Transistor being affected by nearby oscillator

[netnews.comcast.net]

I have a piezo buzzer that is controlled via a pic microcontroller, through
a transistor. Problem is, when I designed a newer circuit to make the
beeper louder, I now have the buzzer making a quiet tone all the time when
the transistor should be 'off.' The newer circuit replaces a straight up
+VDC to the positive terminal of the buzzer, with a voltage doubling IC from
fairchild. Everything seems like it would work if the transistor were a
physical switch, but I don't understand enough about them to know what is
going wrong. Could I simply replace the transistor with a solid state
relay, or am I missing something here? Thanks,

-- Jeff


Pic --> Transistor -->Gnd
______^ ^
| |
Buzzer <-- Voltage doubler circuit <-- VDC+


It

 

[Mukesh Tatiya]

I have a piezo buzzer that is controlled via a pic microcontroller, through
a transistor. Problem is, when I designed a newer circuit to make the
beeper louder, I now have the buzzer making a quiet tone all the time when
the transistor should be 'off.' The newer circuit replaces a straight up
+VDC to the positive terminal of the buzzer, with a voltage doubling IC from
fairchild. Everything seems like it would work if the transistor were a
physical switch, but I don't understand enough about them to know what is
going wrong. Could I simply replace the transistor with a solid state
relay, or am I missing something here? Thanks,

-- Jeff


Pic --> Transistor -->Gnd
______^ ^
| |
Buzzer <-- Voltage doubler circuit <-- VDC+


It

Hello Jeff,
try using the IC CD4066. It will solve ur problem.


Mukesh tatiya

 

[Robert Baer]

I have a piezo buzzer that is controlled via a pic microcontroller, through
a transistor. Problem is, when I designed a newer circuit to make the
beeper louder, I now have the buzzer making a quiet tone all the time when
the transistor should be 'off.' The newer circuit replaces a straight up
+VDC to the positive terminal of the buzzer, with a voltage doubling IC from
fairchild. Everything seems like it would work if the transistor were a
physical switch, but I don't understand enough about them to know what is
going wrong. Could I simply replace the transistor with a solid state
relay, or am I missing something here? Thanks,

-- Jeff

Pic --> Transistor -->Gnd
______^ ^
| |
Buzzer <-- Voltage doubler circuit <-- VDC+

It

The "voltage doubler" is doing the deed; first check bypassing against
what the data sheet recommends.
Also re-check on how you have the beastie connected.