XO-1.75 microphone socket

forster at ozonline.com.au forster at ozonline.com.au
Mon Nov 15 15:56:33 EST 2010

> From the XO-1.5 hardware spec at http://wiki.laptop.org/images/f/f0/CL1B_Hdwe_Design_Spec.pdf
> "2.7.4	External Microphone Input
> An external voltage applied to this input is limited to between 0 and 3.5 V. Inputs exceeding this range may cause excessive current to flow through a protective diode.

If there is a series resistor then the limits are higher than these, I expect. It would tolerate negative voltage till the dissapation limits of the resistor or zener are reached, presumably the resistor. Likewise if the zener is 3.5V, it would go >3.5V?

What is the zener voltage and watts, the resistor ohms and watts? P=V^2/R for the resistor, P=Vz x I for the zener


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