HomeНаука и техникаRelated VideosMore From: smbakeryt

Magic Eye Tube part 1: Building a magic eye tube kit from eBay

85 ratings | 7377 views
I have some projects that I wanted to integrate magic eye tubes into, so I started experimenting by buying some cheap DIY kits from eBay. In this video I assemble one of the kits, try it out, and hook it up to my pilotuner radio.
Html code for embedding videos on your blog
Text Comments (11)
Ron Thompson (6 days ago)
Could you give us the eBay web site this is on ,what the name of the kit.
videolabguy (16 days ago)
Kind of late to comment. But, R1 and R2 are to balance the AC across the heater and keep hum from coupling into the cathode.
JORGE GUERRERO (19 days ago)
the input audio comes from the input to amp or the output to speakers?
Santiago La Rosa (1 year ago)
Hello, Mr Scott. I saw this video because i am looking for help with my magic eye vu meter. I bought the same kit as you show in this video, but i don have your old "pilotuner t601" that i suppose have an hi impedance output. My question is: how much is the input impedance of this circuit? how can i test it with a 8 ohm output radio? can i do that? Best regards... Santiago.
videolabguy (16 days ago)
As long as the driving impedance, output, is lower than the input impedance then it will work just fine. Also to the type of questions you asked. Just try it. You can't really do too much damage. Tubes will take a beating that would instantly kill a transistor or IC.
Jianghong Shen (1 year ago)
This a batter https://item.taobao.com/item.htm?spm=a1z10.5-c.w4002-3456411886.23.2f669dfb4ZDygW&id=15228685211
qu1en (1 year ago)
if you ignore the npn and imagine an AC signal at the two diodes they will only turn ON when syncing current, eventually the holding cap at the grid will charge up to a negative voltage. Since the magic eye works around 0 to -22V at the grid, and the audio signal is too low voltage, the transistor is needed for gain. The transistor operates in common emitter where the emitter will sit at DC 30V-0.7V. The AC audio signal is then coupled onto the base-emitter as you mention with a large AC gain from the NPN (the 47k resistor acts as the load resistor). As more AC current is drawn from collector to emitter the holding cap at the grid will go more and more negative and go up and down with one end of the AC signal. This sort of transistor circuit would be used as a basic class A amplifier design in common emitter (for those that want to understand it better). That is how I interporate this schematic. Thanks for sharing I might try it.
Moonwalker917 (1 year ago)
This kind of kit go as low as 5€ on ebay. I bought one of these solely to get the tube for a radio I was fixing. I'm really interested in your variable HV supply. Are you planning on making a video on it, if not, would you mind sharing a rough schematic of it's working principle?
Decir La Verdad (1 year ago)
I gusta el cuchara de coke...lol
PelDaddy (2 years ago)
Thanks for sharing. Nicely done. Did you end up using that 82K resistor, or did you have to swap it for a 47K? I just finished restoring one of those Pilot Tuners myself, fun project. Did you just have the output form the Pilot connected to the input of the Magic Eye board (and Y'ed off to the audio amp), or did you need any other components in between? Have been a fan of your blog for a while, BTW. Thanks for sharing.
Retro Starship (2 years ago)
Cool, ill try and find it on ebay and order one as well, Thank you for sharing.

Would you like to comment?

Join YouTube for a free account, or sign in if you are already a member.