13 Replies Latest reply on Mar 8, 2019 4:24 PM by genebren

    Schematic

    idontunderstand

      im 71 years old and am experimenting with electronics. However as much as I try and study I am getting bogged down with schematics. I’m ok with simple circuits but as they grow I lose all direction. Can someone please colour code a large schematic so I can see where positive and negative are in conjunction with the components. I realise for your community this is obvious but for me quite confusing. I have watched countless videos on schematics and am being told you can build circuits just by following a schematic. However not for me.

      many thanks

      ROGER

        • Re: Schematic
          rachaelp

          Hi Roger,

           

          When you first start with electronics things which some people think are trivially obvious are not as a newbie, don't feel disheartened by this, it'll get easier with time, the key thing is to keep at it and, as you have done here, ask for help! Do you have an example of a schematic which you are struggling to understand? If you are looking at something really complex, maybe take a step back and look at some more straightforward designs first, then when you are comfortable with those, move on to the more complex.

           

          The good news is, you're in the right place to find people to help you learn, element14 is full of knowledgeable people who are willing to help people learn!

           

          Best Regards,

           

          Rachael

          6 of 6 people found this helpful
            • Re: Schematic
              idontunderstand

              Rachael

              I don’t have a specific schematic as I get lost with anything but the most basic circuits. I can build simple circuits and very much enjoy this, however anything more than lighting a LED I get very confused where positive ends and negative takes over when all the lines are joined and the same colour. I was thinking that if the schematic was colour coded it might help me understand when I am not understanding it.

              Many thanks

               

              Roger

              5 of 5 people found this helpful
            • Re: Schematic
              genebren

              Roger,

               

              The key to understanding electronics is to study the basic rules or laws to which all electronics must follow.  These laws (Ohm's law to start with) help you better understand the flow of electricity in a circuit.  These laws can help you transform larger, more complex circuits down into simpler and more understandable blocks.  Another useful learning method is to use a simulator to build and test circuits.  I use LTspice (free download).  In this simulator, you can easily model circuits and observe the voltages and currents, which will allow to reinforce your understanding of the laws and formulas.  Be patient, learn and repeat lessons to build your knowledge and of all things, remember to enjoy the process.  Find fun ways to try new things, like buying and building simple kits.  Experiment with these kits (either on a simulator or by physical modifications) to increase the knowledge.

               

              Have fun,

              Gene

              6 of 6 people found this helpful
              • Re: Schematic
                ralphjy

                Hi Roger,

                 

                Element14 has an excellent series on basic electronics called the Learning Circuit.  Have you looked at that? The Learning Circuit

                 

                It really helps to understand the basic circuit elements before you try to tackle schematics. 

                 

                 

                Ralph

                6 of 6 people found this helpful
                • Re: Schematic
                  idontunderstand

                  Ralph

                  it appears no matter how many times I say it that no one is understanding that I really struggle understanding schematic drawings. I have watched many many schematic turorials and still don’t get it. I have also watched The Learning Circuit tutorials and still don’t get it.  I’m ok with basic schematics and can build simple one dimensional circuits but get confused when the circuits get larger. I can’t get my head around where positive ends and negative starts. I know this is really simple to you and must be frustrating that I don’t get it but that is how it is.

                  If only someone would be kind enough to colour code a schematic drawing to help me understand.

                   

                  Many thanks

                   

                  Roger

                    • Re: Schematic
                      shabaz

                      Is there an example of the type of color-code you mean?

                      I've tried in the past to color-code some wires, but I've only found it usable for very small circuits, such as this one:

                      It can sometimes look fine, but although there are three black lines at the bottom, they are actually separate wires that are not electrically connected, they are connected to MOSFETs. So the color code can get confusing too if done in this way (and there are not enough easy-to-identify shades for most circuits, to have one shade per net).

                      This circuit uses red to indicate positive, and the three black lines are 'kind of' negative, but they are all different negatives. The left black line is a permanent negative, and the other two are switched negatives. It would be hard to convey this meaning with separate colors, but can be explained in a text explanation of the circuit, or perhaps by recognizing the pattern of two MOSFETs and resistor as shown.

                       

                      I prefer when circuit diagrams look like this; here the section is identified, it is clear that it is the power supply sub-circuit that is part of a larger circuit, because it has its own box and title, within a larger schematic sheet. Do you mean this dashed box ought to be shaded in a single color, so that the sub-circuit is identified by color?

                      4 of 4 people found this helpful
                      • Re: Schematic
                        ralphjy

                        Hi Roger,

                         

                        I think part of the problem is understanding precisely what you are asking for.  I know that might sound strange.  I'm not sure what you mean by "where positive ends and negative starts".  I think that we might be struggling with how to color code a schematic for you.

                         

                        I'm going to be offline for a while, but if you can explain exactly what you need,  I'm sure someone could help.  It really would be good if you could provide an example of a schematic you don't understand as a starting point.  And indicate how you would want color coding applied to that schematic.

                         

                        Ralph

                        2 of 2 people found this helpful
                      • Re: Schematic
                        shabaz

                        Hi Roger,

                         

                        In conjunction with all the other excellent techniques mentioned, familiarity over time will make you recognise portions because they will look like patterns you've seen before.

                        Unless it is a very poor quality schematic, most people will try to draw their schematics in some well-known styles.

                        This web link 101-200 electronic circuits is quite good, it has lots of small circuits to gain a quick appreciation of what types of circuits will achieve certain tasks.

                        There is also 1-100 electronic circuits and 100 IC circuits and 50 555 circuits, they are all useful.

                        So, for example, here are some random snippets from there:

                         

                         

                        At a glance, it is possible to tell this is a 'H-bridge' circuit, due to the shape looking like a H. It is used to switch power in either direction. It could have been drawn totally different, but people don't do that - they try to draw it in this style. It becomes an easy pattern to recognise in a larger circuit. Also without any labels, by convention it is possible to guess that the top line is a positive supply rail, and the lower is 0V. This convention wouldn't be assumed when constructing the circuit (since then precision about it is required), but it can be initially assumed when trying to guess what a schematic does.

                         

                        Even though this is just part of a circuit, it is instantly recognizable as something that will pulse and flash LEDs in a sequence. This is because the 555 is a well-known chip for generating a single or stream of pulses, and the 4017 is well-known to convert an input pulse stream into ten outputs in sequence.

                         

                         

                        The circuit above can be assumed to be some sort of amplifier, with two stages, since that's a normal use of a transistor. It look designed for amplifying AC signals, since there are capacitors on the input and output that would block DC.

                         

                        Anyway, these are just some examples, there are many more sub-circuits like these to explore.

                        5 of 5 people found this helpful
                        • Re: Schematic
                          luislabmo

                          Hello Roger,

                           

                          I think these links may be very, very useful for you:

                           

                          How to Read a Schematic - Sparkfun

                          Skill Builder: Reading Circuit Diagrams - Make

                           

                          Luis

                          4 of 4 people found this helpful
                          • Re: Schematic
                            DAB

                            Hi Roger,

                             

                            I am slightly younger than yourself.

                            A good way to approach complex schematics is to create a block diagram view and then look at each section as it relates to the next block. This approach gives you a roadmap to follow as you work through the details of each block.

                             

                            DAB

                            2 of 2 people found this helpful
                            • Re: Schematic
                              makerkaren

                              Not sure if this will help. This is the circuit diagram from the TLC episode that just came out where I made a mask with a spinning pinwheel on it. It's a small motor controller that uses a pressure sensitive variable resistor as a throttle.

                              I highlighted the "power rail" in red.  All these will connect directly to + power. These all need to be connected somehow, the order and manner don't particularly matter. That includes R1 the 10k resistor, Pins 4 and 8 of the 555 timer, the diode D3, and the + terminal of the motor.

                               

                              In yellow I highlighted the "ground plane". All of these connections will go to - power. So one lead of each capacitor C1 & C2 (doesn't matter which lead because it's non-polar), Pin 1 of the 555 timer, and the emitter of the transistor all need to be connected to the ground plane.

                              All other connections go to other components or pins on the 555 timer.

                              Are you familiar with the symbols in this diagram and what components they correspond to?

                              For each component, do you understand which pin or lead on the component corresponds to the line of that symbol on the diagram?

                              5 of 5 people found this helpful
                              • Re: Schematic
                                idontunderstand

                                Karen

                                I watched the video with the rotating fan and was intrigued the way you made the connections under the board and for the first time began to get an idea. However the  connection part was sped up so still a little confusing. The schematic you have colour coded is a great help and almost what I need. However I do understand from your drawing the run of the positive and ground runs but what is, and always has been is all the other lines within the schematic that you have not coloured. Which is positive and which goes to ground. I know you will think this is a ridiculous question but I don’t follow the positive and ground runs inside the schematic.

                                Im not conversant with the 555 timer so don’t know what each pin does.

                                From the base of M1 the - sign is connected to the diode D3 which in turn connects to the positive plane, It appears to me, the novice, that negative is connecting directly to positive the diode D3.

                                From R1 to VR1 and to R2 appear to come from the positive plane and stops at D1, but then from VR1 it looks like power goes through D2 and also picked up below D1. I am so confused which is positive and negative. I know you will be thinking I am overthinking it but if you could draw on the flow direction and colour the lines within the schematic to show which is which. Is it that I’m not understanding the way the components operate that is confusing me?  I think i need to be next to someone while the circuit is built from a schematic to help me understand how it is put together.

                                 

                                love your videos.

                                 

                                thanks

                                 

                                Roger

                                3 of 3 people found this helpful
                                  • Re: Schematic
                                    genebren

                                    Hi Roger,

                                     

                                    I really do understand your frustration, but schematics can represent circuits that are very dynamic. What might be positive at one instance may become negative in another.  Then, there are relative degrees of positive (represented by number of volts above ground).  A voltage divider may take a 5 volt supply and generate a mid-point that is less than 5 volts, but still more positive than ground (0 Volts).

                                     

                                    In your comment above, you zeroed in on one of the more obscure aspects of the circuit, diode D3.  99% of the time the diode does absolutely nothing, it exists to route current back into the power rail when the motor is switch off (de-energizing Q1).  The motor has a magnetic field around it when the motor is driven (Q1 on), when switched off, the magnetic field collapses and generates a large voltage spike that could damage components in the circuit.  Diode D3, routes this current into the power rail.  Why not to ground?  If the diode directed current to ground, it would also short current to ground when the motor was on (not a good thing).  This concept is a little more advanced that beginner electronics, but it is an important lesson.

                                     

                                    When I was first learning electronics, I was fascinated by schematics.  I could not understand them in their entirety, but with time and education they became clearer and clearer.  Be patient, time and studying will allow you to understand schematics more fully.

                                     

                                    Gene

                                    4 of 4 people found this helpful