Dance Electra Debugging

[DaKurt]

So, I finally plugged everything in, and first of all I heard a littlebit radio
And there was much noise. Then when I tried to play through it was really quiet, and I had to turn up the amp to hear anything. And then it wasn't distorted at all. It was just clean. Do you know why that could be?

again the schematic is here:
http://www.geocities.com/CollegePark/Library/1355/electra.gif
(copy & paste)


Is it the transistor, the diodes...?
Or is it because of the battery connection?
I don't have a on off button. But let me tell. I have my battery-connection thing with red and black lines. Then I connected the red one to the 9v power in. The black one to the jack. And there is no other connection from this jack-battery connection to the pedal. Is that normal, that this stereo-jack connection ends there?

[DaKurt]

so again, my main-problem is not the noise. It's why it does not distort... :/

[smoguzbenjamin]

Mate, the black battery connection goes to the ckt ground. No electrons can flow to & from the battery otherwise

[DaKurt]

so 1 of the 3 connections at the jack is then free ? or what do I have to put there?

[smoguzbenjamin]

Unless you want to switch power on/off with the input jack, then the ring lug goes to ground and the sleeve lug goes to the batterys black lead. the tip obviously goes to the circuit input

[DaKurt]

so then it's right like I did (I just told it wrong, because I'm German, and it's pretty hard to explain technical things )...what part of this schematic does the distortion?! What should I check again. The signal goes through the pedal without being changed (it only turns down the volume)!

[DaKurt]

Could it be because of:

1) a wrong / damaged diode?
2) wrong connected transistor (though I don't think so)
3) I didn't use a audio Pot, I used a normal one
4) someting else

[smoguzbenjamin]

Ich spreche auch ein wenig Deutsch (was that right? :? )... If you type it in simple german I'll get it.

Diodes clip but they do decrease the output volume because part of the signal is being shunted to ground. That would explain the volume drop. Did you use the transistor that the schematic specifies? Also, be 400% sure of your transistor pinout.
You could also try lowering the value of the emitter transistor (690 ohm) for higher gain, but only if the transistor is oriented properly in the first place.

The distortion is created because the diodes clip the amplified signal. So tha transistor amplifies, and the diodes distort.
An audio pot or a linear pot doesn't matter much. It will just act a little different.

[DaKurt]

ah I'm sorry, it was the transistor

but it works fine now ... ah I'm so unbeliebably(sp?) happy ...


one question. Do you know where I can get the stomp switched (dpdt) here in Germany? And what das DPDT mean, so that I can explain them what I want.

[DaKurt]

ah it's a great feeling, to build the first pedal in just 4-5 hours ...

thx for the help

[smoguzbenjamin]

Double Pole Double Throw.

It's 2 'poles' which can then be connected with two 'throws'. A DPDT acts as 2 switches operated by the same action, and have nothing to do with eachother mechanically.

think of it this way:

Code Select Expand

0|0 <---Throw 1
0|0 <---Pole
0|0 <---Throw 2

In state one, the pole is connected to Throw 1, on both sides of the switch.
In state 2 (you're guessing what I'm about to say ) the pole is connected to Throw 2 on both sides of the switch

[DaKurt]

hmmm, could you perhaps tell me some common "names" of these DPDTs, in order that I can search them in google and see which shops do sell them. For Example the alpha 107 ... and so on

[smoguzbenjamin]

Well I buy 'em locally, I just go to the shop and ask for a DPDT footswitch So I can't help you there, sorry. :roll:

[DaKurt]

hmmm, k. I think the biggest electronic shop here in munich (conrad) doesn't have them. Do they really cost 10â,¬ or are there cheaper models. I mean, 10 or 12â,¬ are pretty much (more then the whole rest :/ )

[GuitarLord5000]

Y'know, after reading this post a few hours ago, I tried this circuit out.  The only differences are that I used a 2.1M resistor instead of a 2.2M (wired 2 1M and a 100K in series) and instead of the 690 ohm, I used a 1k, all due to lack of parts.  I got the same kinda problem you got.  Absolutely NO distortion.  I was thinking that maybe the 1K limits the circuit too much.  I'll keep trying a few different diodes in my sockets  :wink:  (i socket almost EVERYTHING now!) but if that dont work, and lowering the resistor value dont work, then i'll just have to chalk it up to bad luck!

[smoguzbenjamin]

The 2.2M resistor is biasing the transistor so that might be vital. It's completely wierd because last night I constructed this exact circuit on my breadboard, and I got a nice, if not gnarly distortion. I tried lowering the emittor resistor and that resulted in more gain. The only difference is that I used 1n4148 diodes, they seem to have a lower clipping threshold, the 1n4002 worked nicely too. :? Strange, guys. Try different pickup settings and make sure your guitar volume is full up, because mine cleaned up nicely with the volume knob.

[GuitarLord5000]

I'll go to the Shack tomorrow and get some of the specified diodes and socket them.  Im currently using scavenged generic diodes.    I'll also add another 100k resistor to my series chain to give me the 2.2M.  The weird thing is that I changed my tranny from a generic to the 2N3904 and got a slightly distorted sound.  I then removed the diodes from my sockets and.....still had a slightly distorted sound.  Kinda similar to Gus's NPN boost design.  The diodes had absolutely NO effect!  I mean, even if they werent the correct value diodes, I'd expect SOME sort of sound difference.  I dunno, maybe I'm wrong.  Any ideas?

[smoguzbenjamin]

You are driving the transistor at the top of it's amplification range, making it go into saturation, which creates clipping After that it doesn't ususally make a difference with the diodes, in my experience... :roll:

[DaKurt]

mine works fine now. It was just because of the transistor. I connected the emitter and collector wrong

[smoguzbenjamin]

Thought so. Gratuliere!

By the way, switches are very expensive. I pay E9,50 for one footswitch. Damn that really cuts into my wallet :?