The first DIY Arduino i built at the beginning of last year was used a 74HC04 IC based on the layout from Tom Igoe
But recently, Iv been building Serial boards like the Severino (S3V3) that use RX and TX transistor assemblies over a IC.......and i was just wondering if someone could brake down the pros and cons of both set up?
well the IC is going to be faster, its less to wire (or wire wrong) and its cleaner looking
ps looks like you have the same telephone wire I do (least it looks like it, purple n white solid copper, with double insulation, yellow on the inside)
The IC-based scheme cheats and provides 0/5V when it should be providing at least -3/+3V on the transmit data lines.
The transistor based scheme "steals" negative voltage from the receive data line to be able to transmit "real" rs232 levels (assuming that it is provided with real rs232 levels.)
Both seem to work pretty well; I wouldn't worry about it. If you ARE worried about it, I'd use a board with a real 5V rs232 transceiver (max232 or equiv.) A couple such designs have appeared (and nkc sells kits/bare boards.)
The transistor approach lends itself to being "distributed" across a PCB; convenient because there isn't a lot of room on the Arduino form factor. IIRC, the max232 is rather expensive, adds a lot of components (IC plus 4 caps) and is annoying to try to route on a single sided PCB.
(I haven't actually experimented with the 7404-based version. You could do something similar with a simpler transistor circuit, I guess, or do interesting things with "tinylogic", but... As Osgeld implies, it's main feature seems to be that it goes together easily on a protoboard.)
I use a 04 based converter from my pc to my barebones, its made by modern device, and aside from the de9 connector, its smaller than a stick of gum (infact if it were abit smaller it would fit into a de9 housing)
Ive used the transistor based ones before, and its more to keep up with when putting it together and mine had issues at speeds higher than 14.4kbs, course that is somewhat dependent on which transistor you used
Thanks for braking that down for me guys, really apprechiated! 