Thomas Burns
Published © GPL3+

Make an intercom system out of vintage rotary phones!

I built an analog circuit that would allow the phones to ring when the other receiver is raised.

IntermediateFull instructions provided4 hours2,332
Make an intercom system out of vintage rotary phones!

Things used in this project

Hardware components

Rotary telephone
×2
1uF 160V film capacitors
×8
1N4007 – High Voltage, High Current Rated Diode
1N4007 – High Voltage, High Current Rated Diode
×2
Transformer
One capacitor needs to put out enough voltage to operate the phone ringers. In my case this was 55V. The second transformer will power the speaking/listening part of the circuit—in my case this was 25V.
×2
Capacitor 1000 µF
Capacitor 1000 µF
This is the filter capacitor that smooths the DC coming out of the bridge rectifier. Should be rated for at least 50V.
×1
Project enclosure
I recycled a metal electrical switching box for this, but you can use anything.
×1
Female DC barrel jack with screw terminals
I used these for the telephone lines, to easily plug them into the control circuit
×2
Male, panel mount DC sockets
This is what mates with the female DC barrel jack connectors.
×2
5x7cm perfboard
×1
C14 power socket with fuse and switch
×1
M2 nylon standoffs (assorted)
×1
Rubber feet for enclosure
×4

Hand tools and fabrication machines

Wire Stripper & Cutter, 32-20 AWG / 0.05-0.5mm² Solid & Stranded Wires
Wire Stripper & Cutter, 32-20 AWG / 0.05-0.5mm² Solid & Stranded Wires
Ferrule wire crimping kit
assorted wiring
Soldering Station, Hobbyist
Soldering Station, Hobbyist
Step drill bit
Hand file kit
wire cutters

Story

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Schematics

Control circuit schematics

Credits

Thomas Burns

Thomas Burns

4 projects • 53 followers
Father, maker, and lover of analog electronics. Check out more of my builds on my YouTube channel!

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