LOG: Made a correction/modification Step 3 and added a picture step 5.
So many Arduino users have RBBBs(Really Bare Bones Board (Arduino)) or Anarduinos or Boarduinos that could use a USB interface to program and power them but don’t want to spend $15-20 for a USB BUB or FTDI cable. This Lazy Old Geek is one of them.
Theory: Most Arduino clones are programmed with a PC using a USB port. Theoretically, they could be programmed with an RS232 port but it is really hard to find a PC with RS232. Some Arduino clones come with a USB converter but most do not. Most require a TTL serial connection. TTL stands for Transistor-transistor-logic which basically means 0-5Vdc logic. So these Arduinos require a USB to TTL converter. One of the more common is the USB-BUB by Modern Devices:
I own one and like it but they’re costly.
So I saw these (see picture) USB to RS232 Serial DB9 Adapter cables on ebay for less than $2 so I bought one. Since I had three weeks to wait for it, I thought about and realized that it probably wouldn’t work as true RS232 has plus and minus 3-15 Vdc signals.
Read more: Arduino USB