wiring two old intercom telephones

[g4ztfa]

Hi all

I would like some help wiring two old intercom telephones together.
Power goes into only one of the phones as a 6v mains adaptor supply or 4 x AA batteries. The 2 phones then connect by an unknown amp, 2 core cable.

Basically I am wanting to know how far apart these phones could be and what cable I should use to connect them. Ideally I want them 20-30 metres apart, can I boost the power supply? if so how?

Thanks for any advice.

Gaz

 

[feselectrical]

I could be wrong here but ill try to help...I think that you wont be boosting the power supply as such you will just use two pairs from say a 6 or 8 core cable..if you twist the two together before terminating this should account for any voltage drop...

but like i said, ive been wrong before...once, in 1997.

 

[BlueToBits]

Inteference and capacitive effect is probably more of an issue than volt drop. The current is likely to be really low - only a few milliamps, so the volt drop shouldn't be much to speak of over 30 metres of cable. It isn't that far for an intercom anyhow. Run it in temporary using bell wire and give it a go. Even better, use professional twisted pair microphone cable and earth one end of the screen.

I was once wrong in 1986 but one of us is going to have to add 2010 to our claim ;-)

 

[nickblake]

you dont need to boost your power supply ,on intercoms you need a good quality cable between them ,and to avoid noise etc all intercoms i have installed i have and is recommended that you use a twisted pair telephone cable , but these days i use CAT5E ,works a treat