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Projects => Beginner Project => Topic started by: bazzwazzle on August 28, 2004, 02:35:57 AM

Title: question relating adding distortion to the booster
Post by: bazzwazzle on August 28, 2004, 02:35:57 AM
Can i put the diodes right after the output cap, but before the 100K resistor?
Title: question relating adding distortion to the booster
Post by: remmelt on August 28, 2004, 01:24:05 PM
yeah, just put the diodes after the cap. see also here: http://www.diystompboxes.com/pedals/lava2.GIF. same basic idea.
Title: question relating adding distortion to the booster
Post by: kingnimrod on September 08, 2004, 11:47:08 PM
I get the concept, but am having a little trouble figuring out how to add the diodes with a DPDT switch into the circuit. Can someone post a diagram of how that works within the booster circuit? How would you add a second LED to that arrangement?

I have a micro dpdt toggle switch that I'd like to use for this.
Title: question relating adding distortion to the booster
Post by: aron on September 09, 2004, 03:32:30 PM
Can you explain a little more on what you want to do with the mini-DPDT?
Title: question relating adding distortion to the booster
Post by: kingnimrod on September 09, 2004, 04:29:36 PM
I have a feeling I am going to put this together the wrong way, so that's why I'm asking. Your build pictorial and the subsequent diagrams on wiring this stuff was incredibly helpful. Where I get confused is:

1) where exactly on the board to solder in a socket for these diodes

2) how to wire it into the rest of the circuit with a switch that turns the distortion off and on, plus an LED to indicate that distortion is engaged.

one other question - how varied will the distortion be if I try different diodes?

By the way - I just recently stumbled onto this site after looking for references to help me fix an old delay pedal, and now I've got the pedal-making bug. I just ordered a few of the 3pdt switches last night - can't wait to get them.
Title: question relating adding distortion to the booster
Post by: kingnimrod on September 09, 2004, 04:34:55 PM
oh yeah, forgot - the switch I want to control the distortion with is either a micro-toggle dpdt switch from radio shack, or a momentary stomp switch (maybe spdt??? dunno). Which would be better?
Title: question relating adding distortion to the booster
Post by: aron on September 09, 2004, 06:48:52 PM
see if this picture looks like what you imagined.

The DPDT is the mini-DPDT or you could use a DPST (ignore the other lugs).

(http://www.diystompboxes.com/beginner/distmod.gif)
Title: question relating adding distortion to the booster
Post by: kingnimrod on September 10, 2004, 09:23:28 AM
thanks - very helpful. However, I have a problem - The switch lights up the LED, but there is no distortion. The wiring looks OK, but I'm wondering if there's something wrong with the diodes. I twisted them together on one side and soldered - then plugged the loose ends into a 2-pin socket I put on the board.

Also, I have a question about the range control. turned all the way up, the range knob provides a slight treble boost, but it's very subtle. Is it supposed to be really noticeable? I would compare it to about 1/2 a turn on a guitar's tone knob. The .68uf capacitor is this really big yellow cylindrical mylar thing...
Title: question relating adding distortion to the booster
Post by: aron on September 10, 2004, 01:45:37 PM
I would imagine the range control to be subtle. Try different cap values to make more of a difference.

As for the diodes, do you have them "back to back" and reversed in polarity? What kind of diodes did you use?
Title: question relating adding distortion to the booster
Post by: kingnimrod on September 10, 2004, 06:16:42 PM
I wired the "top" of one to the "bottom" of the other -- twisted the ends together and soldered it - leaving two free posts to plug into the socket.

To tell the truth, I'm not sure what kind of diodes- i asked the guy at the electronics store to give me a couple that are good for distortion.

At this point, I'm probably going to go out and buy some more to see if that's the issue. These are so battered from pulling out and switching around so many times I may give up on them. Of course, maybe it's a wiring issue.

At any rate, the booster works and sounds cool - I will go out and get some more caps for the range control to see if I can get something more noticeable.

By the way - I am using the "cheapo" radio shack transistor in this circuit and it works fine.
Title: question relating adding distortion to the booster
Post by: aron on September 10, 2004, 07:44:22 PM
There should be a level change as you kick the diodes in. Does it drop in volume when you do that? If so, they are probably "working" just not distorting as much as you might want.
Title: question relating adding distortion to the booster
Post by: kingnimrod on September 10, 2004, 10:15:20 PM
There's no change to the signal at all - Is that more indicative that there's a wiring issue or a problem with the diodes?

I made another stop at the 'shack this evening for some stuff and picked up a 10 pack of silicon diodes and a 22uF cap to try on the range control.

can't wait to get that switch and get this thing boxed up!
Title: question relating adding distortion to the booster
Post by: kingnimrod on September 10, 2004, 10:24:54 PM
well, looks like I just answered my own question - stuck in 2 new diodes and still the same - looks like I need to desolder and clean up the wiring on the board and retry....
Title: question relating adding distortion to the booster
Post by: aron on September 10, 2004, 10:51:37 PM
Well one end of the pair of dioes should touch the "signal" line. The other end should touch ground. Once connected, you should hear a drop in signal volume.
Title: question relating adding distortion to the booster
Post by: bazzwazzle on September 11, 2004, 12:47:27 AM
so this means whenever i put the switch on the volume will become lower? Is there any way to fix that?
Title: question relating adding distortion to the booster
Post by: aron on September 13, 2004, 12:54:41 AM
Well, given that the diodes _will_ clamp down -there are  2 ways to "fix" this. Put a level recovery stage after the diode which will bring the volume back up when the diodes are kicked in, or put more diodes in series until you get a decent level you can live with and then pad the output when the diodes are not switched in.
Title: question relating adding distortion to the booster
Post by: bazzwazzle on September 13, 2004, 09:20:59 AM
Quote
pad the output when the diodes are not switched in.


What do you mean by this?
Title: question relating adding distortion to the booster
Post by: aron on September 13, 2004, 02:01:59 PM
You could switch in a pot when the diodes are not in. However, this is like disabling the boost function somewhat.
Title: question relating adding distortion to the booster
Post by: kingnimrod on September 14, 2004, 07:41:52 PM
okay, I still need help. I've desoldered and resoldered the distortion section in a couple of times, but there is still zero effect when I switch it on.

Please tell me if there's something wrong with how Im doing this part:

(http://www.sleepwalk.net/diodes.gif)


if i switch the diodes going the other way, still the same thing....


HELP!!!
Title: question relating adding distortion to the booster
Post by: aron on September 14, 2004, 08:08:31 PM
OK, looks correct now you do know that the diodes will only kick in when the drive is turned up enough to turn on the diodes right? That means you need to have the drive knob up enough OR use low threshold diodes such as germanium ones.
Title: question relating adding distortion to the booster
Post by: kingnimrod on September 14, 2004, 10:20:42 PM
booster all the way up, still no change in signal with the switch on. I even tried touching the ends of the diodes directly from the signal path to ground, and nothing....

If I use germanium diodes, do I just plug them in in place of these, or do I need to modify the circuit any further?
Title: question relating adding distortion to the booster
Post by: aron on September 14, 2004, 11:11:04 PM
Yep, just put germaniums where the Si ones were. Strange that you are not getting distortion.
Title: question relating adding distortion to the booster
Post by: kingnimrod on September 14, 2004, 11:18:12 PM
yeah, it's driving me crazy.

could it be possibly attributed to a faulty capacitor (not driving enough power to the diodes) - would the boost still work with a faulty cap???

I am really scratching my head here - The boost seems to work with no problems, but adding or taking away the diodes has no apparent effect on the signal. What should I be testing for to see what's wrong. Diodes test fine on the multimeter.
Title: question relating adding distortion to the booster
Post by: aron on September 15, 2004, 12:34:21 AM
How much does it boost without the diodes???? Maybe the diodes are kicking in but you can't hear it???
Title: question relating adding distortion to the booster
Post by: kingnimrod on September 15, 2004, 12:36:48 AM
boost is fairly pronounced - at the top end it breaks up/distorts a bit (this was so before I thought about adding the distortion). I guess if the diode distortion were weak, maybe it gets lost in there -- but when switched on, there is no loss of volume or tone suckage of any kind.
Title: question relating adding distortion to the booster
Post by: aron on September 15, 2004, 04:01:45 AM
Very strange. I guess put the drive so it's boosting but not distorting much. Then switch the diodes in and see if you get any distortion.

Just for fun, if you want to test the switch etc... Put a big cap in there instead of the diodes - say 22uF electro, plus side to the signal, neg to ground and when you switch it in, you should get a hugely muffled tone. This would indicate the switch works.
Title: question relating adding distortion to the booster
Post by: jayp5150 on September 20, 2004, 06:24:15 PM
king, did you ever get this to work for you?  I just built it the other day, and I think I see your problem.  Your drawing above seemed incorrect to me (sorry if I'm wrong).  

Shouldn't the diodes be connected on both ends, making them parallel?  Then you would connect one side to the signal, and the other to ground.  This creates a little "loop" with your diodes--each one will have one end to signal, one to ground (and they will be flipped from each other like you have).

That should work.  That's how I did mine, only I used four (2 on each side) to be less distorted and louder.  I also wired in one of Jack Orman's saturation controls, but this requires its own dpdt toggle to bypass--which I'm fixing tonight (I orignally had a spdt, but it did not cut it out of the signal all the way).

Hope that helps.
Title: question relating adding distortion to the booster
Post by: aron on September 20, 2004, 07:09:13 PM
You are RIGHT! I kept looking at his picture but never noticed!!!!

It should clip - but only one side of the waveform.

Here's how the diodes should be connected. TOP LINE is signal, bottom is ground.

(http://www.diystompboxes.com/pedals/2diodes.GIF)
Title: Re: question relating adding distortion to the booster
Post by: micro on August 19, 2007, 09:42:06 PM
I too am trying to add diodes to create a distortion but Im totally lost on their placement. Does anyone have a picture of what they should look like on an actual board.
Unfortunatley Aron's schem pic is Greek to me!  ???

So if they connect in a loop to each  other, which side goes to ground and which goes to signal out?
Title: Re: question relating adding distortion to the booster
Post by: jayp5150 on August 20, 2007, 09:01:19 AM
They would literally look just like the schem that Aron posted. The signal doesn't pass through the diodes, they are bleeding some signal off to ground.

(http://www.diystompboxes.com/pedals/2diodes.GIF)

OK, in the above pic, as Aron stated, the top line is the signal out. To the left would be the signal coming from the circuit directly the output cap, and to the right would be the signal out to the jack, directly before the resistor to ground.

The bottom part is ground.

The line on the diode symbol in the schematic is the same as the line on the actual diode. Connect one diode with the line toward the signal, and the opposite side to ground, then connect the other diode exactly the opposite way.

I'm sorry, I can't think of another way to really explain it. Also, you'll really want to start trying to "get" schematics. I still can't tell exactly what the electric current is doing by looking at a schem, but you need to know what the parts are, and how to make the connections off of just a schem. Basically, you can look at most simple schems, and lay the parts out on perf almost exactly like they are on the schem.

Keep at it, let us know that it turns out.
Title: Re: question relating adding distortion to the booster
Post by: micro on August 20, 2007, 01:36:35 PM
jayp5150,

   Thanks, actually you made it very clear to me. I agree, I do need to learn more about schems.
 Ill let you know how it turns out. Thanks alot!
Title: Re: question relating adding distortion to the booster
Post by: jayp5150 on August 20, 2007, 03:15:01 PM
No problem. I love when I'm actually able to help a fellow addict lol. I don't get a lot of time to devote to this anymore, so I'm still on the lower rungs of electronic knowledge.  :)