It’s likely that Hackaday has a readership with the highest percentage of oscilloscope ownership among any in the world, and we’re guessing that most of you who fit in that bracket have a modern digital instrument on your bench. It’s a computer with a very fancy analogue front end, and the traces are displayed in software. Before those were a thing though, a ‘scope was an all-analogue affair, with a vacuum-tube CRT showing the waveform in real time. [Joshua Coleman] has made one of these CRT ‘scopes from scratch, and we rather like it.
Using a vintage two inch round tube, it includes all the relevant power supplies and input amplifiers for the deflection plates. It doesn’t include the triggers and timebase circuitry you’d expect from a desktop instrument though, so unless you add a sawtooth on its X input it’s only good for some Lissajous figures. But that’s not the point of a project like this one, because it’s likely even the cheapest of modern ‘scopes way exceeds any capabilities it would have even if it were fully formed. It’s a talking point and an attractive demonstration of a bit of early-20th-century physics, which probably many of us would appreciate if it were ours.
A video of the device is below the break, meanwhile we’ve taken a look in the past at the prehistory of the oscilloscope.
http://www.sparkbangbuzz.com/crt/crt6.htm
Physics at work! Beautiful! 🙂
Back in the early 1970 s I took a 1/2 credit basic electronics course with the Open University. The last part of the course involved building an oscilloscope from a kit supplied by the university. It included a timebase and the necessary amplifiers so was more complete than this one. From memory the tube was smaller than this, perhaps 1.5″. It was fun to build. Unfortunately the university wanted it back at the completion of the course.
I’ve got a scope that I can hold in my hand and uses a battery. Sure, it’s nothing fancy, but I never thought I would own a scope at all. I was excited to see probe around a C64 for the first time.
I’m old. August 1960 issue of Popular Electronics.
Somewhere around I have one of those post war surplus 2 inch tubes, this brings back a didn’t happen science fair project in the late 60’s. I had the tube from the shop class surplus bin. I think that year was a Tesla coil instead.
I’ve got an IF panoramic display for some type of airborne military application. It has a very cute two inch or so electrostatic deflection CRT. The power supply transformer inout is 115V, 400 Hz. The transformer is quite small, with magnetics obviously sized for 400 Hz operation. I thought about making a 400 Hz inverter to power the unit, but that keeps being pushed aside by other projects.
I should probably just part the unit out and repurpose the CRT for some creative fun project. The anode voltage is in the hundreds of Volts, so making a power supply with a diode multiplier rectifier would not be too difficult.