Hi there, I'm trying to set up a simple oscillator that outputs 48kHz, however despite many different attempts all have fallen flat.

At present I am trying a 555 approach which is relatively simple, calculations as follows:

1440/48000 = 0.03 = (R1 + 2R2)xC1 [r1, r2 in kohm, c1 in uF]

(r1+ 2*r2) x 0.1u = 0.03

r1 + 2*r2 = 0.3k = 300 ohm

220 + 2*50 = 330 ... so a rough approximation, but should approach 48kHz.

In order to see the output I am using a ghetto oscilloscope, basically an audio line hooked up in the circuit where you would normally put an oscilloscope, and the other end into my mic jack. It works surprisingly well.

The problem I am having is that as I scale down the capacitors I lose 'sight' of any frequency. I have tried the above implementation, and a different implementation as seen in the circuit diagram attached that used 1k for both R1 and R2 and 10nF as my C1, but when I couldn't see the results as I scaled down to 10nF I instead opted for the above one which uses a larger 0.1uF capacitor.

As the results seem rather consistent before I hit 0.xx u, I know I am on the right track, but not sure how to resolve this situation. Any ideas?

The result for C1=470uF in the sound program has been attached, as well as that for 47u, and 0.1uF. 0.1uF might just even be 'noise', and not the pulses, as its a sine wave not square.

Below are the results I obtain from experimenting with different caps:

C1 Period Freq

470u 0.167 5hz

47u 0.016 62hz

10u 0.004 250hz

1u 0.00035 2857hz

0.1u 0.0002 5000hz <- off by a factor of ten

At present I am trying a 555 approach which is relatively simple, calculations as follows:

1440/48000 = 0.03 = (R1 + 2R2)xC1 [r1, r2 in kohm, c1 in uF]

(r1+ 2*r2) x 0.1u = 0.03

r1 + 2*r2 = 0.3k = 300 ohm

220 + 2*50 = 330 ... so a rough approximation, but should approach 48kHz.

In order to see the output I am using a ghetto oscilloscope, basically an audio line hooked up in the circuit where you would normally put an oscilloscope, and the other end into my mic jack. It works surprisingly well.

The problem I am having is that as I scale down the capacitors I lose 'sight' of any frequency. I have tried the above implementation, and a different implementation as seen in the circuit diagram attached that used 1k for both R1 and R2 and 10nF as my C1, but when I couldn't see the results as I scaled down to 10nF I instead opted for the above one which uses a larger 0.1uF capacitor.

As the results seem rather consistent before I hit 0.xx u, I know I am on the right track, but not sure how to resolve this situation. Any ideas?

The result for C1=470uF in the sound program has been attached, as well as that for 47u, and 0.1uF. 0.1uF might just even be 'noise', and not the pulses, as its a sine wave not square.

Below are the results I obtain from experimenting with different caps:

C1 Period Freq

470u 0.167 5hz

47u 0.016 62hz

10u 0.004 250hz

1u 0.00035 2857hz

0.1u 0.0002 5000hz <- off by a factor of ten