Testing my new Rigol DS1052E 50 MHz scope. The circuit is made up of two 555 timers. The one on the left (monostable configuration) waits for the switch to give a pulse. When this happens, it will turn on the 555 timer on the right and allows a capacitor to charge. When the cap is nearly fully charged, it will turn off the right 555 timer. When the right 555 (astable configuration) is on it will generate a tone through the speaker by oscillating its output. The yellow trace shows the capacitor charging then discharging, and the blue trace shows the tone generated.
