Author Topic: Cap polarity question  (Read 401 times)

Antonio1963

Cap polarity question
« on: April 24, 2019, 04:34:11 PM »
The 220nf cap above IC socket 1 looks like a ceramic cap. I have an electrolytic in .22uf which I believe is the same value. The problem is that this capacitor is polarized and Iím not sure which direction the negative should go or if I could use the polarized capacitor in the spot ?


Kevin Mitchell

Re: Cap polarity question
« Reply #1 on: April 24, 2019, 04:47:30 PM »
Short and sweet answer - it doesn't matter.

-KM

Antonio1963

Re: Cap polarity question
« Reply #2 on: April 24, 2019, 09:50:57 PM »
Great, I thought it would since it was polarized. Thanks for the help Kevin.

antonis

Re: Cap polarity question
« Reply #3 on: April 25, 2019, 06:24:48 AM »
Although I totally agree with Kevin, I'd sleep in politically correct peace with its positive leg at right side..  :icon_wink:
Can't follow your signature changes, Stephen..!!
but I like what follows:
"put the coffee down, Antonis, and nobody will get hurt."
"Arggg, Jim ...."

merlinb

Re: Cap polarity question
« Reply #4 on: April 25, 2019, 10:54:44 AM »
I have an electrolytic in .22uf
Are you sure it says .22uF and not 22uF? I've never seen such a tiny electrolytic cap...

duck_arse

Re: Cap polarity question
« Reply #5 on: April 25, 2019, 11:13:35 AM »
are we just waving our hands over the cap and saying doesn't matter? looks like a ceramic doesn't cut the mustard if it goes in backwards and the circuit won't go. show us the circuit diagram and we might be able to say.
"Decrease the bracken!" - Bobo Gargle

Antonio1963

Re: Cap polarity question
« Reply #6 on: April 25, 2019, 03:51:44 PM »
I have an electrolytic in .22uf
Are you sure it says .22uF and not 22uF? I've never seen such a tiny electrolytic cap...
Itís a 220nf ceramic cap.  I thought that I could substitute a .22uf electrolytic capacitor. Since I donít have a 220nf ceramic cap.

merlinb

Re: Cap polarity question
« Reply #7 on: April 26, 2019, 03:26:23 AM »
I thought that I could substitute a .22uf electrolytic capacitor.
I don't think they even manufacture .22 electrolytic caps... perhaps you have misread the label? Anyway it doesn't need to be 220nF; anything from 220nF up to 1uF will do.

Positive should be on the right hand side, since it goes to the same place as the 1uF cap nearby.

Schematic:
https://elektrotanya.com/mad_professor_snowwhite_autowah_guitar_effects_schematic.pdf/download.html

bluebunny

Re: Cap polarity question
« Reply #8 on: April 26, 2019, 03:35:05 AM »
looks like a ceramic cap

IvIark's layouts don't (generally) distinguish between different kinds of non-electrolytic caps.  You just get an anonymous brown blob.  Brown doesn't mean ceramic.  Any film cap would do nicely.
Ohm's Law - much like Coles Law, but with less cabbage...

Slowpoke101

Re: Cap polarity question
« Reply #9 on: April 26, 2019, 03:59:22 AM »
Merlin is correct with his advice on the polarity required. I even took a few voltage measurements from my board and that polarity is correct for an electrolytic capacitor in that position. The value is not really critical at all.

Why do you have 0.22uF electrolytics ? I thought I was the only person mad enough to actually have any (about 30 ) but my excuse is that they were used in some Motorola commercial 2-Way radios - needed to repair RSSI circuits at times.

« Last Edit: April 26, 2019, 04:19:08 AM by Slowpoke101 »
..

duck_arse

Re: Cap polarity question
« Reply #10 on: April 26, 2019, 10:51:14 AM »
Merlin is correct with his advice on the polarity required. I even took a few voltage measurements from my board and that polarity is correct for an electrolytic capacitor in that position. The value is not really critical at all.

Why do you have 0.22uF electrolytics ? I thought I was the only person mad enough to actually have any (about 30 ) but my excuse is that they were used in some Motorola commercial 2-Way radios - needed to repair RSSI circuits at times.

still in my drawer - 4 x 0u22 100V & 2 x 0u47 63V, from a failed teevee repair, turn of the century.
"Decrease the bracken!" - Bobo Gargle

Antonio1963

Re: Cap polarity question
« Reply #11 on: April 26, 2019, 11:20:42 AM »


This is the box with the caps.

anotherjim

Re: Cap polarity question
« Reply #12 on: April 26, 2019, 12:13:12 PM »
Electro cap values go down to at least 0.1uF. I suppose they were a viable choice for small size and voltage rating before film caps got good & cheap.
If it's the cap feeding the envelope sensitivity amp, it don't really have much voltage difference across it but might as well be the same way around as the cap going into the filter (C11). Mind you, for guitar, I don't think you'll hear much difference if the sub was a 100nF.

"Designing with PLLs in production circuits is reserved to those with the courage of the thoroughly uninformed."
Nuts & Volts
"Turtles have the short legs, not for the walking."
-Kenji "Damo" Suzuki

PRR

Re: Cap polarity question
« Reply #13 on: April 26, 2019, 04:08:44 PM »
> I don't think they even manufacture .22 electrolytic caps...

Mouser lists 30 in-stock products 0.1u and 0.22u, Aluminium Electrolytic Axial/Radial (with legs). 50V-200V. Generally thousands in stock. 10 cents to 40 cents; most under 25 cents. 0.22u 200V Nichicon High Temp just $0.25 (10c quan 100), 3k in stock.

nocentelli

Re: Cap polarity question
« Reply #14 on: April 26, 2019, 07:37:57 PM »
Are you sure it says .22uF and not 22uF? I've never seen such a tiny electrolytic cap...

I still have most of a bag of 0.1u electro's I bought in error a number years ago. Never any use, since 100n is so common I have dozens of poly box and ceramics in that value
« Last Edit: April 26, 2019, 07:41:54 PM by nocentelli »
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