Which cap? Pin 7 of the DB25 is GND so the curved part of the 1uF symbol is (-) and the bar is (+). If you're talking the caps for the charge pump on the Max233, the 233 has internal capacitors for the charge pump so no external caps are required. The datasheet is here: http://datasheets.maxim-ic.com/en/ds/MAX220-MAX249.pdf Rich Rich Cini Collector of classic computers Lead engineer, Altair32 Emulator Web site: http://highgate.comm.sfu.ca/~rcini/classiccmp/ Web site: http://www.altair32.com/ /***************************************************/ -----Original Message----- From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org] On Behalf Of Zane H. Healy Sent: Sunday, September 17, 2006 8:02 PM To: classiccmp at classiccmp.org Subject: Capacitor Placement I'm in the process of building a MAX233 Serial Interface for my C64, and have run into one bit of problem. Which way should the "+" side of the Cap I have go in the following circuit? http://www.petscii.com/telbbs/max233-interface.jpg Zane -- | Zane H. Healy | UNIX Systems Administrator | | healyzh at aracnet.com (primary) | OpenVMS Enthusiast | | MONK::HEALYZH (DECnet) | Classic Computer Collector | +----------------------------------+----------------------------+ | Empire of the Petal Throne and Traveller Role Playing, | | PDP-10 Emulation and Zane's Computer Museum. | | http://www.aracnet.com/~healyzh/ |

On 9/17/2006 at 5:02 PM Zane H. Healy wrote: Unless the fellow who drew the schematic is wrong, the + side goes to pin 2 on the User Port connector and the - side goes to ground. The curved side of a capacitor symbol specifies the - terminal. If it's a nonpolar cap, then two straight lines are commonly used. But since pin 2 appears to be +5, the schematic is correct in that respect. Cheers, Chuck

Zane, The plus side of the cap is to the left ( Vcc side ). The convention is ( on the cap symbol ) that the "straight" part of the cap is "+" for a polarized cap and the curved part is "-". On a non-polarized cap the curved part represents the outside foil or outside can of the cap and should always go to ground or the closest reference to ground ( sometimes chassis ground ). Hope this helps. Best regards, Steven