Reverse polarity or positive ground the same?

Discussion in 'Burnt Fingers DIY Effects' started by bendeane, Apr 16, 2013.

  1. bendeane

    bendeane Tele-Meister

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    Are these just two ways of saying the same thing?

    Wondering if I can use a 1 spot with positive ground pedals using the reverse polarity plug, or the battery snap plug.

    My instincts tell me no because people are always saying you can't daisy chain them with negative ground pedals. But then I thought about the battery snap plug and if that would work.

    Any insights on why this wouldn't work would be great. Thanks.
     
  2. bendeane

    bendeane Tele-Meister

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    Looks like my next project will be a charge pump.
     
  3. Jack FFR1846

    Jack FFR1846 Tele-Afflicted

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    The answer is "it depends".

    Is the ground on the 1 spot really a ground or is it just designating that the barrel of the plug is that sense. So a negative ground has the barrel as negative......and a positive ground has the barrel as positive? (I don't know...I'm asking)

    The other thing I would be concerned about is isolation. My 1 spot is only a 2 prong plug, so I know from a safety standpoint, the output is completely isolated. But some computer adapters have a tie between the output ground and the safety input ground. That output ground could be positive or negative. So you have to follow that ground all around the entire circuit. Pedals, signal cables etc. That example is with a 3 prong plug, though.
     
  4. tjk3052

    tjk3052 Tele-Holic

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    I'm guessing that you're trying to power a pedal with PNP transistors? The easiest way to power them is by using the positive side of your power supply as the common, or ground connection. That's what is referred to as 'positive ground', which is the opposite, or 'reverse polarity' from most all other pedals.

    The plug polarity is different, and simply refers to which connection is the tip and which is the sleeve. The standard plug polarity is tip negative, and a reverse polarity adapter for a 1 Spot just reverses the that. How you connect the power internally from the power jack to the circuit determines whether or not you need it. If you connect the ground of your circuit to the sleeve connection, then you don't.

    If you plan on sharing, or daisy chaining, your 1 Spot, don't mix pedals that have negative ground with one that have a positive ground. You would be shorting out your power supply through your pedals, which is bad news.
     
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