Geranium Transistor

Geranium Transistor Musical effects and instruments designed and made in Toronto by James Mulligan

I know, it's been a while since I've posted anything, and I still plan on getting out the pedals I teased months ago now...
11/24/2021

I know, it's been a while since I've posted anything, and I still plan on getting out the pedals I teased months ago now and making demos for them... Meanwhile, I started a new job, which is my big excuse, as my time is more limited and there are many distractions competing for what free time I have!

Anyway, here is my geranium that is still holding on, despite being in a disadvantageous location with little sun and it being the end of November and there is frost about. I feel you, geranium.

Sometimes I like to look at all my things together.(Demos for the bottom two still coming soon...ish? Art for the top th...
09/12/2021

Sometimes I like to look at all my things together.

(Demos for the bottom two still coming soon...ish? Art for the top thing that is barely sneaking into the photo coming maybe after that?)

Mm, these are looking gooood. I'll probably redo the top ones, though: it's not readily apparent in photos but the yello...
08/28/2021

Mm, these are looking gooood. I'll probably redo the top ones, though: it's not readily apparent in photos but the yellow is pretty transparent and the brown a bit inconsistent; I think it'll look better if I thicken up the former and thin the latter to make it pass easier (which worked quite well on the second layer for the bottom ones). But the designs are looking nice and they lined up pretty easily, which makes me happy.

Prints in progress for the next two pedals. These were supposed to be test prints but they're turning out pretty decent ...
08/24/2021

Prints in progress for the next two pedals. These were supposed to be test prints but they're turning out pretty decent so we'll see? Sadly the one on the right didn't transfer properly for the second layer; there's supposed to be more detail in the green, particularly at the top. The ink has been thinned a bit for next time.

Printing these takes a lot of time and effort - my previous pedals usually take at least 3-4 attempts to get everything good, after dealing with errors, poor transfer, ink gumming, accidental scratches, misregistered screens, getting to the last screen and finding everything is skewed way to one edge, etc., and due to metal requiring a longer dry time than paper or fabric I can usually only do one colour a day. These will be slightly simpler than previous - only three colours, not four - and I added additional registration marks which seem to be helping with alignment. I do enjoy the results when it's done, though, so it still feels worth the effort.

Cases drilled, screens made, printing for two designs commencing soon (and a third where I need to stop being lazy and a...
08/19/2021

Cases drilled, screens made, printing for two designs commencing soon (and a third where I need to stop being lazy and actually measure where the holes will be so I can finish its mostly-designed artwork).

Happy 6/26! For some reason Instagram refuses to actually share this post here, so click through it you want some hott b...
06/26/2021

Happy 6/26! For some reason Instagram refuses to actually share this post here, so click through it you want some hott battery replacement action!

06/23/2021

Got some new PCBs in! First up is my octave up, which sounds pretty great with some fuzz. Also great, but not in this video: octave in one loop of my Split-Band Effects Loop, mixing in some uneffected signal on the other loop, into the fuzz. I'll probably do a demo of that soon.

As ever, something always has to go wrong when ordering PCBs, but fortunately it was surmountable - I forgot to flip a PNP transistor's orientation, so initially one half of the rectified signal was about half the amplitude of the other (I'm surprised it worked at all?). I used surface mount, so unfortunately I couldn't just turn the transistor around, but fortunately the pinout does work for an NPN, which I had. Changing one resistor for biasing was the only other thing needed. If I get to the point of ordering more boards I may make this change the default; it sounds the same and costs a little less.

06/01/2021

So maybe this thing wants me to start a garage rock band and play Sonics covers? No diodes at first, diodes added in the second half.

Because nothing ever stays simple, the Green Ringer I breadboarded has become a bit more than that:
- added a resonant low pass filter to emulate a rolled-back tone k**b (which smoothes the octave up in a nicer fashion than a non-resonant filter)
- added a boost to the output to make up for volume losses from the smoothing filter (except the buffering I added actually reduces losses from the normal input, so even without it it's louder with just the filter, making this clean gain)
- decided, what the hell, let's add some feedback diodes on that boost because heck it sounds really good so let's put that on a switch

So it feels like a bit more than just a Green Ringer now? I'm not sure if I'd say it's my design but basically everything's a derivation of something. It's not a matter of ethics for me so much as ... pride, maybe? I don't want to do the same old things; when I build them my intention is to learn, maybe make a thing for myself. At what point it moves past that is ambiguous.

Mostly I am difficult, because I know no other way.

05/31/2021

Wanted to have a bit of a change, so I breadboarded up a Green Ringer for weird octave fun (paralleled with a slightly-delayed fundamental here). Took me a little while to figure out how to play with it properly - it prefers single notes with reduced harmonics (best done with a combination of backing the tone k**b all the way down and picking the string as close to the middle of where it's fretted and the bridge as possible).

Because I am difficult and don't want to use the k**bs on my guitar I then spent too much time trying to emulate the tone k**b on my breadboard, hah - not as easy as a simple low pass filter because of the interplay between the control and pickup-as-inductor, which has a slight resonance to it; I've gone with a slightly resonant Sallen-Key which comes close, but reduces the volume, so I'll probably add in a simple boost too. Whenever I get around to ordering more PCBs I'll probably throw a handful of these in there too.

05/24/2021

Harmonic tremolo is getting where it needs to be, so here's a bit of an old song of mine on bass (which agrees well with the filter sweep and resonance) with accompanying drum machine, because it's fun to play.

Sorted out most of the distortion issues, need to add back a little bit of gain but also reduce a little bit of noise (which strangely seem to be unrelated in this circuit, I am okay with that). A weird bit of DC offset on the output that shouldn't be there, probably related to the voltage inverter. A couple other fiddly things left. But: I spent a long time tuning and I think the sound is where I want it, so other than the gain matter (which I think I can handle with a pre-emphasis circuit I'm using to make dealing with the noise floor easier) I don't think I need to touch the sound shaping parts at all. Hurrah!

05/05/2021

Harmonic tremolo with saw wave, filter sweep maxed and about 2/3 resonance

I didn't expect to be finished with the harmonic tremolo so soon, but apparently I am? I'm happy with the circuit; just need to decide on my pot tapers and lay out the PCB and I can move on to the next phase. Yassss, looking forward to ordering more boards soon - this, fuzz, some more of the Phase Shift/Vibrato (still a few of those completed to sell, but I think I should get more boards on hand), and who knows what else? I had a distortion laid out but I don't have a breadboard build right now; maybe I'll build it up and see if I'm still happy with it.

05/04/2021

I think my fuzz design is where I want it, so back onto other projects that had been waiting - next up is harmonic tremolo! I think my original version was a bit over-complicated without being better, so I've rebuilt it a bit simpler. Only one resonant filter option (rather than resonant and non-resonant in parallel), but better focus. One thing this has allowed is an improvement on the filter sweep, which I'm demoing here. First, no sweep, then in phase with the trem, then inverted phase. Basically the same build complexity as in the previous version but with more functionality, so I'm pleased.

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Toronto, ON
M5H

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