tube intercom

[lee]

Hi everyone,

I took this intercom out of an apartment that I used to live in. I've had it for a few years thinking, "One day I'm going to get this thing to work and it's going to be sweet." But still, I don't have a clue how to start working on this thing, or if it is even worth the effort. Check it out, I put a ring next to it to show the size. It has tubes amplifiers, and a built-in speaker! The problem is, the electronics are pretty old fashioned, so I don't think that I can go to a hardware store and get parts.

If anyone could let me know if this is worth keeping, and if so, how to fix it.






Thanks.

[sound for sandwiches]

hard to tell from the pics, but it looks like the switch in the center decides whether the speaker makes sound or acts as a microphone. if you got it running you could maybe use it for special effects type vocals.

Also looks like you have a transformerless power supply and "death cap" situation. if you have no clue about working on these kinds of circuits I would either have someone who knows what they're doing determine its functionality and safety, or else put it on the mantlepiece as a curiosity.

parts are easy online. tubesandmore.com for one, there are many others as well.

David

[CedarSound]

Not to hijack,

But, I bought a very similar thing this past summer from a really inebriated old dude at a Flea Market. It's a tube radio/intercom from an old department store. It has the same exact type of plug that yours has...
Any idea where I can find a power plug that will fit that kind of jack? I have a two pronger, but it doesn't fit for some reason.

[bluesman]

Antique Electronics Supply

[lee]

It's cool Cedarsound, I was wondering the same thing. But like Sandwiches said, be careful about plugging these things into the wall. I might be wrong, but I think that they store power in one of the electronic components, and if you touch it, it might kill you. For real.

CedarSound, do you have any advice on where I could take this to have it worked on? If not a specific place, what kind of business would take care of something like this? Also, I am a student; do you think that an electronics lab might have the things that I would need to fix this?

[The Scum]

If you want to take it back to original spec as an intercom, the first thing you need is a schematic. I see an empty tube socket, and it's anyone's guess what goes there...who knows what else has been lost or removed?

You could always gut it and build a gresh guitar amp with the chassis & maybe the speaker.

I might be wrong, but I think that they store power in one of the electronic components, and if you touch it, it might kill you. For real.

And that's absolutely true.

It's the cylindrical component that's kinda in the middle of the "sandwhich" formed by the chassis, peeking through the large round hole in the back.

If you want to start learning about tube amps, there are plenty of web sites...I'd start with one that addresses some of the safety issues involved.

[Snarl 12/8]

Again, not to hijack...

But just looking at that thing really reminds me of my Heathkit signal tracer guitar amp...
http://messageboard.tapeop.com/viewtopi ... nal+tracer

If you can find one (I totally lucked out at a local computer thrift store) it might be an easier and more satisfying audio project for you.

http://cgi.ebay.com/HEATHKIT-IT-12-SIGN ... 439c944750

[sound for sandwiches]

If you want to take it back to original spec as an intercom, the first thing you need is a schematic. I see an empty tube socket, and it's anyone's guess what goes there...who knows what else has been lost or removed?

I was looking at that, and judging from how many wires are going to it, I would say that octal socket wasn't used for a tube. I'm thinking accessory mic or headset or something.

If I were to adapt that circuit for a guitar amp, I would not bother with the built in speaker, it's probably all of 4" in diameter? I bet the power tube pushes a watt or so at most, which is enough to get sound out of a bigger guitar cab, and will probably sound better doing so.

That said, I still think that circuit has no power transformer, so it will take a lot more than just slapping an output jack and power cable on there to make it safe and useable. are the tube types readable? that will help figure out how the circuit is set up.

[aurelialuz]

i have a coupe of these that i have been playing with, not these brand exactly, but these are all similar. i've decided just to gut it, for a little one input tube, one output tube, one rectifier type circuit, but the power supply transformer is the biggest question. i wouldn't be able to jam one into the case (and really wouldn't want to, since the shielding would be...a challenge) so an outboard is an order. maybe the empty tube socket in yours was a power supply connection, as i've seen a lot of machines of this vintage that use that same octal connection for it's transformer or power section.

i have the accompanying speaker box too, and made into a little "cabinette." it sounded like shit. these speakers don't really take low frequencies very well.

[lee]

Even if it does sound like shit, I was thinking that it would make for a cool texture, an effect.

But it sounds like this is going to be out of my league. I have never done any sort of electronic modifications, what-so-ever. I was hoping someone would tell me, "Yeah, it's really easy; just turn it on!"

If anyone is interested in having this, give me postage and I'll send it your way.

[sound for sandwiches]

I'm thinking of taking you up, if just for the knobs. they're cool looking!

[aurelialuz]

Even if it does sound like shit, I was thinking that it would make for a cool texture, an effect.

i thought the same thing, but the sound is a farty 'speaker beyond it's capacity' kind of thing, not a Kinks 'razor the speakers' kind of thing. but you could always just wire the speaker straight to a jack. my speaker measured out at 4 ohm, you might want to put a 4 ohm in series.

[Scodiddly]

May be a hot (voltage) chassis, which is not promising. You can tell by looking at the tube numbers on the existing tubes - if they start with higher numbers than the usual 6 or 12, then it's a hot chassis with no power transformer.

That square thing made of stacked plates usually has toxic innards.

Maybe writing your own schematic would be a good thing to try - you'll learn a lot in the process.

[lee]

Everything electronic that I touch turns to powder in my hands. I like to think that I am somewhat handy, and possess an intuitive knack when it comes to gizmos, but when it comes to working with electronics, everything always goes to hell. And now you tell me that this thing could deliver a death current! This would be the end of me if I started plugging it in and poking aimlessly around. Electronics, your song is meant for another.

Send me a message and this cool little project is all yours!