Resistors

How would I figure out the resistor I would need for this? :

Could you give us a datasheet? A part number, even just a brand?

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How would I figure it out?

Why do you think you need a resistor and where are you proposing to put it?

Yeah I don't think you need a resistor for that.

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This is not the Virtuabotix forum.
Ask there, if you cannot find information, but search first, please, and don't tell them I sent you :wink:

That module, from what I can see searching around, has a trigger input and echo output, both logic signals so no resistor is needed. Arduino Forum