Ooh! I have a couple of questions.

[paul.creedy]

As part of my ongoing process of learning by experimenting, I made myself a second Happy Little Accident board.

Having completed the board I wired it up, but without switch, led, foot switch and (most importantly, I discovered) pots.

It worked ok as a fuzz, but didn't do the thing that made the HLA interesting i.e. the choppy tremolo effect as the note dies off.

I added a B100K to the input side to no effect, even with the transistors swapped from the finished pedal.

Finally I added the A100K volume pot, which made everything work as originally hoped, and I was able to fit some new transistors and still have it do what I wanted it to do.

So my questions are:

1. My mistake (I assume) was not to allow for the pot resistance, as even when fully up there is what amounts to a 100K resistor running to earth - could I have run a 100k resistor to earth from the output jack tip and achieved the same thing ?
(I'll try it later out of curiosity, but it's always helpful to hear from knowledgeable people whether or not my conclusions are right or wrong).

2. What is the pot/resistor actually doing to the circuit at that point, in this case in terms of producing the choppy sound ?

[mth5044]

Hello!

Is there are schematic, or

In general, leaving out a pot is like leaving out any other component. It's just one or two variable resistors and it's a pretty good chance that it impacts the functionality of the circuit drastically when not there.

[merlinb]

Presumably from this thread:
https://www.diystompboxes.com/smfforum/index.php?topic=122166.20
But they seem to be using yet different pot values...

[paul.creedy]

In other news, running one HLA into a second makes for even more choppy nonsense, so my next build (while waiting for some parts for a couple of other projects to arrive) will be two HLAs in one enclosure with one, or the other, or both available.

I could just make a second HLA and run them side by side, but two in one seems like a fun thing to do*




*plus I could then run the double HLA into the single one, for triple-choppy nonsense

[duck_arse]

the C and the R values connected to the E of the MPSA18, I found, were the major factors in the frequency/timing of the chop. leaving off the out pot, or increasing that resistance total beyond "a" point means no chop. however, the input level also has a big effect on to chop or not, driving w/ a fuzz gives a window of control, of sorts.

without the E connection operating on the mpsa18, I think the circuit is basically a bazz fuss, with added octaver transistor. [?]