INFANEM the driving notion clone

[eatyourguitar]

I have about 40 units of 2N5088. 5 of MPSA18. 2 of MPSA12. no luck on the MPSA18 MPSA12. tested half of the 2N5088 but it looks like this batch can not be used. I need to buy some 2N5089 from 5 different brands from 3 different suppliers. that should be better to find the batch with reverse gain. I know that when I find it, the whole batch will have similar properties. this is why I am not going to test the rest of these 2N5088. I already know they have no reverse gain without testing all of them. one odd thing I noticed is that my skin resistance and skin capacitance enables good negative gain so maybe I just need to think about adding some caps or resistors to the circuit?

negativegain.jpg (116.7 KiB) Viewed 4905 times

[eatyourguitar]

ok so I think I got it. I had to bias the transistor exactly like it is in the driving notion schematic. all my 2N5088 are good. none of them failed the test. no variation at all. they all have reverse gain. the gain is less than 1 probably a 0.66 Beta for Q6. Q7 is interesting because of the germanium diode and the negative feedback cap. that should theoretically decrease gain but it also performs some increase in harmonics and some non-linearity. I would think combined the two gain stages will be a total beta of 0.45 or less. this makes me think that the low side is louder than the high side when the mix is in the middle. can anyone confirm this? I think to compensate it would be better to use 2nF or 3.3nF in C10 to increase gain if you are looking at the dead end fx schematic. in the notes he wrote that it increases brightness but I think it increases gain on the high side and lets more low frequency into the high side signal chain. more gain in the high side = more brightness overall from the pedal but I don't think bigger AC coupling caps with lower impedance at low frequency results in increased high frequency through the cap obviously. probably that was what was meant but it got lost in translation because it is a build guide not a research paper.

[ianmarks]

Cool. Did you use trimpots to bias q6 and q7 in place of the 100k coming off the emitters? Were you able to get the voltages in appropriate ranges with the Dilligaf build doc? I know those two are pretty particular.

[eatyourguitar]

I didn't check voltages. I will do that tomorrow. the load resistor on the output is because my scope input is 1M so I decided I should load it. the 2uF film cap is not really required but it was convenient to recycle stuff that was already on the breadboard. any input cap would work. the test signal is mostly sine so the only thing that matters is cap + input resistor impedance for a given test tone frequency. I think this was at 250Hz. I have control over the volume of the input test tone so I was not concerned with adjusting the resistor R2 and the cap C10. it was easier to adjust the volume of the input test tone on a knob to find the sweet spot.

reversegain.gif (3.29 KiB) Viewed 4848 times

[Paul_C]

Are we all friends again now ?

[eatyourguitar]

Are we all friends again now ?

I don't know. last post from digit was pretty salty. I asked for the schematic so I could help OP, he said no. I asked again, he ghosted me. he showed up here to sell his clone of my PCB in my thread. He said he can't share the schematic because it is not finished. then he said it is finished but he can't share it because he doesn't own the rights to it. this was a lie. I said whenever the schematic is released I will finish the pedal. He posted it to his website and sent emails to all his subscribers but he ghosted me again and tried to keep the schematic hidden from me. I found it anyway. it is public information. so either he lied about not having ownership of a schematic he made himself or he is posting a schematic that he doesn't have rights to. the more I think about it I think this was just a trick to protect himself from getting taken to court for trademark infringement. He technically could say that he never published the INFANEM schematic because he published the DILLIGAF. so I made it impossible for him to comply with my request legally because I didn't ask for the DILLIGAF schematic. I asked for the INFANEM schematic. it could be that he wants to help but his lawyer is preventing him from saying "ok here is the INFANEM schematic I made". he could actually be a nice guy who is doing only what he can legally and in public. but he came here with an attitude, he made his money copying my work, he gave me a shitty attitude, called me a thief, and named the pedal "Do I Look Like I Give A Fuck". I gave him credit for his contribution. still not sure if he is scared of trademark litigation or he just cares about ripping people off and making money more than he cares about the community and helping people build guitar pedals. I guess I will never know. he made his money so I don't think he is coming back.

[PMowdes]

[eatyourguitar]

I only came back to say that the pedal was completed and delivered. I gave away some passive feedback loopers and a handheld noise generator because I felt bad about how long OP was waiting. He was nice about everything though and he didn't make any demands for free stuff. I just don't have a need for guitar pedals anymore. I don't even own a delay pedal to make the feedback loopers do something cool. my guitar is broken. I don't have an amp. I had to go to a guitar shop to test it out before shipping so now the owner is mad at me because I just go there to test out a pedal. I'm in the process of looking for a real job. I am really close to not paying rent where I live after they raised the rates. I figured out that this driving notion has great sounding lows. the highs are ok but I think the highs can be replaced with a triple fuzz or at least the part of the triple fuzz after the first transistor. this pedal is a little weak in the mids but it is good if you like scooped mids. better than an amp with scooped mids because this pedal will track all over the neck. the design is interesting.