Sterdy 3 wire intercom wiring - UK Vintage Radio Repair and Restoration Discussion Forum

Scottysnap62 · 15th Nov 2016, 8:47 pm

Hello

I need to ask for some advice please. I have a couple of old black metal Sterdy 3 wire single station intercoms, I have enclosed a couple of pictures one of which I have traced out a wiring diagram.
I need some advice as to wire them both together, ie battery etc.
Thank you in advance

Scott

AC/HL · 16th Nov 2016, 12:18 am

We had a previous thread, which may help: https://www.vintage-radio.net/forum/...d.php?t=102457

TonyDuell · 16th Nov 2016, 6:49 am

My first guess (not knowing anything about these units really...) would be to interconnect terminal 1 (your naming) between the units, ditto for terminal 3. Connect a battery between 2 and 3 at each unit, but the opposite way round. In other words, positive to terminal 2 at one unit, positive to terminal 3 at the other.

Start with 1.5V, go up in 1.5V steps until the buzzers work well, my guess is that it's either 3V or 4.5. The 2 batteries should be the same.

Dave Moll · 16th Nov 2016, 9:03 am

I have three of these slave units connected to a master that can interconnect up to seven slaves. It works well with a singlr 6V battery connected to the master, but I think it will happily work on less. I haven't tried connecting the slaves together without use of the master, though.

I think I've documented the wiring of my system somewhere, which might be adaptable to using a pair of slaves as a stand-alone system. If I can find it, I'll post it here.

dagskarlsen · 16th Nov 2016, 1:55 pm

Something like this?

TonyDuell · 16th Nov 2016, 5:45 pm

Yes, that's what I had in mind. For speech both handsets are in series across the total battery (2 batteries in series). For calling, one battery operates a buzzer when the switch is pressed.

It may not be the original way of wiring them, but it may well work for 2 stations.

Scottysnap62 · 17th Nov 2016, 12:39 am

All

Many thanks indeed for all your help. I will work on this this weekend, I will be using either a single lantern 6volt battery in the middle of the two units or use 3 D cells at each station utilising a 4.5V supply.

Scott

15th Nov 2016, 8:47 pm	#1
Scottysnap62 Retired Dormant Member Join Date: Jul 2013 Location: Pulborough, West Sussex UK. Posts: 10	Sterdy 3 wire intercom wiring Hello I need to ask for some advice please. I have a couple of old black metal Sterdy 3 wire single station intercoms, I have enclosed a couple of pictures one of which I have traced out a wiring diagram. I need some advice as to wire them both together, ie battery etc. Thank you in advance Scott Attached Thumbnails

16th Nov 2016, 12:18 am	#2
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: Sterdy 3 wire intercom wiring We had a previous thread, which may help: https://www.vintage-radio.net/forum/...d.php?t=102457

16th Nov 2016, 6:49 am	#3
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,222	Re: Sterdy 3 wire intercom wiring My first guess (not knowing anything about these units really...) would be to interconnect terminal 1 (your naming) between the units, ditto for terminal 3. Connect a battery between 2 and 3 at each unit, but the opposite way round. In other words, positive to terminal 2 at one unit, positive to terminal 3 at the other. Start with 1.5V, go up in 1.5V steps until the buzzers work well, my guess is that it's either 3V or 4.5. The 2 batteries should be the same.

16th Nov 2016, 9:03 am	#4
Dave Moll Dekatron Join Date: Feb 2005 Location: West Cumbria (CA13), UK Posts: 6,130	Re: Sterdy 3 wire intercom wiring I have three of these slave units connected to a master that can interconnect up to seven slaves. It works well with a singlr 6V battery connected to the master, but I think it will happily work on less. I haven't tried connecting the slaves together without use of the master, though. I think I've documented the wiring of my system somewhere, which might be adaptable to using a pair of slaves as a stand-alone system. If I can find it, I'll post it here. __________________ Mending is better than Ending (cf Brave New World by Aldous Huxley)

16th Nov 2016, 1:55 pm	#5
dagskarlsen Heptode Join Date: Jan 2008 Location: Hakadal, Norway Posts: 643	Re: Sterdy 3 wire intercom wiring Something like this? Attached Thumbnails

16th Nov 2016, 5:45 pm	#6
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,222	Re: Sterdy 3 wire intercom wiring Yes, that's what I had in mind. For speech both handsets are in series across the total battery (2 batteries in series). For calling, one battery operates a buzzer when the switch is pressed. It may not be the original way of wiring them, but it may well work for 2 stations.

17th Nov 2016, 12:39 am	#7
Scottysnap62 Retired Dormant Member Join Date: Jul 2013 Location: Pulborough, West Sussex UK. Posts: 10	Re: Sterdy 3 wire intercom wiring All Many thanks indeed for all your help. I will work on this this weekend, I will be using either a single lantern 6volt battery in the middle of the two units or use 3 D cells at each station utilising a 4.5V supply. Scott