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CMATMods - Black Plague
Posted: 20 Dec 2010, 17:21
by fret_burn
Re: CMATMods - Black Plague
Posted: 20 Dec 2010, 17:41
by jb351
Looks like a tweaked Rat.
Re: CMATMods - Black Plague
Posted: 20 Dec 2010, 20:57
by culturejam
Man, what a convoluted layout. But at least there are no jumpers on this one.
Yep, it's a Rat of some sort.
Re: CMATMods - Black Plague
Posted: 22 Dec 2010, 20:15
by Dingleberry
Hi.
Just spent about an hour comparing those gut pics to various RAT schematics floating on the net and found out that the Black Plague is actually an 1:1 copy of early version RAT + the option of different clippers.
There is the correct RAT schematic:
-T
Re: CMATMods - Black Plague
Posted: 22 Dec 2010, 20:40
by uncleboko
culturejam wrote:Man, what a convoluted layout. But at least there are no jumpers on this one.
Yep, it's a Rat of some sort.
What pray is the problem with jumpers???
Re: CMATMods - Black Plague
Posted: 22 Dec 2010, 20:49
by roseblood11
No real problem with jumpers,
but this pedal is another example of a self-appointed pedal guru who isn“t able to make a good layout for a small and well-known circuit like this. You could make a layout for a Rat on a single-sided board that is half as large as this one (or smaller), most likely without a jumper.
Re: CMATMods - Black Plague
Posted: 22 Dec 2010, 21:01
by Dingleberry
There is a blue line that seems to terminate under the diodes on the left... i can't see where it goes from there.
I think it'll have to go to the same point where the other ends of 1N4001 diodes will go=>
junction of 4u7 cap and filter pot.
Looks to me that the diode switch adds either one 4001 diode or back to back pair parallel with red leds.
Never seen that arrangement before but that is what I figured out from the pics.
-T
Re: CMATMods - Black Plague [traced]
Posted: 22 Dec 2010, 21:27
by Dingleberry
Just accidentally took a look at the Lovepedal Les Luis thread and noticed that there is same kind of diode clipping arrangement... initation? It's just made with 1N914's and BAT46 schottkys.
-T
Re: CMATMods - Black Plague
Posted: 22 Dec 2010, 21:42
by roseblood11
Dingleberry wrote:Just accidentally took a look at the Lovepedal Les Luis thread and noticed that there is same kind of diode clipping arrangement... initation? It's just made with 1N914's and BAT46 schottkys.
-T
So what? A clone that is cloned from another clone?

Re: CMATMods - Black Plague
Posted: 22 Dec 2010, 21:44
by culturejam
uncleboko wrote:What pray is the problem with jumpers???
On a one-sided PCB, there's nothing wrong with jumpers.
But if you have the luxury of having traces on both sides, there's no real need for a jumper. This is especially true for a circuit as simple as a Rat or Tubescreamer.
If you come to a situation, on a two-sided layout, in which a jumper that runs from one side of the board to the other is required, then the layout itself should be rearranged.
My comment was a reference the CMAT Signa Drive, which has a jumper wire on *both* sides of the PCB. There is absolutely no need for that...unless the PCB design was flawed and the wires were needed to make it work.
Either way, it's bad design. That doesn't mean it sounds bad, however. Just commentary from a guy who likes to do PCB layouts.

Re: CMATMods - Black Plague
Posted: 17 Sep 2011, 00:15
by mictester
I try to avoid double-sided board layouts (except for RF designs). With some work, and if you're prepared to accept a jumper or two, most circuits can be built single-sided. This has the advantage that it's easy for anyone to make the board - I saw some beautifully made PCBs last week, that had used bright pink nail varnish as the resist, painted on each board by hand! The builder then etched the boards in Ferric Chloride, and removed the resist with Acetone after the etching. He then drilled the component holes by hand, and each board is slightly unique. The guy doesn't claim any additional "Mojo" for this type of process - it's just that he's always done it that way!
Re: CMATMods - Black Plague
Posted: 17 Sep 2011, 18:03
by culturejam
Since mic bumped this oldie, I thought I'd clarify something:
culturejam wrote:Either way, it's bad design.
Using jumpers on a 2-sided layout is bad design. Unless it's so that you can use the same PCB for different circuits, or something utilitarian like that.