FSK to USB Interface - resistor required??

[orion_jb2001]

Hi all,

Just doing some tiding up with the scanner, appreciate the need for the resistor of a discriminator tap to protect pc sound cards etc, but do you need to put in a resistor for a usb interface??

[Discriminator]

The main reason for using a resistor is to protect the receiver IC in the scanner. From the FAQ -

'What's the function of the resistor?

Connecting or disconnecting an interface to the discriminator output might cause a short-circuit. The limiting resistor prevents the discriminator IC from being loaded or damaged. Further to that, it prevents your PC's microphone or line input from being overloaded.'