Magnavox Portable TV Oscilloscope! - Page 1
Forum section: electronics / projects

author: AviatorLj
author_rank: Contributor
timestamp: October 27, 2015, 01:21:07 am
content: I made an oscilloscope a few days ago out of a $2.98 (American Dollars) Magnavox portable TV. It was pretty easy. If you're playing along at home, just look for four wires soldered next to each other on the CRT and clip each from the board, not the CRT. Mine were labeled WD 2 through 5 or something. Yellow and Green are the common Vertical wire colors and Red and Blue are horizontal. Solder each to a banana plug female port and play around with it. I unfortunately had only two banana plugs on hand, so I had to improvise with some alligator clips. I made a couple Lissajous figures with a stereo headphone male to male plug and the following link:http://onlinetonegenerator.com/binauralbeats.htmlThe Online Tone Generator is not perfect (Its sine waves are fine, triangles are OK, square and sawtooth don't work well), but the binaural beats generator makes fine Lissajous figures. Of course you can also use a mono plug and double up the banana plugs and make an ellipse. I will try to post some video soon.

author: AviatorLj
author_rank: Contributor
timestamp: October 27, 2015, 01:22:33 am
content: More pics

author: SteveLy
author_rank: Regular Contributor
timestamp: October 27, 2015, 02:01:53 am
content: That's neat. Black and white TVs are way better than colour for this. How sharp can you get the trace?

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: October 27, 2015, 04:22:09 am
content: Fun stuff! Always good to see more aviators, too!

author: crispy_tofu
author_rank: Super Contributor
timestamp: October 27, 2015, 06:30:28 am
content: Very neat!

author: AviatorLj
author_rank: Contributor
timestamp: November 02, 2015, 03:28:20 am
content: I made a YouTube video on this. It can be found here:https://youtu.be/QA1ODE36r7E

author: Twistedsnail
author_rank: Contributor
timestamp: November 02, 2015, 11:56:04 am
content: That's really cool!If I see a CRT TV I'll definitely grab it.I'd like to see the the sweep to make it time domain.What sort of voltage range does the tube respond to?

author: AviatorLj
author_rank: Contributor
timestamp: November 03, 2015, 12:06:59 am
content: Quote from: Twistedsnail on November 02, 2015, 11:56:04 amSame as headphone audio voltage from a computer or phone. I believe it's 5v or something, and a 9v battery makes the dot go off the screen.

author: Circlotron
author_rank: Super Contributor
timestamp: November 03, 2015, 11:26:23 am
content: Somewhere on this forum the other day there was a thread talking about an amplifier that drives a loudspeaker with acurrentwaveform rather than avoltagewaveform. You should try that kind of amplifier to drive the deflection coils of your TV because the amount of beam deflection varies according to the amount of current in the coils, not the voltage applied to them.

author: AviatorLj
author_rank: Contributor
timestamp: February 19, 2016, 12:42:58 am
content: Quote from: Circlotron on November 03, 2015, 11:26:23 amThat's interesting...Oscilloscopes do normally use voltage to make the waveform of course, but adding current functionality would be cool to see.

author: Circlotron
author_rank: Super Contributor
timestamp: February 19, 2016, 07:47:07 am
content: What I mean is, a conventional scope take the input signalvoltageand amplifies it and applies thisvoltageto the crt deflection plates. With your tv scope you need to turn the input signalvoltageinto a correspondingcurrentand apply thiscurrentsignal to the deflection coils.Or maybe you already realised what I meant; not sure.

author: calexanian
author_rank: Super Contributor
timestamp: February 19, 2016, 09:48:36 pm
content: Very cool.

author: RobertBG
author_rank: Regular Contributor
timestamp: February 21, 2016, 08:35:34 am
content: That's a neat project and I just might have to make one with my daughter.I also subscribed,you guys really have a good start at a nice channel going there.