Category: Hackaday

via HACKADAY: Eight Transistor Stereo Amplifier From The Days Of Yore

Reading an article about the first transistorized Hi-Fi amplifier, [Netzener] got the itch to make one. But what to use for the starting point? Enter an old Radio Shack P-Box stereo amplifier kit. After a few modernizations and tweaks, the result is an 8-transistor stereo amplifier that’s aesthetically pleasing, sounds great, and is fully documented. The Radio […]

via HACKADAY: Philo Farnsworth, RCA, and the Battle for Television

The parenthood of any invention of consequence is almost never cut and dried. The natural tendency to want a simple story that’s easy to tell — Edison invented the light bulb, Bell invented the telephone — often belies the more complex tale: that most inventions have uncertain origins, and their back stories are often far […]

via HACKADAY: Bandpass Filters from the CNC Mill

A bandpass allows a certain electrical signal to pass while filtering out undesirable frequencies. In a speaker bandpass, the mid-range speaker doesn’t receive tones meant for the tweeter or woofer. Most of the time, this filtering is done with capacitors to remove low frequencies and inductors to remove high frequencies. In radio, the same concept […]

via HACKADAY: Ham-designed Gear Used in Thailand Cave Rescue

Unless you live in a cave, you’ve probably heard a little about the thirteen people — mostly children — trapped in the Tham Luang Nang Non cave in Thailand. What you may have missed, though, is the hacker/ham radio connection. The British Cave Rescue Council (BCRC) was asked for their expert help. [Rick Stanton], [John Volanthen] and […]

via HACKADAY: The History and Physics of Triode Vacuum Tubes

The triode vacuum tube might be nearly obsolete today, but it was a technology critical to making radio practical over 100 years ago. [Kathy] has put together a video that tells the story and explains the physics of the device. The first radio receivers used a device called a Coherer as a detector, relying on two tiny […]

via HACKADAY: Portable Ham Radio Design Fosters Experiments

[Charlie Morris] has been busy building a portable ham radio rig and documenting his progress in a series of videos. You can see the first one below. There’s four parts (more if you count things like part 4 and part 4a as two parts) so far and it is always interesting to see inside a […]

via HACKADAY: The Colpitts Oscillator Explained

The Colpitts oscillator is a time-tested design — from 1918. [The Offset Volt] has a few videos covering the design of these circuits including an op-amp and a transistor version. You can find the videos below. You can tell a Colpitts oscillator by the two capacitors in the feedback circuit. The capacitors form an effective capacitance for […]

via HACKADAY: Biasing That Transistor Part 4: Don’t Forget the FET

Over the recent weeks here at Hackaday, we’ve been taking a look at the humble transistor. In a series whose impetus came from a friend musing upon his students arriving with highly developed knowledge of microcontrollers but little of basic electronic circuitry, we’ve examined the bipolar transistor in all its configurations. It would however be […]

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