•  
  •  

Low cost intercom using transistors

The circuit comprises a 3-stage resistor-capacitor coupled amplifier. When ring button S2 is pressed, the amplifier circuit formed around transistors T1 and T2 gets converted into an asymmetrical astable multivib-rator generating ring signals. These ring signals are amplified by transistor T3 to drive the speaker of earpiece.

Current consumption of this intercom is 10 to 15 mA only. Thus a 9-volt PP3 battery would have a long life, when used in this circuit.
For making a two-way intercom, two identical units, as shown in figure, are required to be used. Output of one amplifier unit goes to speaker of the other unit, and vice versa. For single-battery operation, join corresponding supply and ground terminals of both the units together.

The complete circuit, along with microphone and earpiece etc, can be housed inside the plastic body of a cellphone toy, which is easily available in the market. Suggested cellphone cabinet is shown.

If there are any problems please contact webmaster@electronic-circuits-diagrams.com

Please share & like

USED A20B-8200-0542 FANUC PLC CONTROL BOARD
$2954307.0 USED A20B-8200-0542 FANUC PLC CONTROL BOARD picture
NEW A06B-6122-H075#H550 FANUC SPINDLE AMPLIFIER
$22770.0 NEW A06B-6122-H075#H550 FANUC SPINDLE AMPLIFIER picture
2200 PCS FACTORY SEALED SLE66CX322P4.2B 07220 Infineon Technologies OBSOLETE
$22000.0 2200 PCS FACTORY SEALED SLE66CX322P4.2B 07220 Infineon Technologies OBSOLETE picture
NEW A06B-6122-H075#H500 FANUC SPINDLE AMPLIFIER
$20217.0 NEW A06B-6122-H075#H500 FANUC SPINDLE AMPLIFIER picture
NEW A06B-6141-H055#H580 FANUC SPINDLE AMPLIFIER
$20217.0 NEW A06B-6141-H055#H580 FANUC SPINDLE AMPLIFIER picture