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Reverse polarity Question

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Sam Neall

Sam Neall

Mechanical
Mar 26, 2020
32
I have a small diffuser driver that I would like to hook up to an Arduino motor shield .
The problem is that this shield can switch polarity on it’s outputs and the diffuser driver will burn out if polarity is switched on its input. So basically if I mess up a small part of the code, the diffuser driver will burn out. Can I connect the positive the diffuser driver to only one of the outputs on the shield then just use a completely different ground. So, if the motor shield decides to switch polarity, it’ll just be going to a pin that has nothing connected to it.
Is this design problematic? If it is, what is another solution to deal with this.
 
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Put a bridge rectifier between the output and the polarity sensitive device, or use an inline diode.

Bill
--------------------
"Why not the best?"
Jimmy Carter
 
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I have some 50V 1A rectifier diodes laying around. Will they work or will I have to order different components? I’m assuming I would just put the rectifier on the negative and only let electricity pass back into the driver. Is that correct?
 
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image_g4qhyj.jpg

image_obxrcz.jpg
 
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One diode that may be in either line to prevent reverse polarity from getting to the load.
Use four to make a bridge and your load will accept either polarity.

Bill
--------------------
"Why not the best?"
Jimmy Carter
 
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So the bridge will just take whatever shield pin that’s putting out a positive signal and automatically link it to the positive terminal of the driver then vice versa for the ground? I never knew you could do that. Also the output of the driver is 1.2 amps nominal 3 amps max. Would the bridge be able to handle that?

@IRstuff it should be fine because I’m going to run it at a lower voltage anyways.
 
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3 Amps max?
I have some 50V 1A rectifier diodes laying around.
Will they work? No
Will I have to order different components? Yes

Bill
--------------------
"Why not the best?"
Jimmy Carter
 
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A single diode = -.7 volts
A bridge rectifier = 2 x .7V = 1.4 Volts drop.
Your choice.

Bill
--------------------
"Why not the best?"
Jimmy Carter
 
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OK. I didn’t know if they shared the current or not. I am fine with a voltage drop because as I said I’m going to be running the driver on much lower than 12 V. So, assuming that you recommended that I use a rectifier, you’re saying that the idea I proposed wouldn’t work? The reason I’m so hesitant to order parts because they take a while to ship because of Quarantine.
 
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If I were to buy one, does the voltage rating matter as long as it’s above the voltage that my circuit operates on? I can only find 600 V bridge rectifiers.
 
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The listed voltage is how much they can withstand while blocking current. The actual characteristics are found in the data sheets that are available from most suppliers.
 
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RMS voltage is 420 so I should be good getting that one.
 
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Not sure why the voltage is a concern; your motor shield only puts out 12V. You could save a few pennies.

This doesn't sound work related. Hobby postings should be posted in forum1528



TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
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