Wednesday 10 April 2024

Death by Audio Germanium Filter

 A while ago. Chris Stelloh sent me a Death by Audio germanium Filter to trace. The trace went pretty smootly and I sent the schematic to Chris and he made a vero layout out of it. However, this circuit requires some transistor and diode picking to work as intended. See Chris's notes below...

 

My notes + warnings from my build attempts: PROCEED WITH CAUTION.

1) The transistors: DBA used MP10b NPN germanium transistors which have a common hfe range of 20-50. The lowest gain transistors I have on hand are MP35's around 40 hfe. And none of these worked properly. At lower settings, the gain was sputtery and sounded misbiased. I was able to get the circuit to work properly with some NPN Fairchild silicon dots from Small Bear that measure at 25 hfe.

2) The unknown silicon diodes on the mosfet gate: 1n4001-4007 worked quite well. I had my best sounding results with 8.2v Zener diodes. the 9v supply will cause any Zeners with lower than that rating to heat up and pop.
 
 
And here is layout with trimpots for the collectors solve the gating issue when the Gain control is turned counter clockwise. I also ditched the internal trimpot in favour for an external volume control.
 

 

 

 


Tuesday 9 April 2024

Capitalist Death Cult No One Wants To Work Anymore

 Taking a break from the Madbean bonanza since Chris Stelloh sent a layout and a schematic of one his creations. Some words from the man himself: And yes, this layout is verified.

Here is something I came up with recently that shakes the pillars of heaven, via WAY TOO MANY cuts and jumpers.

It is essentially the modded fuzz face circuit from the Apocalypse Audio H Fuzz with an input buffer (sacrelige, I know), followed by a 5 band gyrator EQ. I used the values from the Dunwich Left Hand Path modded HM-2 and added a 5th lower gyrator that centers at 60Hz, so that bassists can bring the buzzsaw, too. The gain squeals when maxed, but the gate will still clamp down on it nicely. The d311 germanium diode is most likely not necessary. Anything with a .3v volt drop will probably do the job. The 50k trimmer sets the treble content from the fuzz before it hits the EQ stage and sounds best (to me) at about 1 o'clock, but to each their own. This WILL fit in a 1590bb, but just barely!
 
 

 

 

Friday 5 April 2024

Madbean Stank

 Madbean pedals was a great resource and very educational when I started out with DIY circuits. The archives with old projects is quite impressive. So the next coming days you'll see some Madbean content (some well-known, some obscure). Let's start with something simple...STANK! 

The schematic can be downloaded at Madbean Archives page. 




Sunday 31 March 2024

EarthQuaker Devices Organizer

 Chris just sent me an another Spin FV-1 based layout. And he verified it.

"This is a layout for the Earthquaker Organizer Polyphonic Organ Emulator that I drew up using the Pedalpcb schematic. Two things about this layout (which is verified - I have all ready built it):
1) it addresses the volume drop issue that was common in early traces of this circuit. The pedalpcb board now has a 20k trimpot to solve this, which I have simply converted to the 20k resistor that is on pins 13 and 14 of the quad op amp.
2) you will need some supplies - an FV adapter and the EEPROM with the algorithm - which I would recommend getting from pedalpcb. PCB Guitar Mania makes a clone of this but I did not see a listing on their site for an algorithm chip or an SMD adapter. The FV-1 adapter board that pedalpcb makes is quite easy to use and I would also recommend watching DK Pedals' tutorial on YouTube for soldering the FV-1, as it was very helpful to me. The EEPROM algorithm chip is available for about $6.00 and if you search 'Organ Donor EEPROM' you will find it. It is not listed on the regular EEPROM menu. Also - 2x14 rows of pin headers will be needed to go between the adapter board and your vero."


 

Thursday 28 March 2024

Frost Giant Electronics Black Gold

 Traced by moushh.

This thing looks quite wild. With the gain control set at minimum, you have the stock Acapulco Gold gain setting. Turn it up and you'll have much way much more gain avaiable... The Bright control is an welcome addition, a simple adjustable low pass filter.