltage regulator for your servos.
everything would probably work ok with the one on your microcontroller board but servos (as with any motor) can create power ripples so it's better to use a separate regulator.
you can try it without but if you find the microcontroller doesn't seem to operate as it should then power problems are the likely cause.

there's some info here on voltage regulators:
http://www.societyofrobots.com/schematics_powerregulation.shtml
http://www.societyofrobots.com/electronics_advanced_components_tutorial.shtml#voltreg
also do a search for voltage regulators.

dunk

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