I'm planning to build two pedals in one enclosure, and have a question about simplifying the power decoupling.
This is going to be a dual-Timmy, but I don't think the specific circuit makes much difference for my question; it's a dual-opamp overdrive.
The Timmy power supply is something like this:
V+ (9V) goes to the dual opamp; Vref (~4.95V) is used elsewhere in the circuit.
I want to add the 100-ohm + 220uF filtering as described by bajaman here: https://www.freestompboxes.org/viewtopic.php?f=49&t=1392
I know I could add that completely separate from the Timmy boards, but since I'm making the layout anyway, could I simplify it by putting the filtering after/within the power supply section, like this?
This is using the existing 47uF cap (x2) instead of the 220uF -- is that enough? Should I replace the 47uF with 220uF?
This filters the ~4.95V supply, and doesn't require me to duplicate the whole power supply section for each circuit. I'm hoping the opamps themselves don't really need the decoupling/isolation -- but I could be dead wrong. Anyone know?
Thanks!
Dual FX power decoupling, simplification
I think what I'm after is basically similar to the AnalogMan King of Tone: one enclosure, two independent and identical low/med-gain overdrives (each using a dual opamp) connected in series, with +9V referenced only by the opamps, and Vref (4.5~5V) referenced elsewhere throughout the circuit.
Going by Madbean's schematic for his Aristocrat (based on the King of Tone), there is no power isolation between the two halves. So I think I should be safe keeping the power supply section pretty simple.
Is there a rule of thumb for when you would really want to isolate/decouple power to multiple circuits? I'm sure it could never hurt, but how do you weigh the benefit vs the extra time/parts? Is it mostly recommended for very-different and/or higher-gain circuits?
Any advice would be appreciated. Thanks!
Going by Madbean's schematic for his Aristocrat (based on the King of Tone), there is no power isolation between the two halves. So I think I should be safe keeping the power supply section pretty simple.
Is there a rule of thumb for when you would really want to isolate/decouple power to multiple circuits? I'm sure it could never hurt, but how do you weigh the benefit vs the extra time/parts? Is it mostly recommended for very-different and/or higher-gain circuits?
Any advice would be appreciated. Thanks!
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If you have an LFO in one circuit (e.g. as part of a modulation effect) and another circuit that carried the audio, you would want separate filtering and separate vref circuits to avoid tick bleeding into the audio output. Two low-ish gain overdrive circuits probably won't present much of a problem, you might even be ok with them sharing vref as well as ground.
modman wrote: ↑ Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...