Mini TV / Oscilloscope

Hi, I'm going to show you how to make a tiny TV/Oscilloscope. You will be working with a Cathode Ray tube which requires high volts and high pressure vacuums, so be careful. To build this you need patience.

Please rate my instructable or leave questions. They will be answered.

This is an old instructable I accidentally deleted a while ago and managed to find via a link deep in the interwebs. The TV has since been lost, but I plan on making a new and better one.

Step 1 Get All The Stuff

You will need...

Tools:
+ A soldering Iron/Gun*
+ Solder*
+ A small phillips screwdriver*
+ A Hot Melt glue gun
+ Hot Melt Glue
+ Scissors

Electronic Items:
+ 3 DPDT switches*
+ Reasonably thin wire*
+ Two nine-volt battery snaps*
+ A Relay*
+ An LM386 audio amplifier IC*
+ A 100k Potentiometer*
+ A 10uf Capacitor*
+ A Small Speaker*
+ Female AV Jacks°

Other Items:
+ An old video camera {circa 1990}
+ A craft box to build it in

*can be bought at radioshack etc.
°salvaged

Comments

[spystealth1]

Wow! I'm pretty sure I found an old video camera just like that in a thrift store.

[bmarshall-2]

100k pot for the gain adjust on your LM386, are you sure?! do you mean 1k?

[kikazz]

I apologize for my rudeness... I should have been a little more thoughtful with my remarks. and hey, im starting to spell bad too. Sorry.

[AdamMunich]

No problem, I used to use IE back then. IE had and still does not have a spellcheck.

[kikazz]

pleeeeeeeeeeease learn to spell. it really is annoying. thanks

[El Mano]

Forgive me, but part of spelling is capitalization. Good job with the punctuation, though.

It's so funny when people post indecipherable garbage. It really reflects their personality.

[12V]

i took apart a camcorder and found a crt with a 16mm screen and 6 pin base + a psu (2,200v) as well.
for brightness try adjusting the trimpots
e.g. those blue things with a screwdriver.

[12V]

try putting a 4.7-10 uf cap on the output of regulator  (mightprevent/reduce picture shrinkage)

[luudvig]

Awesome!!

[uskmrules]

 hey can u take a picture of the board where ur power wires and video wires connect to the tv board. i cant find the wires.

[dark sponge]

Why are you using two 9v batteries? You could just use one. Better yet, use an old 9v wall adapter.

_{(by the way, I'm 13 too!)}

[AdamMunich]

(removed by author or community request)

[dark sponge]

You could use 6 rechargeable AA batteries. It would last longer and would supply enough power for the sound and the picture at the same time.

[AdamMunich]

No; I have used a car battery and the same thing has happened.

[ReCreate]

Then the problem is not lack of power....

[12V]

can't you use a separate voltage regulator for each circuit. and a will charged battery.

[dark sponge]

That's weird...

[AdamMunich]

(removed by author or community request)

[dark sponge]

But that shouldn't happen if you use a bigger battery.

[AdamMunich]

well id does for some reason.

[The 4th Doctor]

I believe its because when the audio circuit is drawing power it steals voltage from the video circuit making it so although the powersource can supply the amperage the tv circuit isent getting the voltage to do so. ohms law ftw!

[dark sponge]

But that shouln't have happened when he used a car battery. Something else must be going on because it would have to draw tens (or even hundreds) of amps for this to happen with a car battery (which he said he tried).

[The 4th Doctor]

Its the voltage the battery is capable of supplying the current but its voltage is divided up upon the 2 circuits spreading it thin it is kind of odd though that the video circuit has trouble when its rated for 5 volts maybe its just how much audio fluctuates

[dark sponge]

The amount of current a battery can supply is not based on it's voltage, but it's internal resistance. Bigger batteries (like car batteries) have a lower internal resistance, so they can supply a greater amount of current.

[The 4th Doctor]

The maximum current is limited by internal resistance yes but the voltage/resistance determines how much current Does flow in a given situation every battery max's out somewhere but the current it supply's to a given situation is changed by its voltage and the loads resistance Anyways audio fluctuates CRT's seem to get affected from pretty small changes, my TV flashes a bit when i turn stuff on/off i suppose the video circuit probably doesn't even have a filter capacitor I shall leave it at that

[AdamMunich]

It seems to go away when i use a switching power adapter. Not a transformer adapter though.

[12V]

it's because they use voltage regulators.

[okura]

Unbelievable.....a KID of 13yrs has SO much electronic savvy, so much vocabulary, so many tricks???? ...have seen many child prodigies and have mentored some myself, but this guy beats them all !! Either he's a miracle or a well planned hoax. Wish it isn't the later though...... I wish him good luck and Gods very best!!!! PS: wish there are ( I'm sure there are ) more kids like him around, too!

[dannydutton]

Oh, now i understand the schematic now. I couldn't figure out what 7805 was then I remembered the regulator (5V right?). Is there a way for you to tell what the ground and positive lines are on video cable? Where can the ground go to, the battery?

[AdamMunich]

yes grnd> -bat ground on vid cable is usually the 'hairy wire'

[Aleksaa]

seriously now that it really works or not, and is used as osciloscope?

[Aleksaa]

just as in the picture, and who I make it just the same as in the picture and work? my viewfinder has only 4 pin.2 are the power and other 2 I do not know

[AdamMunich]

yes it should. so you found the power? good. thats tha hard part. one of those other two is video signal in. Cut a composite (yello) video cable in half and strip the wires. Attatch the shield (outer wire) to negative on the tv and power it up. plug the video cable into your xbox or something. now, try touching the center wire of the video cable to one of the two unknown wires. whichever one works is your video in.

[aleksa]

i done that and shows static.The viewfinder is from an old vcr blakpount cam....:(

[AdamMunich]

OK, the one that shows static is video in. you need to make sure it is securely connected to get a picture, like soldered. then if it is still staticy, look for potentiometers on the circuit. they look like plastic screws. turn them while the TV is on. if you keep fiddling with them, eventually you should fin the sweet spot and get a picture. one is brightness, one is focus, and one is v-hold. there may be more. even better. is the video signal you are trying to put in NTSC? PAL or SECAM will not work.

[aleksa]

you are only 13 and you are a GENIUS...its working...!!!

[razieltehawesome]

how would you make this just a tv and no oscilloscope?

[aleksa]

i done that it shows just static.....damn : (

[razieltehawesome]

what are the details on the 10uf capacitor?What kind of Relay? where can I get the 2m potentiometer meter?

[AdamMunich]

(removed by author or community request)