Birdie electronic Doorbell ringer (one transistor)
This circuit is an electronic bell, it produce a tone like a real bird, useful as a doorbell, alarm, or between two rooms, floors like i did.
_ P1 is of experimental value. Start with 220 Ohms or so and modify to suit your needs, you can also change C3,C4,C5 to get more different tones, The transistor is a general purpose kind and is not critical, almost any
small PNP type will work.
_ L1 is a bell-transformer which is usually already present in the house, if you wish, you can use a battery instead of the bell transformer, Just hookup a 9-volt battery (or wall adapter) to The +/- .
_ Diode (D1) is required as a rectifier for use with the bell transformer and to protect the circuit from accidental polarity reversal.
_ L2 can be found in an old transistor radio, they look like miniature transformers and are usually colored red or green, you have to try with different transformers as the sound can vary depending on the winding.
_ The speaker is a 8 Ohm type and must be larger than 200milli-Watt. I used a 2Watt type, but anything over 0.2W will do.
This video shows the circuit working, by changing certain values you get mores sounds…
It really sounds like a bird and when you release the doorbell button the sound slowly fades away. I have used this circuit in my house, and even build the circuit for others.
Remember to have fun!!!