Schematic check !?!?!?!?!

[Dragonfly]

here's a design for a fuzz pedal that i came up with..i havent built it yet (gotta get some 10k pots:) ), but could be pretty cool...and a pretty easy build too.  anyway, i was hoping you guys could look it over and see if you can identify any "trouble spots".... once the design is finalized, i'll post the schematic in the "layouts forum"  

http://aronnelson.com/gallery/Dragonfly-FX-Schematics-%21/DRAGONFLY_FX_DEVILS_RIGHT_HAND?full=1

as always, suggestions and comments are ALWAYS welcome !

thanks in advance !

Andy

[Oliver]

Hi,

as i played around with the LM386 and the LittleGem Circuit i noticed, that
the Gainpot don't have to be bigger than just 2K...

Thats because at the Pins 1 and 8 of the IC there is an integrated Resistor of 1.35K.
With a 2 or 3 K Pot You will have a "Gainrange" about the complete range of the Pot. With 5 or 10K There is only a little Part of the adjustment range of the Pot.

And it's interesting to play with a Cap in Series with the "Dirt" Pot..
That has influence of the Frequency in the Distortion.
For the LittleGem i used a 2.2uF with good result (perhaps try for your taste)

bye
Oliver

[Dragonfly]

Hi,

as i played around with the LM386 and the LittleGem Circuit i noticed, that
the Gainpot don't have to be bigger than just 2K...

good to know...i figured i might go with a 1k, but decided a 10k was "safer"...but on your suggestion, maybe i'll go with a 2k pot...

Thats because at the Pins 1 and 8 of the IC there is an integrated Resistor of 1.35K.
With a 2 or 3 K Pot You will have a "Gainrange" about the complete range of the Pot. With 5 or 10K There is only a little Part of the adjustment range of the Pot.

makes sense....

And it's interesting to play with a Cap in Series with the "Dirt" Pot..
That has influence of the Frequency in the Distortion.
For the LittleGem i used a 2.2uF with good result (perhaps try for your taste)

i had considered a 10uF in series...going by memory (from a while back), it seems like that was the datasheets recommendation...but like i mentioned, thats *memory*, so i'm probably mistaken...

bye
Oliver

thanks for your input !

andy

[Oliver]

Hi,

You cant damage the IC by shorting the PINS 1 and 8 so try out Potvalue as you like.... I used 1K but with that i couldn'd turn it to clean sound.
So i took the next step up = 2K2 with good result for my taste.

As in the Datasheet - they say - using a 10uF Cap - i tried several caps and came to the 2.2uF as my favorite  

The LM386 leaves much place for experiments  :wink:

cu
Oliver

[lightningfingers]

instead of having the oscillation pot going from output to input, maybe try puting from output to pin 7, I got better oscillation control like that..

[Dragonfly]

instead of having the oscillation pot going from output to input, maybe try puting from output to pin 7, I got better oscillation control like that..

hmmm....pin 7, huh ? thanks for the tip....

andy

[j0shua]

here's a design for a fuzz pedal that i came up with..i havent built it yet (gotta get some 10k pots:) ), but could be pretty cool...and a pretty easy build too.  anyway, i was hoping you guys could look it over and see if you can identify any "trouble spots".... once the design is finalized, i'll post the schematic in the "layouts forum"  

http://aronnelson.com/gallery/Dragonfly-FX-Schematics-%21/DRAGONFLY_FX_DEVILS_RIGHT_HAND?full=1

as always, suggestions and comments are ALWAYS welcome !

thanks in advance !

Andy

Hmmmm ya like to play whit LM386 to hehehehehe, Dragon you are using the Negative Imput , try also use the IC pin 3 (+) for imput and pin # 2 to ground , and the 10K resistor from battery to Fet , you can put a socket to try diferent resistors ( 7.5k ,10k, 12.5k, 15 k , and 8.2k )  ....

[j0shua]

damm my PC restart alone ......

hmmmm you can put 5K pot from IC Pins 1-8 ( dirt ) if you put more value , need to dicipate more heat from IC pin 7 , or use heatsink or thermal paste .... or Fan cooler

oh yeah the clasic mod ---> switching diodes Led's & Germanium

Btw Check the PM i send to you

[Dragonfly]

Hmmmm ya like to play whit LM386 to hehehehehe, Dragon you are using the Negative Imput , try also use the IC pin 3 (+) for imput and pin # 2 to ground ,

any particular advantage that you can think of for using the non-inverting input over the inverting input, or vice-versa ?

and the 10K resistor from battery to Fet , you can put a socket to try diferent resistors ( 7.5k ,10k, 12.5k, 15 k , and 8.2k )  ....

i'll probably just use a 20k trimmer on the test run, just to be able to dial it in a bit better

andy

[Dragonfly]

damm my PC restart alone ......

hmmmm you can put 5K pot from IC Pins 1-8 ( dirt ) if you put more value , need to dicipate more heat from IC pin 7 , or use heatsink or thermal paste .... or Fan cooler

i think i'll probably use a 1k in the tester...just to see where that gets me. i'd imagine that i'll get plenty of fuzz even without pins 1 and 8 connected, just from the shunted diodes...but it'd be nice to make the sound even "uglier"

oh yeah the clasic mod ---> switching diodes Led's & Germanium

i'll probably keep the pair of germs, but i'd considered having the 1N914 switchable to a LED .....

Btw Check the PM i send to you

i'll go check it in a few

thanks Joshua,
 Andy

[j0shua]

Pin 2 of LM 386 cool. when you shot the IC pin#2 whit the FET BLOW LIKE HELL hehe, ver good distortion , and you can change the taste by de 2M2 Resistor , if you use 4M7 can be a mess distortion! and the 120 Pf can up to 150 or 200 Pf to gain more fat sound!




cheers!