UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Telephony and Telecomms

Notices

Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment

Reply
 
Thread Tools
Old 15th May 2020, 10:37 am   #1
Sparks
Hexode
 
Join Date: Oct 2006
Location: Leeds, West Yorkshire, UK.
Posts: 329
Default Tandy/Realistic FM wireless intercoms

Does anyone have any experience of these devices, whether good, bad or indifferent ? I remember seeing them in the Tandy catalogues for years in the 1980s with the seemingly bold claim that all you had to do was plug in to the mains, switch on and you were in business, so to speak. If I've got it right, the technology was something like an FM transmission superimposed on the mains cabling, however that worked. I particularly remember that it was possible to use the sets not only within your own house or office, but also with your next door neighbour, provided there was some degree of electricity supply commonality.

I've neither seen nor used any such device and I don't know if the likes of Eagle and Sterdy make them. Obviously, Tandy disappeared years ago.

Many thanks.
Sparks is offline   Reply With Quote
Old 15th May 2020, 11:06 am   #2
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 4,234
Default Re: Tandy/Realistic FM wireless intercoms

Yes, we had some Tandy ones for a while. There are so many other signals superimposed on the mains now - powerline networking adaptors, etc - that I'm not sure such simple 'analogue' devices would be able to function any more.

They did depend on both, or all stations, being on the same mains phase.
SiriusHardware is offline   Reply With Quote
Old 15th May 2020, 11:31 am   #3
Sparks
Hexode
 
Join Date: Oct 2006
Location: Leeds, West Yorkshire, UK.
Posts: 329
Default Re: Tandy/Realistic FM wireless intercoms

Thankyou Sirius. I thought I remembered something about being on the same mains phase.
Sparks is offline   Reply With Quote
Old 15th May 2020, 8:07 pm   #4
hamid_1
Hexode
 
Join Date: Aug 2009
Location: High Wycombe, Bucks. UK.
Posts: 489
Default Re: Tandy/Realistic FM wireless intercoms

I have an Altai branded one, probably much the same internally as the Tandy ones. It uses low frequency RF transmission. I think mine can be switched to 150KHz or 250KHz to avoid interference or conflict with your neighbours. Both of these frequencies are in the long-wave band. I can pick up the intercom on a normal domestic LW radio in the same room, even though ithe radio is AM and the intercom is supposed to be FM.

Other than the above reception test, I haven't actually used it as an intercom, since I only have the one base unit. A pair is required. I'm guessing that these intercoms should still work despite much more mains-borne noise these days. FM is supposed to be quite good at rejecting interference.
hamid_1 is offline   Reply With Quote
Old 15th May 2020, 8:40 pm   #5
OscarFoxtrot
Heptode
 
OscarFoxtrot's Avatar
 
Join Date: Apr 2011
Location: Edinburgh, UK.
Posts: 750
Default Re: Tandy/Realistic FM wireless intercoms

I had one. They didn't like ring circuits (distorted sound to the point of uselessness) but would work fine on an extension lead.

That was in the days of rewireable fuses. With MCBs and RCDs in circuits there might be more obstruction to the signal.

As well as the speaker versions there were one or two handset-style ones available.
OscarFoxtrot is offline   Reply With Quote
Old 15th May 2020, 9:12 pm   #6
Sparks
Hexode
 
Join Date: Oct 2006
Location: Leeds, West Yorkshire, UK.
Posts: 329
Default Re: Tandy/Realistic FM wireless intercoms

It was probably quite a good idea, at least initially, to use the mains wiring for something other than moving electricity around and at no added cost. Not unlike the early American telephone networks that used the barbed wire fences around the farms and ranches as transmission cables. Certainly not ideal but better than nothing.
Sparks is offline   Reply With Quote
Old 15th May 2020, 11:03 pm   #7
Julesomega
Heptode
 
Julesomega's Avatar
 
Join Date: Dec 2012
Location: Stockport, Greater Manchester, UK.
Posts: 689
Default Re: Tandy/Realistic FM wireless intercoms

I believe that electricity consumer meters are or were opaque at around 150kHz. This means you are isolated from your neighbour's mains intercom
__________________
- Julian

It's good here
Julesomega is offline   Reply With Quote
Old 16th May 2020, 12:56 am   #8
Terry_VK5TM
Octode
 
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 1,326
Default Re: Tandy/Realistic FM wireless intercoms

I've still got 2 pair of them and used them from house to shed until a few years ago.

They had to be used on the same phase and wouldn't work across different phases of a three phase system so it was possible to work the house next door, depending on which phase they were connected to.

Modern equipment, with filters, plugged in around the house does diminish their usefulness to the point of being unusable now.

And yes, they superimposed the audio onto a carrier that was superimposed on the mains.

There were circuits in some of the older mags like Practical Electronics from memory where you could build your own.
__________________
Terry VK5TM
https://www.vk5tm.com/
Terry_VK5TM is offline   Reply With Quote
Old 16th May 2020, 8:03 am   #9
Sparks
Hexode
 
Join Date: Oct 2006
Location: Leeds, West Yorkshire, UK.
Posts: 329
Default Re: Tandy/Realistic FM wireless intercoms

It would be a nuisance if you'd bought a set for something other than in-house communication to find that your individual electricity supplies weren't on the same phase.
Sparks is offline   Reply With Quote
Old 16th May 2020, 8:18 am   #10
60 oldjohn
Nonode
 
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 2,681
Default Re: Tandy/Realistic FM wireless intercoms

Quote:
Originally Posted by Terry_VK5TM View Post

There were circuits in some of the older mags like Practical Electronics from memory where you could build your own.
I expect it will be a similar idea to my Pye PTC1001 from 1950s/60s. but using semiconductors, not valves.

John.
__________________
My favourite text message "I'll be there in five minutes, if not read again"
60 oldjohn is offline   Reply With Quote
Old 16th May 2020, 9:30 pm   #11
AndiiT
Octode
 
AndiiT's Avatar
 
Join Date: Aug 2005
Location: Saltburn-East, Cleveland, UK.
Posts: 1,660
Default Re: Tandy/Realistic FM wireless intercoms

Hi, there is currently a pair of the Tandy/Realistic units that you mention listed on eBay here

I have no association with the seller and have included the link for the purpose of interest only.

Andrew
AndiiT is offline   Reply With Quote
Old 16th May 2020, 9:37 pm   #12
Sparks
Hexode
 
Join Date: Oct 2006
Location: Leeds, West Yorkshire, UK.
Posts: 329
Default Re: Tandy/Realistic FM wireless intercoms

Thanks for the heads up Andi. At that price I believe I'll pass but it would be interesting to see how well they perform these days.
Sparks is offline   Reply With Quote
Old 22nd May 2020, 10:50 pm   #13
OscarFoxtrot
Heptode
 
OscarFoxtrot's Avatar
 
Join Date: Apr 2011
Location: Edinburgh, UK.
Posts: 750
Default Re: Tandy/Realistic FM wireless intercoms

With the same Ebay disclaimer, a pair of the handset style here. Circuit diagram is included - typically for Tandy stuff it will be the USA version in the manual.
Attached Thumbnails
Click image for larger version

Name:	plugntalk.jpg
Views:	51
Size:	47.3 KB
ID:	206488   Click image for larger version

Name:	plugntalkcct.jpg
Views:	56
Size:	38.8 KB
ID:	206489  
OscarFoxtrot is offline   Reply With Quote
Old 23rd May 2020, 10:11 pm   #14
buggies
Hexode
 
buggies's Avatar
 
Join Date: Jan 2009
Location: West Lothian, UK.
Posts: 447
Default Re: Tandy/Realistic FM wireless intercoms

I sold mine two years ago for 9.99.
They worked ok in my house and on 25 metre extension to garden shed but we don't have any powerline digital stuff.
The buyer initially claimed they were non-functional although did not return them for testing.
Attached Thumbnails
Click image for larger version

Name:	tandy2.jpg
Views:	31
Size:	74.7 KB
ID:	206590   Click image for larger version

Name:	tandy1.jpg
Views:	22
Size:	52.9 KB
ID:	206591   Click image for larger version

Name:	tandy3.jpg
Views:	24
Size:	72.5 KB
ID:	206592  
__________________
George
buggies is offline   Reply With Quote
Old 25th May 2020, 3:17 pm   #15
ljones0
Tetrode
 
Join Date: Feb 2007
Location: Fordingbridge, Hampshire, UK.
Posts: 56
Default Re: Tandy/Realistic FM wireless intercoms

Have an old device here as well and strangley it can be received in the long wave band as well(!) - although the radio has to be pretty much next to the device or nothing is received. The device is branded as a national VK233 and I think maybe from the 80s. Unfortunatly mine do not seem to be working all that well - the range is so bad it only works from within the same room (I do have a second device); try plugging in one upstairs and one downstairs and nothing - !

Does anyone know why it should be quite *that* bad? I mean I wouldn't expect mircacles from such an old device, but not doing anything from upstairs to downstairs seems to indicate some sort of fault to me.

ljones
Attached Thumbnails
Click image for larger version

Name:	0.jpg
Views:	25
Size:	105.7 KB
ID:	206754  

Last edited by ljones0; 25th May 2020 at 3:23 pm.
ljones0 is offline   Reply With Quote
Old 25th May 2020, 5:56 pm   #16
OscarFoxtrot
Heptode
 
OscarFoxtrot's Avatar
 
Join Date: Apr 2011
Location: Edinburgh, UK.
Posts: 750
Default Re: Tandy/Realistic FM wireless intercoms

A combination of ring circuits, and MCBs/RCDs in modern consumer units, blocks the signal.

Try fitting the devices to lighting circuits which are radials and might not be on RCDs.
OscarFoxtrot is offline   Reply With Quote
Old 25th May 2020, 8:43 pm   #17
Sparks
Hexode
 
Join Date: Oct 2006
Location: Leeds, West Yorkshire, UK.
Posts: 329
Default Re: Tandy/Realistic FM wireless intercoms

It seems as though modern domestic electrical wiring has left behind the FM wireless intercom.
Sparks is offline   Reply With Quote
Old 25th May 2020, 8:55 pm   #18
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 8,634
Default Re: Tandy/Realistic FM wireless intercoms

Quote:
Originally Posted by Sparks View Post
It seems as though modern domestic electrical wiring has left behind the FM wireless intercom.
Yes - here in the UK they once sort-of worked OK on ring-mains. But I remember that even back in the 1970s they were 'marginal' on the standard US one-15A-radial-per-room power-wiring.
G6Tanuki is offline   Reply With Quote
Old 29th May 2020, 12:32 am   #19
Herald1360
Dekatron
 
Herald1360's Avatar
 
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 14,521
Default Re: Tandy/Realistic FM wireless intercoms

Quote:
Originally Posted by OscarFoxtrot View Post
With the same Ebay disclaimer, a pair of the handset style here. Circuit diagram is included - typically for Tandy stuff it will be the USA version in the manual.
I bought these to play with

Anyway, here's a hopefully legible copy of that circuit for interest.

Inverters are 4069, audio amp is LM386 and IC3 is LM567.
Attached Thumbnails
Click image for larger version

Name:	Tandy2.jpg
Views:	26
Size:	100.1 KB
ID:	207089  
__________________
....__________
....|____||__|__\_____
.=.| _---\__|__|_---_|.
.........O..Chris....O
Herald1360 is offline   Reply With Quote
Old 29th May 2020, 8:10 am   #20
OscarFoxtrot
Heptode
 
OscarFoxtrot's Avatar
 
Join Date: Apr 2011
Location: Edinburgh, UK.
Posts: 750
Default Re: Tandy/Realistic FM wireless intercoms

This is a mains programme distribution unit, from Public Address Handbook, Vivian Capel. Separate sender and receiver.

A two-stage modulator which modulates the collector current of the rf oscillator. Should be at about 100 kHz. There is no frequency stabilising. Applies the output to live and earth (not neutral) as this avoids the effect of heavy shunting loads in the circuit. (This dates from 1971 when RCDs were either unknown or certainly not in common use.)

A tuned circuit and diode detector in the receiver.

"All components are standard except the oscillator coils which were specially wound."
Attached Thumbnails
Click image for larger version

Name:	mainssender.jpg
Views:	18
Size:	60.1 KB
ID:	207096   Click image for larger version

Name:	mainsreceiver.jpg
Views:	17
Size:	122.4 KB
ID:	207097  
OscarFoxtrot is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 4:31 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Copyright ©2002 - 2020, Paul Stenning.