[sdiy] elect caps vs. polyester caps

[harrybissell]

On Mar 24, 2006, at 4:58 PM, nate reeves wrote:

  Anyway, i have some 33nF poly caps from a friend but they look
odd....first, they go way close to the PCB and are
  sort of square and red.....

  also, they do not appear to have + or - sides, is this correct? 


Yes, that it correct.  The poly caps are not polarized.  You can put
them in facing either direction.

Note... in some rare cases there can be a slight difference, especially
in "wrap and fill" film capacitors... double especially in the clear
covered polystyrene caps.

One side of the foil is on the 'outside' of the cap. If this side is
tied
to ground or to the lower impedance in the circuit (opamp output) that
foil might act as a shield to lower noise pickup.

If the cap is not clear, though... it will be very hard to tell which
side is which... :^P

H^) harry