Click change to change the frequency. When entering a frequency of a musical note, copy and paste a frequency (the number only!) from the list and then paste it into the entering bar. Otherwise, enter a custom frequency. ONE IMPORTANT THING!!! (scroll down) The tone plays in 1-second intervals, so when you click stop and it still plays, it is still playing that 1 beat. however, the delayed response should not exceed 1 second long. I cannot make this play one steady tone due to the limitations.
The slider bar doesn't update when you change the frequency directly. Due to limitations, I could not find the inverse function between frequency and the position of the slider. The slider is only intended for you to quickly slide to a frequency between 25 and 4186 Hz. ANOTHER THING!!! FOR THE SQUARE WAVE, THE FREQUENCY WILL ONLY VIBRATE 1000 TIMES MAX before the next time the "play note" block runs!!! So at any frequency higher than 1000, you will hear that the beep is cut off for a fraction of each of the 1-second periods.