As far as we are concerned we are looking for a function generator or a VCO (voltage-controlled oscillator). We would love to know which specific component we need. EDIT: What we are actually trying to achieve is to make two sine sound waves. One is constant and the other can be changed by hand with a potentiometer or so. For example if the consta
nt is 440Hz, the other can be changed between 170Hz to 270Hz or something similar. Another timer will turn on and off an electromagnet, it will be turned on and off with a frequency linear to the changing sound wave`s frequency.