@AnalogKidPlus this is a project for school so i have to stick with the main premise of the course.

HEY -

There is a forum here for homework problems, where we don't give out the answers.

ak

 

HEY -

There is a forum here for homework problems, where we don't give out the answers. Next time, USE IT.

ak

This isn’t homework it’s a personal problem I’m showing to my class/ teacher to show what can be created. I had personal problems with the circuit. It wasn’t homework.

 

What values for Rtf, Rtv, and Ct give a value of 1261 Hz?

You need a resistor in series with the base of Q1, otherwise the base current is essentially the short-circuit output current of the 555.

Not sure this is necessary. The Discharge output is just an open collector, so will simply ground the base when activated, surely?

 

You are correct about the discharge output, but Wally is talking about the output transistor that drives the buzzer, marked Q1. With the grounded emitter and the base connected directly to the 555 output pin 3 (rated for 300 mA), this basically puts a diode directly across the output, shorting it to GND whenever it goes high. Not sure which part will fail first, but somebody gonna die.

What are the little numbers sprinkled around the schematic?

ak