Need recommendations for a wired intercom system.

[Haertig]

Yes. I believe it's 90v to ring the old bell ringers phones.

That is correct. In the USA, ringing voltage is 90vac for sure, and I believe it's 60Hz. I know for sure that in Bonn , Germany the ringing voltage is (or was) 60vac, 50Hz. That's because the first design project I had out of college with my new shiny EE degree was to design and build a "central office simulator" for the US embassy in Bonn to test our special development phone hardware (I was working for AT&T/WesternElectric). I remember the Bonn details because I had to design and built all that from scratch. The USA stuff, I was able to buy the ring generator rather than design it, so while I remember the voltage, I have forgotten the frequency, but I'm pretty sure it was 60Hz. Tip/Ring voltage is 48vdc - that's what powers you phone for voice transmission.

You can grab the two primary phone wires and not feel the 48vdc. However, if the phone rings while you are holding them, THAT will catch your attention! Even my lower voltage Bonn simulator caught my attention a time or two.

 

[Cnsper]

Doesn't hurt but you need to check your shorts... lol

 

[The Lazy L]

How about a small business phone system like a Panasonic TA308? Put the system and one extension phone in your house and another extension phone in the other location. Would operate like standard phones.

24 gauge wire is what our local Telephone Company uses for thier main cables and the drops to the houses/businesses.

 

[Supervisor42]

Doesn't hurt but you need to check your shorts... lol

I seen what ya' did right there.
'Shorts', electrical pun .

 

[Neb]

Yeah, and it is AC when it rings the (your) bell not DC.
Been there, almost pee'd my pants

Add me to that list.

Old joke- supposedly a true story...

A Bell telephone worker responded to a call to fix a problem where the phone was not ringing.

Customer: My phone doesn't ring when I get a phone call but works OK otherwise.

Tech: If it does not ring how do you are getting a call?

Cust: My dog barks when I get a call.

Tech: ????

Investigation showed that the customer had used the ground rod for the dogs chain. After time the effect of the dog urinating on the ground rod, the corrosion had induced a bad ground path... Except through the dog.

That is my story and I am going to stick with it.

Ben

 

[UrbanHunter]

I saw the $50 wired intercom phones on Amazon, they come with 3' of line and can run on AC or batteries. They say they can be used for up to 200 meters, but the reviews also say that the volume is low...

Looked at a couple of articles that used old phones some resistors, capicitors, diodes, and a busser with a 9V battery, they indicated that they could work up to a mile if you increased the voltage a little.... If you could find a couple of old phones and a breadboard it would be worth experimenting with.. I know I threw out a box of those things a year ago.

You can buy the old wired phones new for about $15 on amazon, so for about $75 you should be able to get 2 phones, the parts, and enough Cat-5 wire to do the job.

 

[Cnsper]

You don't need CAT5 wiring. You can run an analog signal on 2 strands barbed wire if it was not grounded. The direct burial cable discussed will do just fine.

Like I said you need to protect both ends. Most lightning protection only protects people. You want oneac protectors. These are used on split 66 type blocks. The black ones are for analog circuits and the yellow are for digital circuits. The screw is used to attach to a ground bar. Believe me when I say, I would never have a cable buried without protection.

These oneac protectors are designed to protect equipment so they clamp down much faster than the standard protectors. I have seen hundreds of thousands of dollars damage caused by lightning strikes and after I was done they never had that kind of damage again.

There are plenty of cheap phone systems but your $500 limit is too low. Keep an eye out on craigslist though and you may get lucky.