I just wired this up with some germanium PNP's taken out of an old Japanese radio and it sounds UN-REAL. Thank You! Hot Tip: By switching the positions of the 470 and 8.2K resistors you get a lot more volume!!
This brings back fond memories of buying a bunch of NTE AC128s and plugging each one into my old Radio Shack VM to sort them by HFE and playing with input / output DC blocking cap values. Oh, and if you want a bit less gain you can always bump the feedback resistor to 150K or 200K. 😃
Your recommendation on adding a cap to remove oscillation fixed my problem!(Edit note: The extra cap darkened my tone a bit, so I put a resistor on the wiper leg of the fuzz pot. That fixed my problem and left the tone unchanged). I love this video and your others are in my queue. Could you do a fuzz factory analysis? I think it would pair nicely with your fuzz face video. Thank you and please keep it up!
Wow, that's awesome to hear. Glad the vid helped! Maybe I'll take a look at a Fuzz Factory video in the new year. I'm currently focused on designing a handful of circuits.
1:27 that's called "split emitter resistance" (It's used a lot when you want a high, but controlled gain; a compromised solution) and helps to stabilize the gain, making "re" (the dinamic, internal base-emitter resistance) less relevant in the circuit. It's the same as setting the fuzz control at 9/10 of the total travel, there is a small resistance between the capacitor and the emitter (that capacitor is feedback path for the AC signal, when the pot is at its maximum, there is only "re" (internal) between Q2 emitter and ground) That's why a "REV LOG" pot in fuzz control is more functional than a linear/log one (you want fine control towards the end of the travel, so you can leave a very small "split emitter resistance" if you want)
9:00 The input impedance of Q1 (without considering the feedback) can be considered more or less equal to the resistance of the transistor, or "r pi" (r pi= Vt/Ib, or r pi= beta (Hfe)/gm). If "gm" is 0.0088 siemens, and beta of Q1 is 90, the impedance would be 10k (but "beta" is real life is Ic/Ib, it's usually slightly different from the value that the manufacturers give us, because it varies depending on the current and t°. In the real circuit, Z will be sligtly lower due to the feedback effect (100k) and fuzz control 9:35 In this configuration, AV gain can also be calculated as Rc/re* (*dynamic resistance of the emitter; there is no external physical resistance ,only the internal resistance between base and emitter). re = Vt/Ic, or re=1/gm . Again, in the circuit it will be lower due to feedback effect of 100k res.
Great video! I have a question, where would you put the 3 PDT switch? Does anyone have a schematic with it included? And what is the pinout for the switch, having trouble with this part. Thanks!
If you ever wanted to try to make a guitar effect this is the best beginner circuit to try. I made the NPN variant. So get that schematic. Don't worry about silicon vs germanium transistors either. Silicon works just fine. Any small signal transistor ought to do it. You can ballpark the parts in this whole circuit and it should do something. As long as the values you use are kind of close. Really, the more messed up it is the better. Then it'll be extra fuzzy.
I disagree about the FF being a good place to start. It's surprisingly tricky for how few components there are. The circuit is prone to unwanted oscillation, and finding the right transistors can be tricky and tedious. I would recommend an opamp-based booster, or an orverdrive as good candidates for circuits to start with.
@@theandromedacorporation I built a fuzzface and I used whatever random transistors I had lying around and it worked. Perhaps I just got lucky? What impressed me the most was the simplicity of the circuit. There's just not much to a two transistor fuzzface. It's amazing so little can do anything. Some overdrives can be simple. The one I built wasn't. It was all of them in one. I used an authentic vintage JRC4558 in it too. I salvaged a few off an old circuit board. So I know they're the real deal. Although anyone with ears should be able to tell themselves. You can check it out on instructables website, the article is titled, "GM Arts Overdrive Pedal Build"
In Common emitter configuration the Av (amplification) is equal to the gm = Ic/Vt times the load collector resistance (which I doubt is just 33K since the collector sees also the Rpi of Q2). Usually having an amplification depending from gm is bad since it highly depends on temperature (Vt = KT/q k boltzmann constant T temperature in kelvin q electron charge)
@@qddk9545 "gm" is "transconductance" (it's measured in Siemens) , it's the RATIO between input voltage (at base) /output current (at colector) . In BJT transistors it's an exponential function, that's why you get high numbers . Hfe (or "beta") is a RATIO between the input current at base (Ib) and the output current at colector (Ic). It's not "gain" per se, it's the ratio between those 2 currents. Voltage gain (Av) depends on the circuit design. And here we are calculating voltage gain (voltage comes in (induces a little current into the base) and you translate the output current (Ic) into voltage
On second thought, it might be the case in this sort of circuit because the exception is the rule due to intentional clipping, overdrive and what not. 😂
@@theandromedacorporation I mean, the last filter from my calculations is 3.1 Hz, not 31 Hz. f = 1/(2piRC) = 1/(2pi*500E3*0.1E-6). Also if you could show us how to get to 14 Hz on the first filter I would really appreciate 'cause I'm struggling with that one.
@@danielfc You're right! 3Hz, not 30! It's that damn capacitor conversion from uF to F. I'm always moving the decimal place the wrong amount of digits.
![[MPD직캠] 베이비몬스터 직캠 8K 'LIKE THAT' (BABYMONSTER FanCam) | @MCOUNTDOWN_2024.6.13](http://i.ytimg.com/vi/8qa-nm9bCLs/mqdefault.jpg)
![[MPD직캠] 베이비몬스터 치키타 직캠 4K 'LIKE THAT' (BABYMONSTER CHIQUITA FanCam) | @MCOUNTDOWN_2024.6.13](http://i.ytimg.com/vi/h99J4vWm7Ew/mqdefault.jpg)
![จังหวะนี้ - เม้ก อภิสิทธิ์ [ Official MV ] จอนนี่มิวสิค](http://i.ytimg.com/vi/4gQRZCkRyiU/mqdefault.jpg)
There's a massive problem with your videos. There aren't enough of them.
Thanks! I’m working on it. Tryna post every other Friday.
Please keep these videos up! Absolute gems.
Thank you. That's very nice encouragement. I'm used to the internet being needlessly pedantic and argumentative, so this is a lovely change of pace.
Such a perfect and simple circuit. 1 battery. 1 case. 2 jacks. 2 transistors. 3 caps. (5 with your improved version), 4 resistors.
These videos are exactly what i was looking for thank you
Great video!You explain the circuit thoroughly!Enjoyed the 'exit-music' as well!
yes man! thanks for that vid :) much love!
Would be cool to see the pedal side by side and walkthrough the schematic alongside the pedal. Great info nonetheless.
I just wired this up with some germanium PNP's taken out of an old Japanese radio and it sounds UN-REAL. Thank You! Hot Tip: By switching the positions of the 470 and 8.2K resistors you get a lot more volume!!
This brings back fond memories of buying a bunch of NTE AC128s and plugging each one into my old Radio Shack VM to sort them by HFE and playing with input / output DC blocking cap values. Oh, and if you want a bit less gain you can always bump the feedback resistor to 150K or 200K. 😃
thank you
Your recommendation on adding a cap to remove oscillation fixed my problem!(Edit note: The extra cap darkened my tone a bit, so I put a resistor on the wiper leg of the fuzz pot. That fixed my problem and left the tone unchanged). I love this video and your others are in my queue. Could you do a fuzz factory analysis? I think it would pair nicely with your fuzz face video. Thank you and please keep it up!
Wow, that's awesome to hear. Glad the vid helped! Maybe I'll take a look at a Fuzz Factory video in the new year. I'm currently focused on designing a handful of circuits.
1:27 that's called "split emitter resistance" (It's used a lot when you want a high, but controlled gain; a compromised solution) and helps to stabilize the gain, making "re" (the dinamic, internal base-emitter resistance) less relevant in the circuit. It's the same as setting the fuzz control at 9/10 of the total travel, there is a small resistance between the capacitor and the emitter (that capacitor is feedback path for the AC signal, when the pot is at its maximum, there is only "re" (internal) between Q2 emitter and ground) That's why a "REV LOG" pot in fuzz control is more functional than a linear/log one (you want fine control towards the end of the travel, so you can leave a very small "split emitter resistance" if you want)
9:00 The input impedance of Q1 (without considering the feedback) can be considered more or less equal to the resistance of the transistor, or "r pi" (r pi= Vt/Ib, or r pi= beta (Hfe)/gm). If "gm" is 0.0088 siemens, and beta of Q1 is 90, the impedance would be 10k (but "beta" is real life is Ic/Ib, it's usually slightly different from the value that the manufacturers give us, because it varies depending on the current and t°.
In the real circuit, Z will be sligtly lower due to the feedback effect (100k) and fuzz control
9:35 In this configuration, AV gain can also be calculated as Rc/re* (*dynamic resistance of the emitter; there is no external physical resistance ,only the internal resistance between base and emitter). re = Vt/Ic, or re=1/gm . Again, in the circuit it will be lower due to feedback effect of 100k res.
you calculate 14Hz cutoff at the input. What resistance value are you using? This must include the base to emitter of the transistor, yes?
Great video! I have a question, where would you put the 3 PDT switch? Does anyone have a schematic with it included? And what is the pinout for the switch, having trouble with this part. Thanks!
why is the Vbe of q1 just 0,2 V ( I expect 0,7V) are those germanium?
Yeah.The original Fuzzface used germanium transistors, but there are plenty of variations out there that use lots of different transistors.
If you ever wanted to try to make a guitar effect this is the best beginner circuit to try. I made the NPN variant. So get that schematic. Don't worry about silicon vs germanium transistors either. Silicon works just fine. Any small signal transistor ought to do it. You can ballpark the parts in this whole circuit and it should do something. As long as the values you use are kind of close. Really, the more messed up it is the better. Then it'll be extra fuzzy.
I disagree about the FF being a good place to start. It's surprisingly tricky for how few components there are. The circuit is prone to unwanted oscillation, and finding the right transistors can be tricky and tedious. I would recommend an opamp-based booster, or an orverdrive as good candidates for circuits to start with.
@@theandromedacorporation I built a fuzzface and I used whatever random transistors I had lying around and it worked. Perhaps I just got lucky? What impressed me the most was the simplicity of the circuit. There's just not much to a two transistor fuzzface. It's amazing so little can do anything. Some overdrives can be simple. The one I built wasn't. It was all of them in one. I used an authentic vintage JRC4558 in it too. I salvaged a few off an old circuit board. So I know they're the real deal. Although anyone with ears should be able to tell themselves. You can check it out on instructables website, the article is titled, "GM Arts Overdrive Pedal Build"
One thing I don´t understand: Q1 has a hfe of 80, but the amplification is over 200, how can that work? BR
In Common emitter configuration the Av (amplification) is equal to the gm = Ic/Vt times the load collector resistance (which I doubt is just 33K since the collector sees also the Rpi of Q2). Usually having an amplification depending from gm is bad since it highly depends on temperature (Vt = KT/q k boltzmann constant T temperature in kelvin q electron charge)
@@shyne_on Maybe I just don´t understand it, but how can you boost a transistor with hfe (amplification factor) to 200?
@@qddk9545 "gm" is "transconductance" (it's measured in Siemens) , it's the RATIO between input voltage (at base) /output current (at colector) . In BJT transistors it's an exponential function, that's why you get high numbers
.
Hfe (or "beta") is a RATIO between the input current at base (Ib) and the output current at colector (Ic). It's not "gain" per se, it's the ratio between those 2 currents.
Voltage gain (Av) depends on the circuit design. And here we are calculating voltage gain (voltage comes in (induces a little current into the base) and you translate the output current (Ic) into voltage
Google schmitt trigger !
More
Just about done recovering from surgery. Will upload more stuff soon!
Can you make a npn fuzz face
Could you do one on some compression unit starting with the simplest possible. I did subscribe. Don't be difficult. Thank you
"Don't be difficult" lol
I don’t know why…. But given values don’t match up. Appreciate if you could work with real values. Thanks anyway.
On second thought, it might be the case in this sort of circuit because the exception is the rule due to intentional clipping, overdrive and what not. 😂
Which values do you mean specifically? I could've gotten something wrong here. I'm wrong about stuff all the time. Lol
@@theandromedacorporation I mean, the last filter from my calculations is 3.1 Hz, not 31 Hz. f = 1/(2piRC) = 1/(2pi*500E3*0.1E-6). Also if you could show us how to get to 14 Hz on the first filter I would really appreciate 'cause I'm struggling with that one.
@@danielfc You're right! 3Hz, not 30! It's that damn capacitor conversion from uF to F. I'm always moving the decimal place the wrong amount of digits.