Can anyone check my work?

[eightsevenzero]

I've been starting to create my own circuits and this is my first basic JFET overdrive idea. Works pretty great, FETs are biased at around 4.5V each. Since I've never really had formal training or anything I'd love to get some critiques on how anything could be better here. The only main issue I have at this point is there's a slight reoccurring click that happens once every few seconds. I've had this happen with my prototyping setup before so I'm not sure if it's an odd coincidence or if there's some insufficient filtering in this design? Any help would be appreciated, or any ideas of where to go from here!

[iainpunk]

welcome to the forum

i don't see why your circuit should click once in a while, maybe its the board that makes the click?

one pointer, the 56k resistors parallel to both gain and volume pot, they are redundant, in combination with the DC blocking cap, the filter's cutoff is already super low (about 1Hz), so having that resistor there is just some un-necessary load on the preceding gain stage. you can leave them out.
you can replace those 4.7uF caps with 100nF caps, which is better for signal paths, since the 100nF caps aren't electrolytic. (electrolytic caps in the signal path is generally an inferior solution, foil or polyester caps are better suited)

cheers

[antonis]

Plz post a schematic of particular power supply..
(unless it's incorporated into that "humble" breadboard..)

Check for proper electro caps (10μF & 4.7μF) orientation..

[eightsevenzero]

Thanks iainpunk! Super helpful.

The power is supplied from the proto box, its a 5-15v.

[anotherjim]

We might say you should plan for some power filtering/polarity protection. This particular design is partly immune. The gates are at 0v, the source is AC bypassed so some power supply noise immunity exists. However, supply noise can appear at the drains and be audible and get amplified by the second stage, so something like a 100uF cap can be added across the 9v supply. When breadboarding, some capacitance on the power strips helps keep out noise and should be done no matter how good your power supply is.

Not much could be damaged with reversed polarity, but if you add supply caps, they could be blown in that event, so a polarity protection diode is still a good idea.

I would say some immunity against RF interference might be added to the input. A low pF value cap from the input gate to 0v would do it, no larger than 100pF.

[fryingpan]

Why two different JFETs? Not that it matters for a self-build.

[eightsevenzero]

Mainly my stock of J201's is low and a had quite a lot of the 5458's. After swapping the first J201 for the 5458 I liked the tone better that I was getting with one of each too. 👍🏻