PCB layout of BCD clock

hi
i build a bcd clock shown in the page
http://ourworld.compuserve.com/homepages/Bill_Bowden/clock.htm
and all the circuit works fine and now i want to build a PCB using
SMD components
so
1.What size of SMD component should i use?(like resistor
size,capacitor size, etc....)
2.What can i do if the lines(wires) are crossed each other on my PCB?


Thank you in Advance


Yosef

 

[Jasen Betts]

On 2009-01-17, josegidayfin@gmail.com <josegidayfin@gmail.com> wrote:

hi
i build a bcd clock shown in the page
http://ourworld.compuserve.com/homepages/Bill_Bowden/clock.htm
and all the circuit works fine and now i want to build a PCB using
SMD components
so
1.What size of SMD component should i use?(like resistor
size,capacitor size, etc....)

biggest ones easily available (easier to handle)

2.What can i do if the lines(wires) are crossed each other on my PCB?

put them under the component same as you do with thru-hole only on a
smaller scale.

 

[Randy Day]

In article <4df6d0ab-370f-4dd8-b431-
4887b4df537e@p2g2000prn.googlegroups.com>,
josegidayfin@gmail.com says...

hi
i build a bcd clock shown in the page
http://ourworld.compuserve.com/homepages/Bill_Bowden/clock.htm
and all the circuit works fine and now i want to build a PCB using
SMD components
so
1.What size of SMD component should i use?(like resistor
size,capacitor size, etc....)

For capacitors you can use the smallest physical
size that:
- has a high enough voltage rating
- is comfortable for you to work with

As to comfort, if you don't have a fine-tipped
controlled-heat soldering iron, you probably
won't see good results with anything smaller
that 1206. YMMV.

For SMD resistors, keep in mind that they have
very low wattage ratings (is it 1206 or 0603
that is 1/16th watt? I forget.). Except for
digital pullup resistors, you still have to
use the wattages specified in the schematic.

2.What can i do if the lines(wires) are crossed each other on my PCB?

The standard method is to use a 0 ohm SMD resistor
as a jumper.

HTH

 

[David L. Jones]

<josegidayfin@gmail.com> wrote in message
news:4df6d0ab-370f-4dd8-b431-4887b4df537e@p2g2000prn.googlegroups.com...

hi
i build a bcd clock shown in the page
http://ourworld.compuserve.com/homepages/Bill_Bowden/clock.htm
and all the circuit works fine and now i want to build a PCB using
SMD components
so
1.What size of SMD component should i use?(like resistor
size,capacitor size, etc....)

1206 would be best. The biggest commonly available SMD part.
0805 is next smallest and ok too for beginners to solder.
Use SO package SMD parts for the IC's

2.What can i do if the lines(wires) are crossed each other on my PCB?

Art of PCB design is choosing a layout which minimises (or even eliminates)
these "crossovers".
This is much harder on a single sided board, easier on a double sided board.
You can use 1206 "0 ohm" SMD jumper links if you do need to "crossover"
traces.
You can run the traces under 1206 components and through IC legs if you need
to, just like through-hole design.

Dave.

 

[JeffM]

josegiday...@gmail.com wrote:

and all the circuit works fine
and now i want to build a PCB using SMD components
so
1.What size of SMD component should i use?(like resistor
size,capacitor size, etc....)

Bigger is easier to handle and takes more abuse.

2.What can i do if the lines(wires) are crossed each other on my PCB?

Yosef

Zero-ohm resistors.

It doesn't sound like you have selected any software
(which makes this MUCH easier)
--nor does it appear that you have you read up on this.

http://groups.google.com/group/sci.electronics.design/browse_frm/thread/dc3c1272fe977f38/a6c3f9f678a407bd?q=My-PCB-Design-tutorial+several-*-universities-*-*-*-*-*-are-*-including-it-as-*-reference-material-*-*-*-*-*-*-*-*-*+zzz-zz+qq+*-major-*-PCB-*-package-*-*-included-it-in-their-Help-system
(25-page PDF)
I'm surprised David didn't point you to this in his post.

http://www.electricstuff.co.uk/pcbs.html

http://www.linuxjournal.com/article/8438
http://www.geda.seul.org/docs/current/tutorials/gsch2pcb/tutorial.html

http://www.fullnet.com/u/tomg/gooteepc.htm

http://cd.textfiles.com/hackersencyc/ETC/HARDWARE/PCBFAQ.TXT

http://www.pic101.com/pcb/index.html

http://www.geocities.com/pdmtr

....for a start.

 

[JeffM]

josegiday...@gmail.com wrote:

Yosef

It would be good if you made your responses *in the group*
NOT via private email.

If using Google Groups
http://www.google.com/search?q=cache:24d8KkORPR8J:www.williamtasso.com/words/what-is-usenet.asp+news.reader+ditch.the.google.groups.interface+What.is.Google.Groups+no.choice+before+archive+*.pre-dates.the.Internet+requirements.for.participating+access.to.a.news.server+*.*.two.weeks.postings&strip=1
instead of a proper Usenet newsreader
http://www.google.com/search?q=cache:nQjcXUKFOLoJ:en.wikipedia.org/wiki/Comparison_of_news_clients+*-Gravity+Free+GPL+Microsoft.Windows+501+501+*-Agent+Xnews+Pan+Thunderbird+Traditional.Newsreader+501+Combination+501+501+501+Cross-platform
click *Reply* and NOT *Reply to author*.

In addition, if, before posting to a group, you *sign up* for that
group
http://groups.google.com/groups/mysubs
and, *instead* of using an email address for a username,
you would use JUST A NAME--without a domain tacked on,
*THAT* won't be obfuscated by Google
and it will make it easier for others
(especially other Google Groupers).