View Single Post
Old 27th Jul 2019, 9:37 am   #5
TonyDuell
Dekatron
 
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,190
Default Re: Vintage Arrow ( Toy? ) Telephones

Quote:
Originally Posted by Herald1360 View Post
Possibly simply lifting the handset on the calling phone activates the buzzer in the called one. Lifting the called one completes the speech loop and silences its buzzer.
The problem with that is that you need the microphone/earpiece in series with the loop at the calling telephone when you are speaking but they have rather too high a DC resistance to be in-circuit when sounding the buzzer. I seem to remember that in some (most?) of these telephones the calling switch just shorts out the microphone/earpiece and puts the battery to the interconnecting cable.


Quote:
Originally Posted by Herald1360 View Post
The speech circuit is probably a simple series connection of all microphones earpieces and batteries. Should be easy enough to reverse engineer if enthusiastic.
All the ones I've seen have a 2-wire handset cable and the microphone/earpiece are in series in the handset.

Normally the 2 telephones in the set are indentical, but the line wire is cross-connected (so the left-hand socket contact on one telephone goes to the right hand one on the other, for example). These means the batteries end up in series adding their voltages.

I must dig out one of my sets and reverse-engineer it. It won't take too long...
TonyDuell is offline