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 ...

You probably have needed to match impedances and levels from time to time. Perhaps you want to connect a consumer computer’s sound card to your console; or you need to lower a balanced output level to ...

Having built a number of vacuum tube output transformer-less (OTL) amplifiers in recent years, it seemed as though it might be a good idea to try combining older with newer technology and using both ...