Hi

I have a motor that i want to change direction electronically.. i assume i need a few transistors or is there a general available IC that can do that? if not how would i setup the transistors to not cause a short circuit

http://www.modularcircuits.com/h-bridge_secrets1.htm

THere are 3 pages to this website.

i have setup the following H-Bridge circuit and it works fine,
when i connect r2 to gnd and r3 to +vdc the motor spins one way. when i connect r4 to gnd and r1 to +vdc it goes the other... i have another circuit that uses a common ground and has 2 outputs for +vdc with the idea of changing the direction of the motor based on which output is active... i tried permanently connecting r2 and r4 to ground but the circuit did not work at all.. i tried using transistors on r2 and r4 so only one is connected to ground at a time and it still does not work, is there is a way to achieve my desired result?

ok, basically, i have a common ground and 2 x 4.5v DC... Only one will be on at a time, i have a dc motor and I want the motor to change direction based on which of the 4.5v DC's are on, and of course stop when both are off

i have already setup the h-bridge above, but to change direction requires 2 actions (+vdc connected to low side and common connected to high side) i want to find a way to do this with only one action (which one of my 2 +vdc's are on)

please let me know if i am making absolutely no sense

wee...for changing the direction..i think icL293D/L293B should do the work....i didnot work with it but read it ...

i would really like to use an ic to do this, i have checked with the two electronic chains in australia (Jaycar and Dick Smith electronics) and neither of them stocks any type of h bridges. does anyone know any reputable online electronic stores that ship to australia?