Still problem with 556 circuit - please help

Hi to all.

Further to a previous post where I asked if a tranny was correct I have built another copy of the chirp generator, and yet again it doesn't work.

I replaced the 2n3904 on the drawing with its coplimentary 2n3906 hoping this would solve the problem as advised on the forum, as the drawing stated a 2n3904 in the text but showed a pnp tranny in the drawing.

The problem I have is that the output to the piezo beeper is only giving very quiet clicks, and i mean quiet, you need to concentrate to hear them at all.

I know the sounder is ok ( its from a fire alarm system, one of the kind with dip switches that can be changed to give sirens etc ) as when I tested it and set it on continuous I was nearly deaf by the time I'd done. It draws 9.5mA on full volume at 12v dc.

The pics are the best I can get and the wires from the board are as follows -

Red = 12v +
Yellow = Ground
Bell wire goes to siren ( it has a line along one side so I know which is pos)

Anyway if anyone has any suggestions I would be forever grateful and absolutely overjoyed if I ever get this little devil working.

Thanks for looking.......Al

Hi to all,

Just to say I solved the problem, with another piezo buzzer!

Which means I have yet another working circuit! hooray.......Al