Low-pass filter for audio out

[crispy_tofu]

Just wondering, did you use 10nF capacitors in the end for the circuit? Or did 33nF work fine?

[1461748123]

@crispy_tofu
I did end up using a 10nF capacitor, I will try the 33nF capacitor later

EDIT: I'm using a 10uF capacitor instead, not sure if 33nF will work..

[crispy_tofu]

Okay, thanks.

[cpaulik]

In case anybody does not want to buy resistors and capacitors. I think that you could use the resistors and capacitors from the old Gameboy board if you have one.

On there are resistors with 510 and 220 Ohms which would give us 1.1V and a cutoff frequency of 32khz if combined with a 10nf capacitor which can also be found on the board.

I'll try this later today but I think that should work if my calculations are correct.

[Camble]

In case anybody does not want to buy resistors and capacitors. I think that you could use the resistors and capacitors from the old Gameboy board if you have one.

On there are resistors with 510 and 220 Ohms which would give us 1.1V and a cutoff frequency of 32khz if combined with a 10nf capacitor which can also be found on the board.

I'll try this later today but I think that should work if my calculations are correct.

While that is technically true, I'd be relucatant to re-use capacitors from 25 year old equipment.

[crispy_tofu]

Definitely. Resistors are okay, but capacitors are usually a big no-no - especially from lower-quality brands. These capacitors may have been stressed a lot and are prone to failure.

[cpaulik]

Yes you are right. But I checked them and they still showed reasonable capacitance values. Anyway I do have sound now so I could confirm that my wiring works. Now I can order new capacitors or use a USB soundcard. I'm not yet sure.

[crispy_tofu]

If you have the equipment, you should also check the ESR values of the capacitors - these can go high and cause the circuit to go dodgy, even if the capacitance is fine.

[Jimanez11]

So, the local radio shack was out of .033uf caps, so i got some .047uf and a .022uf cap. Will either af these work for the filter? I have tried to recreate the filter based off of limited understanding of electronics schematics and the pictures (which are awesome), but am still getting nothing through the speaker. I have changed gpio 18 and 19 to PWM0/1, but i think,my fault is in the filter, electricity is still an abstract concept to me... Any help or guidance is appreciated. Everything is put together and functioning, just no sound (which is half of the experience).

[Helder]

I made an SMD version of this circuit that when it arrives I'd like to pass out to 3 people to test out in their setups (I don't have all my parts for my own build yet). I'd like to send one to you Brian and to 2 other people who would like to test it out, just pay shipping which is like $2.54.

Here is a mockup of the board:
1.10x0.69 inches


If it all works out good I'll release the links to buy this and a non SMD through hole component version.