reading schematics

[icefire]

hey, im completely new to electronics and would like to begin building some stomp boxes and amps.

i had just finished learning to apply ohms law to resistors etc and was feeling pretty pleased with myself, so i picked up my Electronics Projects for Musicians book and had a look at some of the schematics. that was fine, i could see 'yup, that's an integrated circuit, thats a 2 nano-farad capacitor' but when i compared the schematic to the author's pcb layout they looked NOTHING alike.

i'm wondering is layout all a matter of preference, and if one blindly followed a schematic
in a linear fashion, eg: lining all the parts up and connecting them with wire as it would appear on the schematic, would i get good results? is layout really a matter of preference?

also, i notice a little plus within a circle on the schematics, i'm assuming this is the symbol for the power supply input?

thank you for reading

[Enzo]

I don't know what schematic you are looking at, but yes, as a rule when you see a + in a circle and a "wire" going to it, it represents the + power supply.

Schematics show the electrical relationship between parts.  Wiring diagrams and layouts show the physical relationship between parts.  The schematic has no relation to how you lay the parts out.  SO unless you have a VERY simple little circuit, the layout won;t look like the schematic.

Layout isn't random, you want most times to keep the input and output circuits away from each other for example.

[J M Fahey]

Hi Icefly. I fully agree with Enzo and add: don´t get mistaken by comparing drawings (schematic vs. PCB) "geometrically" as in:  hey, i have a straight line here!!! ... i should find it there!!! ....  because it does not work that way. What lines indicate is an *electrical* connection; so if , for example, where there is a line (its does not matter whether its straight, curved, zig-zagging, whatever, only that it is uninterrupted/continuous) joining, say, pin 6 from one IC to pin 1, positive, from an electrolytic capacitor, be certain that on the PCB you´ll find the corresponding track joining those same pins, and so on.
Do it as an exercise and soon you´ll "see" the correspondence easily.
You *can* lay out a PCB almost exactly like the schematic,it may work,  but most certainly you´ll have a very poor layout.

[icefire]

just had an eureka moment. so it doesn't matter if the schematic says it's beside another component and i, for the sake of tidiness, put it above as long as i have them connected in series as per the drawing?

thank you for your helpful replies!

*edit* i am now studying a VERY simple circuit. i did not think this would be important but u learn something new every day like

joe

[krayzie]

             Is there a diagram to know the schematic.


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[J M Fahey]

Sorry krayzie, your question is not clear. What do you want to do? Learn to "read" schematics? Bye.

[icefire]

well, krayzie as i am also a bit of a noob, i feel i can help. let's assume you will be working on a breadboard. there are 2 strips that run the length of the breadboard, the + and - busses. every line of the schematic that is connected to the +9v or similar power supply is connected to the + strip on the outside of the breadboard. anything that looks like this " ii> " goes to ground or the negative strip, which is the strip marked '-'.

first wire up everything that goes to the + and - busses, for example your battery and your op-amps. next you just connect everything else up with jumper wire as per your schematic. a good book to read would be 'electronic projects for dummies'. the 'for dummies books' are generally very good, and although some of the projects in the book are pretty unappealing, you will get a good sense of what goes where in a circuit.

hope this helps.

[joecool85]

             Is there a diagram to know the schematic.

This should get you started: http://library.thinkquest.org/10784/circuit_symbols.html