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 (or wall adapter)to points 'A' and 'B' (A=+) the
diode (D1) is to protect the circuit from accidental polarity reversal and is
optional, but required as a rectifier for use with the bell transformer.
T1 is a General Purpose PNP transistor and probably anything will work. L2 comes
out of an old am transistor radio. They look like miniature transformers and are
usually colored red or green. You have to fiddle with different transformers as
the sound can vary depending on the value.
The loudspeaker is a 8 Ohm type and must be larger than 200milli-Watt. I used a
2Watt type, but anything over 0.2W will do. 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 over 20 years and even build the "Birdie" for
others. Although an old circuit, the experimentation and the final results still
give a punch. Remember to Have fun!
Copyright © 1993 - Tony van Roon
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 (or wall adapter)to points 'A' and 'B' (A=+) the
diode (D1) is to protect the circuit from accidental polarity reversal and is
optional, but required as a rectifier for use with the bell transformer.
T1 is a General Purpose PNP transistor and probably anything will work. L2 comes
out of an old am transistor radio. They look like miniature transformers and are
usually colored red or green. You have to fiddle with different transformers as
the sound can vary depending on the value.
The loudspeaker is a 8 Ohm type and must be larger than 200milli-Watt. I used a
2Watt type, but anything over 0.2W will do. 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 over 20 years and even build the "Birdie" for
others. Although an old circuit, the experimentation and the final results still
give a punch. Remember to Have fun!
Copyright © 1993 - Tony van Roon
shall i used L2 is ordinary 9v step down transformer and T1 is any PNP transistor?
ReplyDeletethanks....
Positive site, where did u come up with the information on this posting? I'm pleased I discovered it though, ill be checking back soon to find out what additional posts you include. Video Doorbell Reviews
ReplyDelete