Here’s a way of transmitting audio that makes it virtually impossible for someone else to listen in. Instead of sending radio waves bouncing all over creation, this uses the focused light of a laser ...

Here’s a way of transmitting audio that makes it virtually impossible for someone else to listen in. Instead of sending radio waves bouncing all over creation, this uses the focused light of a laser ...

The intercom circuit described here uses two transistors, an audio transformer, and a few passive components in addition to condenser microphone and low-wattage speaker (refer Fig. 1). The complete ...