swapping polarity electronically

[atf1084]

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

 

[dknguyen]

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

THere are 3 pages to this website.

 

[mvs sarma]

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

What type of motor, AC, DC, magnetic or with field coil? if you give the details, it would be easier to discuss.

 

[Hero999]

Well the thread is entitled "swapping polarity" so I'd assume it's a DC motor.

 

[mvs sarma]

1. If the motor has permanent magnets, just input voltage reversal would do.

2.In case the motor has excitation from the input voltage, then, voltage reversal as indicated above has to be be followed by a bridge rectifier in the excitation circuit. I would like to thank a friend of mine Mr M.V.Rao has has extended this idea to my mind for the first time, around 15 years back.

 

[atf1084]

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?

 

[Hero999]

I'm not sure what you're trying to do.

All I know is that permanently connecting R2 and R4 to ground is a bad idea becase the transistors will be destroyed when either Q1 or Q3 are turned on.

 

[atf1084]

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

 

[rebirth of sands]

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

 

[atf1084]

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?

 

[Hero999]

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