The Quackmire: A simpler vactrol LP envelope filter for 1590A

[Bigbadwolf68]

What ever happened to this thing? No schematic link now...

[thermionix]

[Bigbadwolf68]

That was quick!  My sincerest thanks!

[Marcos - Munky]

Do you happen to have the layout? I remember there was one on the original post.

[thermionix]

I got the schematic from the OP (change .org to .cc), I don't see a layout or any mention of one.

[rankot]

Do you happen to have the layout? I remember there was one on the original post.

I've designed this one, but it's still untested.
https://docdro.id/IU4jLXx

Fits 1590A.

[forsakenrider]

I've designed this one, but it's still untested.
https://docdro.id/IU4jLXx

Fits 1590A.

Really nice layout there, what software do you use for those rad curvy traces?
If I can kick this cold I'll try and etch it out this weekend.

[rankot]

I use free a version of DipTrace, called PCB Creator. https://bayareacircuits.com/pcb-design-layout-software-for-custom-pcb/

But be aware that this PCB is untested, please print on paper and check if it fits enclosure first! Also have in mind that power section is a little bit altered, I have added 11V 3W Zener diode for overvoltage and polarity protection, together with 50-100mA PTC. If you don't need this, you can simply omit Zener diode and short PTC, or, in case you can't find such a diode, use 1N4007 instead.

[Marcos - Munky]

That's a nice layout!

[rankot]

Thanks!

[pinkjimiphoton]

I get "internal server error" when I try to download the circuit???

Downloaded OK today - how strange!!

no schematic link even visible, here

[thermionix]

no schematic link even visible, here

Quote the OP, rat f the postimg url from that, change .org to .cc

[Marcos - Munky]

Quote the OP, rat f the postimg url from that, change .org to .cc

Nice!

I remember there was a layout, but it wasn't on the 1st post:

[Fancy Lime]

Hi there!

Great to see people still being interested in this little thing.

@rankot
Nice PCB layout indeed! Thanks!

I checked it by retracing the schematic from your PCB and arrived at (almost) the original schematic plus the switching and indicator LED incl. series resistors and a 10µF cap. I'm not sure what the 10µ cap does for the indicator. Save the LED from power supply surges upon power-up? Anyway, it can't hurt. Other than that, only the series diode and resistor in the power supply filter were changed from 1n5817 to BAT85 and 47R to 15R respectively. Neither of these changes should affect the sound or operation of the device, use what you have. The only slight "mistake" I found was that the contact pads on the diodes and polarized caps are a bit confusing. Diodes have a square pad on the minus side and round on the plus side in the layout. For electrolytic caps it is the other way round. I'm not sure if that is some sort of weird convention I am unaware of, may well be. Just be careful and double check the orientations of polar devices when building this. Also: be aware that this is a tight layout. You may need to get particularly small varieties for the large value film caps. Greenies or orange drops or similar will probably not fit, the boxed KEMET caps (the beige ones) should fit, I think. Someone will have to try, I suppose...

EDIT: The original schematic had a trimmer to set the output volume, Rankos PCB has set that fix to max with a 100k resistor, which is probably what 95% of the people want 95% of the time anyway. And one more thing: If you put a switch instead of the time cap C10 that lets you choose between different size caps (1µ, 2µ2, 4µ7, 10µ, 22µ all sound nicely different) you get a much more variable pedal but it will be extremely awkward to put that in a 1590A. The next best thing is to socket this cap and try which value you like best.

Cheers and a happy 2019 to all,
Andy

[rankot]

I'll try this pretty soon, expecting PCB to arrive

LED and electrolytic cap pads are confusing, but that's how they are in this application I use.

10uF cap on LED is to avoid popping.

Once I verify this layout, I will release PDF with PCB.

[Kipper4]

"10uF cap on LED is to avoid popping."

What. Wait. Where.
On the bypass? Ala dead astronaught ?

[rankot]

http://www.muzique.com/lab/led.htm

I use the second circuit from this page.

[Kipper4]

Gottya. I was worried you were hanging it on the vactrol led. Phew.
I have used a // small cap before now with the vactrol led. Can't remember why. Something like 100-500pf

[rankot]

Parallel with vactrol LED? Maybe to reduce some flutter?

[Kipper4]

My memory aint what it used to be. Maybe......