CAMBRIDGE ELECTRONICS LABORATORIES best sellers

#1 Black Magic Telephone CAMBRIDGE ELECTRONICS LABORATORIES Black Magic Telephone Ringing Generator Sine Wave 12 Vin 86 Vout 20 Hz

$33 on Ebay

#2 Telephone Ringing Generator CAMBRIDGE ELECTRONICS LABORATORIES Telephone Ringing Generator Sine Wave 12 Vin *variable frequency output*

$33 on Ebay

#3 Quiklink Two Way Automatic CAMBRIDGE ELECTRONICS LABORATORIES Quiklink Two-Way Automatic Ringdown Module (telephone hotline)

$94 on Ebay