DC transducer signal protection

Projects General Guidance
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Hello all. This is my second arduino forum account.
I was having credential issues so I made another.
Anyway, I'm not really a "newb"

My current project is utilizing a DC amp transducer.
Supply voltage 15vdc output is 0-14vdc. The transducer data sheet shows that it can go 14v negative if reverse current is applied.
The equipment I'll be reading the amps from is a DC electric motor that can pull 150amps. I'm using a 300amp rated transducer as the data sheet shows the best linear output ramp as the transducer shows to knee pretty hard (assuming i use a 150 amp transducer)
Also for equipment longevity sake, i dont want to push a 150 amp transducer to its limits consistently. (electrohms HS300T01 is the transducer)
With electric motors having reverse voltage spikes, that would cause a revers amperage, yes?
My concern is a reverse amperage causing a reverse voltage in the signal and damaging the arduino. (analog input would potentially be significantly more than the tolerance. -?vdc to 5vdc)

My main question is:
What is the best option for keeping a clean positive signal?

Solutions I can think of:

  1. shottkey diode into voltage divider. (14v in 5v out)
    but then I would have to account for the voltage drop across the diode. Unless I used a duplicate circuit from the 15v to the AREF??

  2. some type of opAmp situation.

THANK YOU FOR YOUR TIME!!

2

Microprocessor inputs have protection diodes for both negative voltage inputs, and positive voltages higher than Vdd (supply voltage), but the diodes cannot tolerate more than about 1 mA of current.

A 15K resistor in series with the input should provide adequate protection from swings of -15 to 15V, but of course if the input is analog, you can't measure a voltage higher than Vdd (or the chosen analog reference voltage), so a voltage divider is probably required. That will offer additional protection if designed correctly.

A 100 nF capacitor from input to ground will help with spikes.

1 Like
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Excuse me for butting in here, but the specs and the wiring diagram both show the power is + and - 15 volts. Where are you getting the other 15 volts from?

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That is against forum rules!

1 Like
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@horkus_flux ,
Please see the message I have sent you, you are not allowed multiple accounts.

Please log in using your other account and continue with this topic from that account.

Thank you.

@pert ,
Are you able to transfer ownership of this topic to the OP's original account please?

Thank you.

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