I need to build a circuit that will take a square wave signal (between 1KHz and 10 KHz) and output a voltage that is linearly related (or as much so as possible) to the input frequency. I am only allowed to use capacitors, resistors, and diodes. Can anyone give me any tips on this circuit? The circuit also should be able to handle any type of wave and any frequency between 100Hz and 250KHz without, you know, blowing up or whatever. Thanks to anyone who can help!