Overly complicated Filtering and Pol Protection?

[lars-musik]

I want to shrink my noise gate into a 1590a and try to save some PCB estate. I don't understand quite a lot on the decimator schematic found on Revolution Deux:



But the assembly in the lower left corner really baffles me:
Is this some kind of filtering/polarity protection thingy? If yes, wouldn't one diode suffice and couldn't be the parallel caps (410uF) be replaced by a single 470uF?

[bluebunny]

Not sure about the diode overkill, but I think the last three 100nF caps are intended as decoupling caps located close to each IC.

[duck_arse]

those diodes looks like a pair of braces (D1, D2) for when your belt (D14) has burst.

[ElectricDruid]

those diodes looks like a pair of braces (D1, D2) for when your belt (D14) has burst.

How much current can a 1N914 take anyway? If you're going to short out the power supply when the connections are reversed, it might be a better idea to put a current limiting resistor in series with the diode, no?

[digi2t]

Not sure about the diode overkill, but I think the last three 100nF caps are intended as decoupling caps located close to each IC.

Frostwave Resonator is set up like that too. It's bipolar powered, so there's two caps right next to each IC, one for each rail.

[garcho]

How much current can a 1N914 take anyway?

yeah, odd that it isn't a 1N400x. and it seems multi-cap PS filtering is usually a 100µF and 100nF ceramic disc, not a 10µF electro, correct?

[slacker]

Other versions of the schematic like this one https://guitar-gear.ru/forum/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=31065 don't have D1 and D2. I guess they're just an error on that schematic, they don't do anything useful.

[lars-musik]

Other versions of the schematic like this one https://guitar-gear.ru/forum/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=31065 don't have D1 and D2. I guess they're just an error on that schematic, they don't do anything useful.

Hi Ian,
that's a nice looking schematic. You think this one is correct? I have never seen this before!

[slacker]

Sorry I don't know, I just googled decimator schematics to see if any of them showed those two diodes connected differently.

[garcho]

Hi Ian,
that's a nice looking schematic.

and that schematic has a proper rectifier diode being used (FR207), as opposed to a switching diode (1N914)

[lars-musik]

I found another one that also differs from the other two. But tidy also. Especially the send/return op amp configurations look different.

http://www.efekty-diy.pl/pdf/Decimator%20G-String.pdf

Might I bring that to vote? Which schemtic would YOU think worth the effort?

[PRR]

A 1N914 can clamp a battery good enough that your pedal may not fry.

In this day of 1.6 Amp wall-supplies, a 1N914 is not even a joke.

There are better polarity protections.