simple diy intercom

[amateur_25]

hi

i want to make a simple diy intercom based on this circuit. from a security point of view as we were recently robbed.

https://circuitdigest.com/electronic-circuits/two-way-intercom-circuit-diagram

however this is similar to how walkie talkie works which isn't what i want.

can i just omit the spdt switch then join the wires together so you can hear both mics at the same time?

[fourfathom]

can i just omit the spdt switch then join the wires together so you can hear both mics at the same time?

Yes, you probably can.  You might need to reduce the value of the resistor (R3) that feeds power to the microphones.  If you get horrible distortion try dropping the value by half.

Also, in that schematic there is a 10K resistor (R1) connected the the amplifier output, through a capacitor.  I'm pretty sure that resistor should be 10 Ohms, not 10K Ohms.  That's there to stop oscillations.

[Canis Dirus Leidy]

As variant:  slightly more complex scheme, but with sidetone cancellation (i.e. full duplex).

P.S. It's also more power-hungry, but this is due to the use of more powerful (1W) amplifier IC and loudspeaker.