Subject:
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Re: 5VDC Voltage Regulation
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 28 Sep 1999 15:32:46 GMT
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Viewed:
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1088 times
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In lugnet.robotics, Michael Gasperi writes:
>
> Jacob Schultz <dungeonmaster@get2net.dk> wrote in message
> news:FIrMLo.H8K@lugnet.com...
> > Normally you apply a diode to swallow this current, so that the voltage
> > cannot become higher than 0.7 volts.
>
> A "freewheeling" diode is a good idea generally, but the RCX must already
> have diodes built into the driver IC. It has to turn on and off the motor
> hundreds of times a second to generate PWM.
> http://www.melexis.com/site/10402/f_10402.htm is the driver data sheet, but
> it doesn't show the diodes.
You can't have the diodes on the motor because it goes in both directions.
If you put a diode out there, you would have a dead short in one of the
directions. Such things need to be built into the H-bridge, not the motor
leads. So, I seriously doubt that this relay circuit will need a flyback
diode, this will already be covered in the H-bridge, which was designed to
handle an inductive load (obviously). Adding a diode will simply create the
possibility of shorting the output if the reverse voltage is applied (like,
putting the connector on the other way?) I think the diode is bad idea
entirely.
DLC
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Message is in Reply To:
 | | Re: 5VDC Voltage Regulation
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| Jacob Schultz <dungeonmaster@get2net.dk> wrote in message news:FIrMLo.H8K@lugnet.com... (...) A "freewheeling" diode is a good idea generally, but the RCX must already have diodes built into the driver IC. It has to turn on and off the motor (...) (25 years ago, 28-Sep-99, to lugnet.robotics)
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