Birdie Doorbell Ringer

Additional Notes

P1 is of experimental value. Start with 220 Ohms or so and modify to suit your needs. The transistor is a general purpose kind and is not critical, almost any pnp type will work. L1 is a bell-transformer which is usually already present in the house. If you wish, you could use a battery instead of the bell transformer. Just hookup a 9-volt battery to points 'A' and 'B' (A=+) the diode (d1) is to protect the circuit from accidental polarity reversal and is optional. L2 comes out of an old am transistor radio. You have to fiddle with different transformers as the sound can vary depending on the value. 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 for many years and even build the "Birdie" for others. Have fun!