Dirt/boost pedal not working as expected

[taviii]

Hi guys! I just finished a dirt/boost pedal based on the electra distortion.

It works as showed on this video when the boost section is on, but the clipping stage is just much less distorted than  what i expected to be.
Im using 2n3904 transistor and 1n34a diodes

[willienillie]

What Vf do you measure on those diodes?

[taviii]

What Vf do you measure on those diodes?

Sadly i don't have a multimeter. Electronics is a new world for myself. I do have 1n914 and 1n4001 diodes, maybe i could try those and see if they improve cliping.


Can anyone point me how can i add video/audio?

[antonis]

As far as your current diodes are indeed Ge, Si would do things worse..

What are the values of Collector, Emitter & Feedback resistors..??

[taviii]

As far as your current diodes are indeed Ge, Si would do things worse..

What are the values of Collector, Emitter & Feedback resistors..??

I will try to get a multimeter and check those values.

https://photos.app.goo.gl/gjbQ1HzGCHUZSYWB7
Im using the circuit in this video. Boost sounds just fine, but then i switch to diodes and you can hear that cliping is very poor, even at full volume. Lastly i add overdrive directly from the amp, which is more like the sound im trying to achieve.

[niektb]

@taviii: you happen to have a schematic for us?

[antonis]

What are the values of Collector, Emitter & Feedback resistors..??

I will try to get a multimeter and check those values.

Multimeter is always a good thing but you tell us you've just grasp 3 resistors while blindfolded..?? 

[taviii]

@taviii: you happen to have a schematic for us?

[taviii]

What are the values of Collector, Emitter & Feedback resistors..??

I will try to get a multimeter and check those values.

Multimeter is always a good thing but you tell us you've just grasp 3 resistors while blindfolded..?? 

Hey sorry i didn't understand the question at first time. I just uploaded the schematics with all the resistor values.

[antonis]

OK.. Start with 10k for R1..
(in case of severe misbias, let R1 as it is and shunt R2 with a 22μF cap..)

P.S.
Any estimation for signal source output impedance..??

[taviii]

Little update. After some tweaking i finally was able to make it work. Here are some pictures with a diy steel enclosure










The effect works as it should now. Only thing that i would love to know is if there is any way to reduce buzzing when the pedal is on. On bypass mode the amp is totally quiet but the effect gives some buzz. How can i improve this?

[antonis]

Try a Low-Pass filter between +9V and upper leg of R1..
(the greater the series resistor value the more effective the filtering - in the cost of voltage drop, which hardly should be 100mV on particular circuit for 100R resistor..)



P.S.
In case of low or none improvement, check for ground loops..

[taviii]

Try a Low-Pass filter between +9V and upper leg of R1..
(the greater the series resistor value the more effective the filtering - in the cost of voltage drop, which hardly should be 100mV on particular circuit for 100R resistor..)



P.S.
In case of low or none improvement, check for ground loops..

Thanks antonis i will try that and see how it goes, i just dont have any 470uf cap right now.

When i power the circuit with a battery it doesnt make any buzz, sounds great. Buzz appears only when i power it up from the dc jack. I only had metal jacks laying around so i insulated it from the case but is still touching somewhere. It works when i use a smaller conector which does not touch the sleeve of the jack.
If a plastic dc jack doesnt solve the buzz i will try the low pass filter

[ElectricDruid]

When i power the circuit with a battery it doesnt make any buzz, sounds great.

That's a dead giveaway for power supply noise. Antonis' filter should help a lot. Failing that, get a better regulated power supply for your pedals, and use that one to run the wifi box or something.

[taviii]

When i power the circuit with a battery it doesnt make any buzz, sounds great.

That's a dead giveaway for power supply noise. Antonis' filter should help a lot. Failing that, get a better regulated power supply for your pedals, and use that one to run the wifi box or something.

Yes I'm using a cheap transformer as power supply. I will try antonis filter.
The buzz or noise that I'm getting is very low actually. but it would be better if it were quiet as with battery's.

Thanks guys!

[ElectricDruid]

Definitely get a better power supply. I had one of those. The output voltage was nothing like what it said on the front, and it varied widely under load too. The 9V output gave between 14V and 11V. It was hopeless.

Maybe I still have it. I have a bag full of random adaptors. It might be in there, along with the lost Nokia phone chargers and adaptors for tape-based telephone answering machines and so on.