https://effectslayouts.blogspot.com/2015/09/angry-beard-iii.html
I think this is the schematic for it: http://guitaristech-schematics.blogspot.ru/2010/11/angry-beard-iii-electric-guitar-effect.html
I've built it on an etched board yesterday and it doesn't work. Maybe you guys can suggest me something before I start tracing and breadboarding it.
I socketed both the ic and the transistor. I used a tl071 and various soviet germanium pnp eg: MP39.
I do get some crackling when I insert or remove the transistor.
My volatges are the following
battery: 8.60
+9: 8.08
ic pin1: 0.00
ic pin2: 6.11
ic pin3: 6.09
ic pin4: 0.00
ic pin5: 6.76
ic pin6: 7.96
ic pin7: 0.00
q1 e: 0.40
q1 b: 0.00 (shouldn't this be 1/2 supply voltage?)
q1 c: 0.40
Quoteic pin1: 0.00
ic pin2: 6.11
ic pin3: 6.09
ic pin4: 0.00
ic pin5: 6.76
ic pin6: 7.96
The first thing to fix is your pin 3 voltage. It should be VCC/2.
What's the voltage between the two 20k's? That should also be VCC/2.
If not check around that part of the ckt.
it seems to me that the transistor has no DC bias, so the base should be ..... erm ..... pnp, germanium, nope, too confusing for me.
> q1 b: 0.00 (shouldn't this be 1/2 supply voltage?)
Should be full supply voltage.
> it seems to me that the transistor has no DC bias
It is not even the right supply polarity for a "transistor amplifier", and the resistor values would make it an awful amplifier.
It's gotta be a diode sound-mangler. Draw-in the diodes explicitly. I suspect the 100K and Emitter do little or nothing. So the B-C junction can be any Ge diode or half-dead Ge transistor.
(https://s33.postimg.org/4wa9si13v/Angry_Beard.gif) (https://postimg.org/image/4wa9si13v/)
Quote's gotta be a diode sound-mangler.
Probably, the connection is even the wrong way for a PNP. Maybe used as diodes.
One site says uses PNP or NPN.
The output cap looks the wrong way around for the PNP case.
FYI: Initially I though this was an old commercial effect but it might actually come from the DIY scene.
I found this schematic, which as some notes,
(http://www.montagar.com/~patj/angrybd3.gif)
It has Jamie Heilman's name on it. A guy who had a small site with schematics and stuff around 2000.
(Maybe called Leper's Effects.) The file date I have says 1995!.
However, it looks like a schematic from RG.
I indeed put a wrong resistor in the 20k/20k divider (one was a 2k). However, it still isn't working yet.
Also, I screwed up the measurements a bit last time, the IC has 8 pins, not 7 :icon_surprised:
Here's a fresh a and correct version:
battery: 8.47
+9:7.90
ic pin1: 0.00
ic pin2: 3.99
ic pin3: 3.62
ic pin4: 0.00
ic pin5: 0.00
ic pin6: 3.96
ic pin7: 8.18
ic pin8: 0.00
q1 e: 0.40
q1 b: 0.00
q1 c: 0.40
Also I noticed that all transistor pins measure as short with continuity meter when it's powered up. :icon_eek:
Quote from: Rob Strand on December 17, 2017, 07:59:09 PM
FYI: Initially I though this was an old commercial effect but it might actually come from the DIY scene.
I found this schematic, which as some notes,
(http://www.montagar.com/~patj/angrybd3.gif)
It has Jamie Heilman's name on it. A guy who had a small site with schematics and stuff around 2000.
(Maybe called Leper's Effects.) The file date I have says 1995!.
However, it looks like a schematic from RG.
I have a directory where I must have downloaded all of the Leper's Schematics many years ago, and the text index file has a date of 1995 and thanks R.G. for help in drawing them, so your instinct is dead-on. They were drawn in Xfig. That was probably about the first repository of effect schematics on the www.
QuoteI have a directory where I must have downloaded all of the Leper's Schematics many years ago, and the text index file has a date of 1995 and thanks R.G. for help in drawing them, so your instinct is dead-on. They were drawn in Xfig. That was probably about the first repository of effect schematics on the www.
Interesting, thanks for chasing that up.
Maybe RG can shed some light.
Quotebattery: 8.47
+9:7.90
ic pin1: 0.00
ic pin2: 3.99
ic pin3: 3.62
ic pin4: 0.00
ic pin5: 0.00
ic pin6: 3.96
ic pin7: 8.18
ic pin8: 0.00
Have you tried adding the small cap across the 1M feedback resistor?
It could be oscillating.
Pin 7 different from the +9V looks a bit weird.
Quoteq1 e: 0.40
q1 b: 0.00
q1 c: 0.40
Also I noticed that all transistor pins measure as short with continuity meter when it's powered up
Are you using a PNP?
If yes then those measurements do look suspect.
Can you pull it out and check the transistor is OK?
One thing you could do is temporarily remove the transistor and wire the opamp via a cap to the output.
That will at least let you know the opamp is working.
Watch out it might be loud!
Takes me forever to debug anything.
Just checked the voltages again. Pin7 and +9 are at the same V.
Here's the transistor I used:
(https://s10.postimg.org/41gws5tth/78381c4c-0a82-43ea-9b47-37e98dad74df.jpg) (https://postimg.org/image/41gws5tth/)
It seems to work very well at after the opamp's output cap.