potentiometer help, frequency?

Question

I am conducting a physics experiment where i have to determine which potentiometer is most practical at achieving our selected frequency range.
We are using logarithmic (Audio) and linear potentiometers (A50k, A500k, B50K and B500k)
We have selected songs and determined their BPMs and frequencies. We have set up a circuit using a bread board that will, with the use of a potentiometer, turn an LED off and on to the beat / frequency of a song.
So which potentiometer would best fit this frequency range and why?

Details: Frequency range is between 0 and 4 Hz

Answer 1

Yes, it does look like it's a 555, wired in classic astable configuration, and the potentiometer is being used to set the frequency. The answer to your question depends on the value of the timing capacitor and the fixed resistor (your fixed resistor is 2 resistors in series for some reason).

By the way the frequency will never go down to zero with this circuit.



Whether it is linear or logarithmic does not affect the frequency range. it only affects how the frequency changes as you turn the pot. You should have one wire going to the wiper and the other to one of the ends. If you connect it as shown in the image it will not work.

Answer 2

It looks as though your are using the 555 i.c.



There are many explanations of its operation on the net, where you will find the simple formulae to select appropriate component values in order to get it operating, in the astable mode, at a desired frequency.



You need to calculate a suitable range of resistance values and select a potentiometer and a series resistor to satisfy that requirement.

Answer 3

Human perception of frequency/time and amplitude are all logarithmic. Be sure you don't get a log pot wired backward. If you want the frequency to increase clockwise then you need a reverse log pot.

Also, your picture shows the pot connected wrong. You have to use the center pin.

Answer 4

For help in understanding 555 timers, check out the electronics tutorials on the subject at WISC-ONLINE.