- Sun Feb 12, 2006 7:53 pm
#9764
Hello,
A friend of mine built a project using Lego Mindstorms that raises and lowers a weight on a string around a shaft turned by the lego motor. It works well, but the lego motor is not strong enough to pull the final load size. He has built an assembly using a 1.5 amp motor that can easily pull the weight. I am trying to help him interface the rcx to the bigger motor.
I'm not sure how much current the RCX can provide, but its certainly not designed to operate in the range of the big motor. Also the rcx seems to put out between 7 and 8 volts, and the big motor is running at 12. I figured that I could just use the rcx to control an H-Bridge that would then drive the motor.
My questions, then, are:
Does this seem like the correct aproach?
Is it fine for the bridge to connect a lower voltage and lower amp input to a higher volt and higher amp output?
What is the most direct route to getting a bridge that can handle this load (ie. can someone recomend a good IC to use?, should i build one from TIP120s, does somewhere like sparkfun have a relatively cheap (<= $30) board for this?)
Any input would help, thanks. Justin
A friend of mine built a project using Lego Mindstorms that raises and lowers a weight on a string around a shaft turned by the lego motor. It works well, but the lego motor is not strong enough to pull the final load size. He has built an assembly using a 1.5 amp motor that can easily pull the weight. I am trying to help him interface the rcx to the bigger motor.
I'm not sure how much current the RCX can provide, but its certainly not designed to operate in the range of the big motor. Also the rcx seems to put out between 7 and 8 volts, and the big motor is running at 12. I figured that I could just use the rcx to control an H-Bridge that would then drive the motor.
My questions, then, are:
Does this seem like the correct aproach?
Is it fine for the bridge to connect a lower voltage and lower amp input to a higher volt and higher amp output?
What is the most direct route to getting a bridge that can handle this load (ie. can someone recomend a good IC to use?, should i build one from TIP120s, does somewhere like sparkfun have a relatively cheap (<= $30) board for this?)
Any input would help, thanks. Justin