On Thu, 08 Aug 2019, ahriman wrote:
On Thu, Aug 08, 2019 at 05:23:04PM +0200, Paco Esteban wrote:
- build another guitar pedal (EQ) for my dad. I built him one, but I think the design can be vastly improved.
Oh man, that sounds so cool. I wouldn't even know where to begin with something like that!
Well, is not that hard, really. There are tons of designs out there. You only have to pick one, order the components and start soldering either on a perfboard or, if you want more permanent results, on your home made PCB or even order one online. Finally, pick a good case and maybe paint it to give it your style.
On my first attempt (which my dad still uses) I used this design:
http://www.generalguitargadgets.com/effects-projects/eq/6-band-graphic-eq/
Things get more interesting if you want to understand what's happening with the signal and all that. There are some good youtube channels out there if you want to go down the rabbit hole. I highly recommend it, but your time will disappear quite fast :-P
On that design for instance I had to debug some problems it has. The most important one is that it cannot share a power supply with other pedals, as it splits the power rail to create a virtual ground (to supply the op-amps with positive and negative voltage). So if you share the ground with other pedals, you're effectively shorting the negative side to the circuit ground ... In summary it has to be isolated with its own floating supply or batteries.
Also, the power led affects one side of the power rails ... so I had to fix that too on the original design ...
Anyway, my idea is to find a better design or create my own based on this one and others now that I understand a bit better what's happening.
Cheers,