Crowther Audio - Hot Cake Overdrive  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
User avatar
obbarius
Information
Posts: 8
Joined: 20 Apr 2021, 03:12
Been thanked: 1 time

Post by obbarius »

Nocentelli wrote: 12 Jun 2021, 13:00
obbarius wrote: 12 Jun 2021, 09:43
Ok. I don't want everything served to me on a platter, but as a beginner, how do i go about checking voltages in the circuit? Is there a good way....
use a multimeter set for dc voltage up to 20v, put the black/negative lead on circuit's ground and touch the red probe to the +9v supply rail (with the circuit connected to the power supply/battery), note down the voltage and then touch each opamp pin in turn with the red probe tip (black probe always connected to ground as the reference point), noting their voltages.
obbarius wrote: 12 Jun 2021, 09:43
I'm also interested in tips for mapping a schematic (like the ones in this thread) to a vero board or something similar. Is there a method, that's easier for beginners or is it simply a matter of trying to arrange everything connected in lines?
There isn't really a particular method, but trial and error experimentation in attempting to do a vero of a simple circuit will quickly show you a few rules, conventions etc. There is a guide at tagboardfx that |V|ark put together which is more like a description of the conventions/principles he tries to stick to in his layouts, then a walk-through of him drawing up a layout for a circuit explaining a why he's done what he's done at each step:


http://tagboardeffects.blogspot.com/201 ... e.html?m=0
I could have been more precise when asking about how to check voltages. I was uncertain about how to figure out, what the voltages should be - not so much checking what they are. I guess there's no way around going through the circuit and calculating voltages based on resistances, diodes etc.

Found the guide on tagboardfx (http://tagboardeffects.blogspot.com/201 ... guide.html if anyone else is wondering). It looks good - i'll work my way through it later.

First time i noticed it was Mark and not ivlark too:)


Thanks so much for all the help.

User avatar
Nocentelli
Tube Twister
Information
Posts: 2222
Joined: 09 Apr 2009, 07:06
Location: Leeds, UK
Has thanked: 1152 times
Been thanked: 954 times

Post by Nocentelli »

you are checking for +9v (or whatever the supply voltage is after any diode drop/series resistance in the power supply) on pin 7, 0v on pin 4 and *very roughly* half supply on the both inputs and the output. You can post them here for analysis or search Google - Someone else is bound to have measured a hotcake's voltages before, even if if not the exact same model, e.g.
_20210614_075157.JPG
IC (TL071)
Pin 1: 0.13v
Pin 2: 4.38v
Pin 3: 2.12v
Pin 4: 0.00v
Pin 5: 0.13v
Pin 6: 4.38v
Pin 7: 8.09v
Pin 8: 0.00v
modman wrote: Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...

User avatar
obbarius
Information
Posts: 8
Joined: 20 Apr 2021, 03:12
Been thanked: 1 time

Post by obbarius »

Nocentelli wrote: 14 Jun 2021, 06:52 you are checking for +9v (or whatever the supply voltage is after any diode drop/series resistance in the power supply) on pin 7, 0v on pin 4 and *very roughly* half supply on the both inputs and the output. You can post them here for analysis or search Google - Someone else is bound to have measured a hotcake's voltages before, even if if not the exact same model, e.g.

_20210614_075157.JPG

IC (TL071)
Pin 1: 0.13v
Pin 2: 4.38v
Pin 3: 2.12v
Pin 4: 0.00v
Pin 5: 0.13v
Pin 6: 4.38v
Pin 7: 8.09v
Pin 8: 0.00v
Didn't even think to Google this, which is kind of embarrassing. I guess i just thought this was a little too specific, "geeky" and maybe too much of a beginners question, for someone to have documented it, but of course someone has (and of course Google knows).

Thank you! I now have plenty to dive into next time i have a couple of hours.

User avatar
freefrog
Information
Posts: 27
Joined: 08 Dec 2010, 19:44
Has thanked: 12 times
Been thanked: 13 times

Post by freefrog »

As the XLF mode in a Hot Cake clone didn't get much use here, I've modded it...

Without XLF, the coupling cap before the volume pot is now a 10nF. Cuts frequencies under 300hz. Makes the pedal tighter and therefore more versatile IME/IMHO. YMMV.

Have put a 150nF in series with a 47nF (=35.78nF in theory, 37nF measured with the two caps used).

This assembly can be put in parallel with the 10nF for the XLF mode, which is therefore equivalent to the "stock" mode now. :-P

Works well for me. Reason why I share the idea, FWIW.

Post Reply