Post your questions about the build here 10/5/03

[les_chupacabra]

Someone asked something about holding down the circuit board while you're soldering.  The handful of times I've built stuff (modular synth modules) I just had the board laid on the kitchen counter but check out panavises if you want...

http://www.panavise.com/f/vises/vises_cbholders.html
http://www.panavise.com/f/vises/vises_combo.html

TechniTool is a good place for all sorts of electronics tools/accessories...

https://webvia.techni-tool.com/VIA5/index.jsp

[les_chupacabra]

Aron - Thanks alot for your effort in detailing this project.  I'm looking forward to building it myself in a couple weeks (I'm amp-less at the moment so there's no immediate rush).

I found Juan Carlos' LPB1 3D Layout/Schematic which looks very similar (schematically) very helpful as well - http://smallbox.zeonhost.com/

A couple questions...

What's setting the transistor bias here?  The 10k resistor above the transistor's collector?  Would replacing this w/ a trimpot and playing around w/ the resistance value be beneficial?  Could you describe biasing a transistor, why it is/isn't important, what you can expect if you're over/under biased?

Thanks!

John

[aron]

What's setting the transistor bias here? The 10k resistor above the transistor's collector? Would replacing this w/ a trimpot and playing around w/ the resistance value be beneficial?

The 10K, 360ohms and the 830K and 100K bias the transistor.

You can change the 830K/100K with a single 1M pot with one lug at ground, the other at 9V and the wiper to transistor base.

Biasing can affect the sound of the circuit - at more extreme misbiasings, the top or bottom of the waveform can get chopped off.

[les_chupacabra]

Sorry Aron - I was talking about the biasing in Gus' schematic not Juan's (although that's helpful too).

[aron]

In a similar way the 47K/10K sets the bias and connects to the base of the transistor.

[tonepoet]

Hi Aron,
     I did this a couple of days ago, but I got a kind of bad sound out of it. I took my time hooking up the board before I worried about any of the other things (pots, light, jacks, etc.). I triple checked my work, made sure that the soldering was clean, parts were in order and so on. Check! Then I began everything else, which wasn't really much of a problem given the diagrams that you had. It took me little while to find the right value of the resistor for the light to be bright. I got a Radio Shack light that has a small nut to screw it into the box and hold it securely, basically I had to us a 10k resistor. I finally got all of that working and hooked up a 500k linear pot and all the rest (leftover parts from something that I ordered from Small Bear but failed miserably) and was ready. Well, I plugged everything up and got a true bypass and the light worked and everything. But the sound is like a bad compressor, it seems to be barely on when I crank the volume, I have to really hit the guitar with some force to get a cruddy, semi-broken up sound that is not really a boost at all. Do you think that maybe I got the wrong kind of transistor? I can't think of anything else. I got something that said '222' on it, but I threw the box out. I switched the direction of the transistor and got nothing. Any suggestions what might be wrong?

[RJ]

I'm in the process of shoe-horning my booster circuit into a Hammond 1590B and I'm having some difficulties with metal parts of the board sometimes touching the sides or top of the box....is there a method of preventing this, like lining the inside of the box with something?

Also, depending on how I manage to make everything fit and not touch the box at all, sometimes the board and battery are sort of loose inside the enclosure and can bounce around a bit....what's a good way to secure the insides of the pedal?

Sorry, one final question...for my second project I'd like to build either a Big Muff or a Tyco Brahe (not positive how to spell that) octave pedal...would either one be considered easier than the other, for a total beginner?

Thanks in advance!  

[aron]

I'm in the process of shoe-horning my booster circuit into a Hammond 1590B and I'm having some difficulties with metal parts of the board sometimes touching the sides or top of the box....is there a method of preventing this, like lining the inside of the box with something?

Yes. Check out the GEO FAQ at the top. VERY informative. VELCRO works and will insulate and hold the board in the box!

Also, depending on how I manage to make everything fit and not touch the box at all, sometimes the board and battery are sort of loose inside the enclosure and can bounce around a bit....what's a good way to secure the insides of the pedal?

VELCRO can hold the board and a little bif of velcro can also secure the battery allowing it to be wedged in the box.

Sorry, one final question...for my second project I'd like to build either a Big Muff or a Tyco Brahe (not positive how to spell that) octave pedal...would either one be considered easier than the other, for a total beginner?

The Big Muff might be easier, only because it doesn't use a transformer like the Tyco does. Take it slow and anything will be possible!

[tonepoet]

Hi Aron,
I did this a couple of days ago, but I got a kind of bad sound out of it. I took my time hooking up the board before I worried about any of the other things (pots, light, jacks, etc.). I triple checked my work, made sure that the soldering was clean, parts were in order and so on. Check! Then I began everything else, which wasn't really much of a problem given the diagrams that you had. It took me little while to find the right value of the resistor for the light to be bright. I got a Radio Shack light that has a small nut to screw it into the box and hold it securely, basically I had to us a 10k resistor. I finally got all of that working and hooked up a 500k linear pot and all the rest (leftover parts from something that I ordered from Small Bear but failed miserably) and was ready. Well, I plugged everything up and got a true bypass and the light worked and everything. But the sound is like a bad compressor, it seems to be barely on when I crank the volume, I have to really hit the guitar with some force to get a cruddy, semi-broken up sound that is not really a boost at all. Do you think that maybe I got the wrong kind of transistor? I can't think of anything else. I got something that said '222' on it, but I threw the box out. I switched the direction of the transistor and got nothing. Any suggestions what might be wrong?

[aron]

OK, somehow the transistor is not biased correctly.

Measure your battery to make sure it has voltage.

Put the black lead of your meter on ground and touch each leg of the transistor and write down the voltage for each leg.

Measure the junction of the 10K and 47K resistors and tell me the voltage.

[tonepoet]

Hmmm, I'm not getting anything from measuring the legs of the transistor. I put the meter on 2v DC (is that correct, I've never used one before.). I put the black lead on ground and the red inside each of the socket holes. Nothing. I didn't get a reading on the bridge of the 10k and 47 resistors. I get a sound out of if, and the volume seems to work.

[aron]

Put it on the range where you can measure 10 volts and put the red on the positive of the battery and the black on the negative and see if it can read the battery voltage.

If you have an analog meter, consider a digital one.

[Lonestarjohnny]

Just finished building my Clean Boost on a Breadboard, Tried it with a NTE 490 and a 3604, Also tried a 2N2222, Liked all of them, this little Circuit kick's butt through my Super Reverb, All I can say is Hat's off to Aron,
This place is Like a Bananza, A Goldmine, A real Jewel of a forum, Sorry I hav'nt posted before but I have been so intent on reading all the posts on the forum that I almost forgot to interduce myself, I'm 57 years young, I've played guitar all my life, been married to the same Ol Gal for 40 year's, own to much Equipment to list here, I'm a Electronic's Tech in the Oil Drilling Bizz., I repair and mod amps when I'm home for a Hobbie, Now I can add Pedal Building to this,
My father was a Packerbell T.V, salesman/repairman, My Mom had her own CW band, I guess I can't help being Edicted,
Will be checkin in more often,
JD
San Antonio
TX.

Long Hair, Short Hair, What's the Diff once the Heads blowed off !

[aron]

Tried it with a NTE 490 and a 3604, Also tried a 2N2222, Liked all of them, this little Circuit kick's butt through my Super Reverb, All I can say is Hat's off to Aron,

GREAT! Well it's Gus Smalley's circuit! Thank you Gus! He generously allowed me to use his circuit as a beginner tool.

 

This place is Like a Bananza, A Goldmine, A real Jewel of a forum,

That's what I always wanted.  

Thanks for the kind words!

 

Sorry I hav'nt posted before but I have been so intent on reading all the posts on the forum that I almost forgot to interduce myself, I'm 57 years young, I've played guitar all my life, been married to the same Ol Gal for 40 year's,

Thanks for checking in JD. You sound like a happy guy! Congratulations!!!!!

Aron

[Triffid]

Hello aron... first of all, thank you for your outstanding site.  I have been tinkering with guitar electronics for a while but just recently have tried building my own pedals.  

I just finished putting together the beginner booster pedal here and I am getting a strange effect (the same as a previous poster I beleive).  The effect seems to be an "anit-boost", it only comes in when I hit the string hard, it seems to get pushed a little better if I have my strat switch in the second position (2 pups instead of 1?).  Reading through your previous posts I figured the following voltage readings would be helpfull.   I am using a 2n3904 npn transistor by the way... every thing else is as speced...

Transistor Collector: 8.44V
Transistor Base: 1.31V
Transistor Emmiter: 0.72V
47K, 10K junction: 1.71V

Hopefully you can give me some insite into what I did wrong from that info.  BTW... turning the pot seems to have very little effect... I can tell a slight difference, but not much.

Thanks again for your teachings and in advance for any help you can offer.

[Triffid]

Ok... I may have figured it out.  I simply pulling the tranny out, flipped it and stuck it back it.  The new measurements were...

Transistor Collector: 5.04
Transistor Base: 2.77
Transistor Emitter: 2.24
47K, 10K junction: 2.84

So I plugged it in... and boom... boost away.  It's late so I didn't turn it up too high (the wife is sleeping) but I can't wait to blast it in the morning.  The pot worked fine now too.  Now I need a cool box for it

Thanks again

[aron]

COOL!