"petrus bitbyter" wrote in message
l.nl...

"Joe" schreef in bericht
...

"Joe" wrote in message
...
I just managed to get hold of unbuilt Heathkit alarm clock GC-1107.
The electrolytics were dry and the speaker is shot.
Finding replacement caps was easy, but does anyone here know the
impedance of this 2,5" speaker?
Is it "normal" 8 ohms or something more exotic?

-Jan



To clarify the circuit, the postive side of the speaker receives 17 volts
thru one diode and a resistor and the negative side is connected via
transistor to ground and the transistor is driven by 4001 IC.


Is it an ordinary electromagnetic speaker? Can't it be some of that piezo
parts? A 17Vpp is pretty high. Too high for a low impedance 2.5" speaker.
Try to connect some audio oscillator to it. If you hear nothing at
1kHz/10V then the speaker is really gone.

petrus bitbyter


A good clue as to whether its a piezo sounder is that some other component
would provide a DC path for the collector of the driver transistor - maybe
an inductor or just a resistor if its a real cheapie.