Retrotechtacular: Tube Amplifiers

retrotechtacular-how-tube-amps-work

It’s hard to beat this vintage reel for learning about how vacuum tube amplifiers work. It was put together by the US Army in 1963 (if we’re reading the MCMLXIII in the title slide correctly). If you have a basic understanding of electronics you’ll appreciate at least the first half of the video, but even the most learned of radio enthusiasts will find something of interest as they make their way through the 30-minute presentation.

The instruction begins with a description of how a carbon microphone works, how that is fed to a transformer, and then into the amplifier. The first stage of the tube amp is a voltage amplifier and you’ll get a very thorough demo of the input voltage swing and how that affects the output. We really like it that the reel discusses getting data from the tube manual, but also shows how to measure cut-off and saturation voltage for yourself. From there it’s off to the races with the different tube applications used to make class A, B, and C amplifiers. This quickly moves onto a discussion of the pros and cons of each amplifier type. See for yourself after the jump.

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TOBY: reel mower bot evolved

[Grayson Sigler] rolled out a new version of his robotic mower which he calls TOBY. The previous design added motors to a reel mower but he had trouble with traction. The new design is more of a utility robot platform that is used to tow the reel motor behind it. With better wheels, a much more stable base, and plenty of power this is a significant improvement.

His parts order came since we last checked in and he now has RC fully implemented. Check out the video after the break.

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Remote control reel mower

Challenged by hot days and steep turf [Grayson Sigler] modified his reel mower to use electric motors. The end product will be radio controlled but he lacked the necessary parts to make it wireless right now. Not to be deterred, he used a wired controller for prototyping and testing that should be easily replaced once the parts arrive. Sadly, the grade of his yard causes the small wheels to slip so he tried inserting screws into the tread for added traction. The small mower lacks the weight and footprint that the Lawnbot400 enjoys. That being said, solar charging is one of the future goals so this build, which he named RoMOW, wins out on the green scale. We’ve included the prototype video after the break that shows the blades spinning away.

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