Loud Buzzer Output Required

[TFcroft4 0]

I have been developing a timer/clock project using Monotronix SBC44B and DEV16T boards. The SBC44B board has cPU RTC RS232 and EV16T has LCd buttons and buzzer

 

I have used the built in buzzer for a count down timer. I have used the buzzer routines in the Monotronix demo code which outputs to C2. The prototype is fine but the sound output is too quiet.

 

I am now using a Serial LCD board so can replace the DEV16T board with a prototype board. ( re wrote lcd library to drive the serial screen via I2C and used keypad input too)

 

I have tried linking a peizo buzzer to mimic the DEV16T circuit which is a piezo PCB buzzer driven from C2 returning to ground via a resister. Instead of getting a short buzz each second I am getting a background buzz which seems to be synched with the I2C timing ( I am reading RTC every 250ms). I can identify the per second buzz but it is swamped by the other sound signales.

 

I have also tried sending C2 output to a small pre amp - amp and 8 ohm loadspeaker - similar type of sound just louder.

 

Can any one offer advise - I would like to get a countdown buzz with a longer (higher tone) on 0 seconds. beep-beep-beep BUZZZZ