laying out pc board

[MrDEB]

have a pc board that I started laying out but its only a one sided board.
Is it better to put jumpers for power or signal traces?
see my schematic under eqlizer revised.
should have maybe put power traces first?
boards are 2oz boards
doing layout in expresspcb

 

[dknguyen]

I would put jumpers for low power traces over everything else (since you have decoupling capacitors anyways). It's less of a question of power vs signal as it is critical vs non-critical traces. It is better to jumper non-critical traces as opposed to critical traces (obviously!)

FOr power applications you want to give power traces top priority to minimize route lengths in order to reduce parasitics from creating voltages spikes and ringing that kill your circuit.

For signal applications you want to give priority to signal traces so maintain functionality of the circuit.

 

[Ambient]

I always route a fat power rail first as well. I have used short jumpers for power before, but always put a cap at each end of the traces.

 

[Pommie]

I try and keep power rails fat wherever possible.

Here's a board I hand routed Yesterday. The red traces will be jumpers.

Mike.

 

[Boncuk]

I try and keep power rails fat wherever possible.

Here's a board I hand routed Yesterday. The red traces will be jumpers.

Mike.

Hi Pommie,

English doesn't seem to be English. I always thought talking about jumpers the small things (two or three pins) with a 0.1inch pitch are jumpers. An ordinary wire bridge is also a jumper?

BTW, I missed the decoupling capacitors near both IC power pins.

 

[Torben]

Hi Pommie,

English doesn't seem to be English. I always thought talking about jumpers the small things (two or three pins) with a 0.1inch pitch are jumpers. An ordinary wire bridge is also a jumper?

BTW, I missed the decoupling capacitors near both IC power pins.

Hi Hans,

"Jumper" is kind of a generic term in English. When talking about, say, PC motherboards, a jumper is a small manual switch like you describe: some pins on the board and a small connector which fits over them. A piece of wire which jumps over traces or sections of a circuit can also be called a jumper. When talking about cars, booster cables are often referred to as jumper cables or just jumpers. Etc.

English is a mess. It's easy to learn, hard to learn well. After having learned another language well enough to get by in polite society, I have a new respect for those who learn English as well as you have.


Torben

 

[Pommie]

BTW, I missed the decoupling capacitors near both IC power pins.

They are indeed missing. This was a first draft to check my port selection lead to a viable (without vias ) single sided layout. I have since added a few more components and will probably etch it tomorrow.

You'll note the decoupler on the pic but not on the EEPROM. This is because the EEPROM is going to be switched so slowly that it shouldn't be a problem. Worse case I'll solder one solder side.

Mike.

 

[3v0]

A few tips.

On digital boards jumper power/gnd over multiple data traces. Better to use one jumper for the power/gnd then one jumper for each data line blocked by the power/gnd.

PICs do not always have port pins in order. Rather then use jumpers to sort them out you can ignore the order and use as few jumpers as possible. It makes the coding more difficult but you only have to write the code once. This does not work with all applications. Not for everyone.

Sometimes the best solution is to go with a DS board. They take a bit more time but is no more difficult to make then a SS board if you use the etcBottom-drill-etchTop method. If you are not careful you can still end up with a lot of vias to solder wires into.

When doing DS boards you can use resistor leads (or other axial parts) to move a signal between layers. Solder the resistor as normal then solder the leads where they enter the board on the top side too.

In Eagle you can make the board easier to solder by increasing the clearnce between different signals. I like to first layout the board with easy to achieve clearances. Then I increase the clearance in steps until I am satisfied or I can not get any more. There will be some areas that can not be increased much.

I wanted to make an easy to solder version of the Magic Switchboard. All the different signal clearances are 21 mils or better. The exception is the gaps on the solder jumpers. If there had been traces between IC or header pins they would be less then 21 mils too. Do the best you can with the parts you have.

Jumpers are in RED. Please do not try to etch a board from this image. I will post a pdf in the original thread after I build and test it.

**broken link removed**

 

[MrDEB]

decoupling caps on power pins

being this is and audio circuit using a duel power supply do I still need decoupling caps on the V+ and V- pins?
I am still trying to figure out current draw of circuit.
looking at data sheets some are easy = Icc but others are ??

 

[Boncuk]

Hi Pommie,

the design is perfect concerning the decoupling cap at the MCU. How about taking out the detour between pin5 (Sub-D-9pin connector) and pin15 of The MAX232? The trace goes down to intercept the wire bridge (excuse me: jumper), then bends up north-east again to finally go straigth down south to the MAX232. Give the power a better chance to get there. It might fall off track having to use sharp turns. Straighten the line directly west with absolutely no hazard for pin9.

Doing that and having me as an IC I'd give you a kiss.

Kind regards

Hans


Btw, I very often look at my layouts on screen and don't realize there are better ways to make them perfect. Printing them small corrections possible without a lot of work get obvious easily. Wasting 10 sheets of paper for a perfect layout doesn't bother me at all. Using both sides you can save 5 sheets. I also use additional enforcement traces at junctions. They take care of extra wire width and as much as possible of the copper remains on the board. Saves etching solution and helps to keep the environment a little bit cleaner.

 

[Boncuk]

Hi 3v0,

please excuse me. I have some trouble understanding what the word 'jumper' means. On your layout I could detect just two of them. There are two more red traces, but they are supposedly not called jumpers, are they?

May be I misunderstood the explanation of the term as given by Torben, but I assumed a jumper is something straight on a PCB.

How should a foreigner learn good English if everybody has his own interpretation of technical terms?

Kind regards

Hans

 

[Boncuk]

Hello Torben,

thank you for the flowers. However I think I still have to learn a lot of English, especially when studying some posts in this forum. It happens to me that I scratch my head thinking about the thread, which I am not able to understand a bit reading horrible English.

Sentences and words like 'I want 2 know' or '4 sale' have been developed by lazy Americans who forget to write their language correctly more and more. They are easy to understand by Germans who usually have a good portion of phantasy concerning foreign languages. It becomes more difficult reading e.g. "I +(picture of a screw)+ U".

As for the jumper (a universal term in English) the German language uses proper names describing exactly what the word means. So a jumper is a 'Steckbruecke' and and a jumper across a bunch of traces is a 'Drahtbruecke'. Anyway jumpers either used in a PC or on a PCB just jump over some obstructing traces or short something. A "Bruecke" (bridge) does the same.

Don't worry about jumpers. Thais use one single word for many applications. It is 'phid' which means turn off, switch off, close or simply 'shut up'.

Kind regards

Hans

 

[3v0]

EDIT: When I say wire I mean am talking about wire the you get off a spool. Sort of like metal string with or without insulation.

When I say trace I am talking about copper that was not etched from the PCB.

Hi 3v0,

please excuse me. I have some trouble understanding what the word 'jumper' means. On your layout I could detect just two of them. There are two more red traces, but they are supposedly not called jumpers, are they?

The RED lines are all jumpers. In this case wires soldered to the top side of the board.

May be I misunderstood the explanation of the term as given by Torben, but I assumed a jumper is something straight on a PCB.

He gave a very broad definition of jumper. In this case (and most PCB related) wires (not traces) used to jump over traces are jumpers. If you have two pins on a header and you connect them together with a shorting block that is often called a jumper too, but it may be best to think of it as a shorting block. In my layout there are 6 solder jumpers. These act like the shorting block but there are no pins. Just a small gap that you can bridge with solder.

How should a foreigner learn good English if everybody has his own interpretation of technical terms?

Hans

I recall taking undergrad physics from a grad student who command of english was very poor. The world is getting smaller and we all have to live with it

Ask as may questions as you need to.