Outer Foil on coupling caps: here's a No-Scope way to find it
Mar 5, 2023 0:04:54 GMT -5
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Post by Peegoo 🏁 on Mar 5, 2023 0:04:54 GMT -5
Installing non-polarized caps the correct way, with the outer foil on the signal-source side of the cap, makes for quieter operation. You can check this using a scope.
If you have no scope, you can make a little device that plugs into a guitar amp and see which side of the cap has the quieter lead. That's the signal source (outer foil) side. Used to be, all caps were marked with the outer foil side. Today, some are...but they still goof it up and sometimes are improperly marked. It's good practice to check it. The amp will hum more on one of the cap's leads; the other lead will be quieter.
This little box is something I came up with in a discussion on another guitar board. It uses a jack, a 3-way Tele switch, and two binding posts mounted in a small plastic project box. For years, amp builders have done this with just a jack and two alligator clips, but you have to unclip the cap and flip it which makes the amp bark at you, and it's fiddly.
This simplifies things because you leave the cap connected and flip the switch from one side to the other to find the quiet lead. And because the Tele switch behaves as a make-before-break switch here, the amp does not bang and pop. It's quiet. Leave the switch in the middle position when connecting and disconnecting a cap to keep the amp quiet.
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If you want to use an import switch like I did, here's the diagram:
Here's the one I built.
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If you have no scope, you can make a little device that plugs into a guitar amp and see which side of the cap has the quieter lead. That's the signal source (outer foil) side. Used to be, all caps were marked with the outer foil side. Today, some are...but they still goof it up and sometimes are improperly marked. It's good practice to check it. The amp will hum more on one of the cap's leads; the other lead will be quieter.
This little box is something I came up with in a discussion on another guitar board. It uses a jack, a 3-way Tele switch, and two binding posts mounted in a small plastic project box. For years, amp builders have done this with just a jack and two alligator clips, but you have to unclip the cap and flip it which makes the amp bark at you, and it's fiddly.
This simplifies things because you leave the cap connected and flip the switch from one side to the other to find the quiet lead. And because the Tele switch behaves as a make-before-break switch here, the amp does not bang and pop. It's quiet. Leave the switch in the middle position when connecting and disconnecting a cap to keep the amp quiet.
If you want to use an import switch like I did, here's the diagram:
Here's the one I built.
