Chuck D. Bones
Circuit Wizard
We can construct a fixed mid scoop with as few as two resistors and two caps.
CONTEST Buddy's Summer Contest - 1 Knob? No Prob!
- Thread starter BuddytheReow
- Start date
CONTEST
BuddytheReow
Moderator
You mean a simple notch filter? I need to spend some time trying those out. I don’t have LTSpice, so I’ll have to experiment the old fashioned way on a breadboard
bean
Legume Liaison
Here's my entry: the Killshot
The idea behind this was to come up with a one-knob stereo chopper tremolo with momentary bypass. My goal was to get a pretty aggressive square-wave that was suited for extremely fast speeds. So, say you're playing a Chordy-McChordery Smiths jam, or some crazy Winger solo: you hit the switch and everything goes ludicrous speed panning between the two amps.
For the audio portion, I went with a JFET input buffer, then split that into two channels. Each channel has a photocell (of an optocoupler) between signal and ground followed by a gain recovery stage and then output. I went with inverted gain stages because (1) it requires one less part and (2) since this is an "always on pedal" the input and output phase don't need to match.
For the LFO I used the 555 to make a square wave LFO. The output is connected to the mid-point of the two LEDs of the opto devices (placed in series) so that they toggle on and off in opposite fashion. When one LED is on, the corresponding LDR goes to near 0 Ohms thus pulling the signal to ground and its channel has no output. The other LED is off, so the other photocell is at full resistance, and thus signal passes through that channel to its output.
To trigger the effect, I used a simple transistor switch with about 10ms turn on time (to try and avoid any sudden popping). Two independent switches were required in order to keep the channels as separate as possible.
Here's the good: it basically worked almost perfectly from my initial design. I did make a few value adjustments here and there but I got the basic idea right from concept.
The less good: it's not choppy enough. This probably comes down to the opto implementation and transistor switching. Neither signal gets all the way grounded so there is a little bit of audio in the channel that's supposed to be "off". Also, there is a bit of clicky noise. I was able to reduce it some with the R5 and R10 pulldowns but it's still there.
Overall, it sounds good, but it's not good enough yet. I'll revisit this when I have more time. It's still on the breadboard so I may do a quick audio sample tomorrow.
The idea behind this was to come up with a one-knob stereo chopper tremolo with momentary bypass. My goal was to get a pretty aggressive square-wave that was suited for extremely fast speeds. So, say you're playing a Chordy-McChordery Smiths jam, or some crazy Winger solo: you hit the switch and everything goes ludicrous speed panning between the two amps.
For the audio portion, I went with a JFET input buffer, then split that into two channels. Each channel has a photocell (of an optocoupler) between signal and ground followed by a gain recovery stage and then output. I went with inverted gain stages because (1) it requires one less part and (2) since this is an "always on pedal" the input and output phase don't need to match.
For the LFO I used the 555 to make a square wave LFO. The output is connected to the mid-point of the two LEDs of the opto devices (placed in series) so that they toggle on and off in opposite fashion. When one LED is on, the corresponding LDR goes to near 0 Ohms thus pulling the signal to ground and its channel has no output. The other LED is off, so the other photocell is at full resistance, and thus signal passes through that channel to its output.
To trigger the effect, I used a simple transistor switch with about 10ms turn on time (to try and avoid any sudden popping). Two independent switches were required in order to keep the channels as separate as possible.
Here's the good: it basically worked almost perfectly from my initial design. I did make a few value adjustments here and there but I got the basic idea right from concept.
The less good: it's not choppy enough. This probably comes down to the opto implementation and transistor switching. Neither signal gets all the way grounded so there is a little bit of audio in the channel that's supposed to be "off". Also, there is a bit of clicky noise. I was able to reduce it some with the R5 and R10 pulldowns but it's still there.
Overall, it sounds good, but it's not good enough yet. I'll revisit this when I have more time. It's still on the breadboard so I may do a quick audio sample tomorrow.
Chuck D. Bones
Circuit Wizard
Interesting idea. I can see why you're not getting enough modulation depth.
Nostradoomus
Well-known member
bean
Legume Liaison
You sayin' "She's Only 17" doesn't hold up?
BuddytheReow
Moderator
Only a few days left, everyone! Some great entries so far!
Chuck D. Bones
Circuit Wizard
I thought the rule was "half plus seven."
Nostradoomus
Well-known member
Nostradoomus
Well-known member
How it started:
The Gator
Well-known member
Ok. Finally got something going!
I absolutely love the univox superfuzz. I also really like the two sticks of Derm as a one knob fuzz. However I would prefer if the one knob was actually controlling the fuzz on the two sticks of Derm, and not the volume.
The Super Fuzz is awesome, especially as an octave fuzz, but it has a lot of parts, especially electrolytic capacitors. So I wanted to build something that was simple like the two sticks of Derm, but with heavy fuzz kind of like a superfuzz. So this is my MOAR Fuzz 2.0
It is a four transistor fuzz using three 2n5088 and one S9018 npn transistors.
It also incorporates a mid cut kind of like the Super Fuzz has, only Built like the mid cut Chuck showed me how to build on a previous circuit. The Super Fuzz has to use a switch to incorporate this cut, whereas this uses a trim pot so you can dial it where you want it. Also it has a trim pot bias and a trim pot for overall volume. It could be dialed in just above Unity for the particular mid-cut you have set.
Please ignore the crossed out sections as they are not part of the circuit.
I will do a demo tomorrow!
I absolutely love the univox superfuzz. I also really like the two sticks of Derm as a one knob fuzz. However I would prefer if the one knob was actually controlling the fuzz on the two sticks of Derm, and not the volume.
The Super Fuzz is awesome, especially as an octave fuzz, but it has a lot of parts, especially electrolytic capacitors. So I wanted to build something that was simple like the two sticks of Derm, but with heavy fuzz kind of like a superfuzz. So this is my MOAR Fuzz 2.0
It is a four transistor fuzz using three 2n5088 and one S9018 npn transistors.
It also incorporates a mid cut kind of like the Super Fuzz has, only Built like the mid cut Chuck showed me how to build on a previous circuit. The Super Fuzz has to use a switch to incorporate this cut, whereas this uses a trim pot so you can dial it where you want it. Also it has a trim pot bias and a trim pot for overall volume. It could be dialed in just above Unity for the particular mid-cut you have set.
Please ignore the crossed out sections as they are not part of the circuit.
I will do a demo tomorrow!
Last edited:
Chuck D. Bones
Circuit Wizard
Why the S9018? A spare part from your R/C airplane?
The Gator
Well-known member
Good one!I have a ridiculous assortment of odd transistors. It was NPN, and hfe of 120.
I just wanted a clean low gain volume increase at the end of the circuit to help keep above Unity when utilizing the mid scoop.
The circuit is really a high gain fuzz face, with a buffer in front, then a mid scoop, and a clean boost at the end.
BuddytheReow
Moderator
Today's the last day everyone! Let's see what you've got!
Erik S
Well-known member
Needs more hot glue.Does this count? It uses exactly one knob
Light reflector made of an old knob reamed out with a dremel so I don’t have to wire up and place two LEDs perfectly. Just one superbrite does it.
fontoponto
Well-known member
Damnit is it that late? I guess I skip this competition 
BuddytheReow
Moderator
Time flies when you're not building...
fontoponto
Well-known member
I was building but different pedals...
BuddytheReow
Moderator
Aaaaaaaand....time!
That's it, folks. Thank you everyone who contributed. A total of 13 entries that all do different things. Great job, everyone! I thought there would be a bit more turnout, but oh well. That's the summer for ya
. I'll need a little bit of time to finish breadboarding everything and determine a winner.
Of course, if anyone still has something they're finishing up feel free to contribute for completeness. Cross talking is definitely welcomed here to help others make their creations better!
That's it, folks. Thank you everyone who contributed. A total of 13 entries that all do different things. Great job, everyone! I thought there would be a bit more turnout, but oh well. That's the summer for ya
. I'll need a little bit of time to finish breadboarding everything and determine a winner.Of course, if anyone still has something they're finishing up feel free to contribute for completeness. Cross talking is definitely welcomed here to help others make their creations better!