Author Topic: FSK to USB Interface - resistor required??  (Read 1158 times)


  • Member
  • *
  • Posts: 3
    • View Profile
FSK to USB Interface - resistor required??
« on: 21 May 2020, 12:08:51 »
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??


  • Administrator
  • Top Member
  • ***
  • Posts: 184
    • View Profile
Re: FSK to USB Interface - resistor required??
« Reply #1 on: 22 May 2020, 10:15:55 »
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.'