3 Police siren circuits using 555 timer
Here are police siren circuit using IC 555 with PCB layout. It uses IC 555s as a frequency generator and a transistor to drive the speaker. Read more
Alarm sounds
4 ideas of tone generator circuit using FET, SCR, transistors
This is simple Warble tone generator circuit , use scr as main of oscillator and signal will be boost, then feedback to SCR again. Output is 32 ohms speaker [….] Read more