Need recommendations for a wired intercom system.

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Aerindel

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I would like to set up a intercom/interphone pair between my house and my parents house, about 500 feet away so that my five year old has a phone she can use between the two housholds and so that we have a secure way of talking off grid. I just got this set:


But it was junk, only one phone worked and both where badly made.

Any suggestion for something better that isn't as expensive as vintage military field phones?
 
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I would like to set up a intercom/interphone pair between my house and my parents house, about 500 feet away so that my five year old has a phone she can use between the two housholds and so that we have a secure way of talking off grid. I just got this set:


But it was junk, only one phone worked and both where badly made.

Any suggestion for something better that isn't as expensive as vintage military field phones?
You already ran 500' of wire from house A to house B?
Above ground or in ground?
Wasn't that expensive?
 
Nope, didn't get that far. Just testing the phones I found one was defective brand new.

But the cost of 500 feet of direct burial phone wire is only about $50.
 
would walkie talkie work?

I'd rather have something simpler. I have half a dozen FRS capable radio's but trying to keep one always on at my folks house and teaching my kid to use one is probably destined for failure. Really just hoping to set a 'hot line'.
 
would walkie talkie work?
I think he wants secure wired communication that can ring a bell in house A or B.
No dial, just pick it up when it rings and talk. Like we had in 1962 😉.
 
You could put your own phone system like a Norstar. You will also want to make sure and ground both ends of that cable and use lightning protectors on it.
 
Secure, off-grid: Have you considered a pair of MURS radios with voice inversion scrambling?

e.g., Motorola RMM2050 MURS Two Way Radio

The above radios are 2 watts in the VHF range, so you're not going to be blasting your signal far for many people to be able to receive it. The 500 feet you need should not be a problem, unless you are going from inside a metal shielded building to the inside of another metal shielded building with a bunch of other obstacles in the way.

MURS does not require an FCC license. And voice inversion scrambling is probably good enough, unless you're into some super secret spy stuff. Radios would be mobile too, unlike intercoms.

inversion.jpg


Encryption Basics
 
Advice on how to set that up would be great.
Not that quick. Maybe an Aiphone system. Are you looking for a phone type intercom or a wall mount speaker type.

An intercom like they use on boats would do well I think.
 
But the cost of 500 feet of direct burial phone wire is only about $50.
Realize that just because you can buy a 500 foot spool of cable does not mean that you can use a 500 foot length of it - it's meant to be cut into smaller chunks and used that way. And if that 500 feet only cost you $50 and it's direct burial rated, it is going to be thin (probably 24 maybe even 26 gauge), cheap, lossy cable. I can't believe you found a direct burial cable so cheap. Anyway, you may not have enough signal left after traveling that far to be useful for anything. It possibly will have been attenuated all the way down into the background noise level.
 
Any suggestion for something better that isn't as expensive as vintage military field phones?

How much work do you want to do?

I was in the payphone industry for about 15 years before they became dinosaurs, but phones and lines are very easy to do.

Two corded phones and a power source, either a 9V battery or a small power source that you can plug in.

Landline phones only require a very small electrical source to operate which is generated from the phone company. So.........for an independent system you will need to provide said power.



The only issue is, it won't ring without a tone generator, but, you can wire in a small LED light that comes on when someone picks up one of the phones. The problems with that is unless you notice the light come on it's still a bit user unfriendly.

But, you can set it up with your own tone generator.




You could build 2 of these setups, mount them to a board and place the board wherever you want at each location, plug them in and talk away.
 
One more thought/addition to my above post.

If you can find 2 older phones that actually have the ringer bells in them, you might be able to power and activate them from another 'pair' in the cable you use and you wouldn't need the tone generator.

Phone voice on red/green and power to ring the bells on the black/yellow pair. You would just need to have a power source and a button to push on each end to activate the bells. It would probably ring on both ends when doing that, but that wouldn't be a big deal.
 
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@Curmudgeon I installed Nortel PBXs for over 20 years.

The problem is those phones need about 90v DC ring voltage and it uses the same pair of wires. Red/Green or White/Blue

I have never run into an analog phone that uses the black/yellow pair to power the ringer.
 
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I have never run into an analog phone that uses the black/yellow pair to power the ringer.

In this case he can use any combination of pairs as it isn't tied into the phone system.

Only reason I suggest it is because it would keep the ringer and voice part separate. Then again, it may very well work on one pair, as it does from the LEC.
 
If you use CAT-5 wire, you'll have 4 pair (8 wires total). A 500' roll is about $60.
When I buried wire, I found the most simple and cleanest tool for burying it was a lawn edger. I ran the edger and the Mrs. followed behind with a 1' wooden ruler to push the cable into the ground.
 
FWIW, here is a link to a Youtube video that shows you what "voice inversion scrambling" sounds like (the first ten seconds of the video demo the audio, the rest of the video can be skipped):



I know the O.P. is not interested in this technology, but there might be others reading this thread who are.
 
It is relatively easy to use two phones as an intercom. You use a 12 volt "Son-a-lert" to replace the ringer.
I have done this before and I have the diagram someplace. I used a 12 volt supply and it worked great.
If anyone is interested I will post the diagram and material list.
 
@Curmudgeon I installed Nortel PBXs for over 20 years.

The problem is those phones need about 90v DC ring voltage and it uses the same pair of wires. Red/Green or White/Blue

I have never run into an analog phone that uses the black/yellow pair to power the ringer.
You touched on an often overlooked part of this.
If the signal is to go over 500', if it is digital the wire will have to be twisted-pair. If the signal is analog, it can go over a straight pair, but you will need 24v-90v DC to make it work.
The OP said he didn't want to use antique hardware.
Since the entire world went wireless, this is more difficult than it appears, to do today.
 
You touched on an often overlooked part of this.
If the signal is to go over 500', if it is digital the wire will have to be twisted-pair. If the signal is analog, it can go over a straight pair, but you will need 24v-90v DC to make it work.
The OP said he didn't want to use antique hardware.
Since the entire world went wireless, this is more difficult than it appears, to do today.

I have no problem with antique hardware, prefer it in fact, what I want to avoid is spending $500 on a pair of military field phones. While perfect for what I need, they are expensive collectors items now.
 
If the signal is analog, it can go over a straight pair, but you will need 24v-90v DC to make it work.

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

You use a 12 volt "Son-alert" to replace the ringer.

Looks like more than one way to skin a cat here.
 
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