Two questions holding me back. -Questions about getting started with electronic projects

Discussion in 'General Electronics Chat' started by David Deven, Aug 1, 2018.

  1. David Deven

    Thread Starter New Member

    Nov 4, 2017
    Hello all. I am new to this forum.
    I did read the rules first before posting.

    I have been interested in this field for quite some time but lack experience & $ to really do anything major.
    For me I always have trouble coming up with a decent name for the topic probably because of my Disabilities.

    I understand some of the basic functions of the components like Resistors,Capacitors and such.

    But please don't flame at me or anything even if I ask these questions in a weird way I learn in a unique way from everyone else.

    Right now I am having a few things holding me back from a small or at least I think is small project:

    1.How do I know what components will work with each other with problems.

    2.If I choose to modify a circuit that has already been made . How do I understand and know what changes of mine will work.
  2. David Deven

    Thread Starter New Member

    Nov 4, 2017
    I meant without sorry the time limit expired for editing my post.
  3. crutschow


    Mar 14, 2008
    Greetings and welcome to the forum. :D
    There's no simple rule to tell you that.
    It requires a good understanding of what the components do in a particular circuit.
    Again that requires knowledge of how the circuit works and how any proposed change with affect its operation.

    For starters, I suggest you read some electronic tutorials, such as at the top of this page under Textbooks.
    If you have any questions about that material, get back with us.

    Also a good way to experiment with circuits, and become familiar with their operation is with an analog circuit Spice simulator, such as the free LTspice download from Analog Devices (Linear Technology).
    It has a somewhat steep learning curve, but the tutorials and numerous demo circuits help with that, plus several on these forums can help you with any questions.
    NCSailor likes this.
  4. Reloadron

    Distinguished Member

    Jan 15, 2015
    I agree with crutschow with his response to your first question. Learning the different components and what they do will give you an idea of how well they play with each other.

    Working with a pre designed circuit is always a good start to modifying it to do what you may want it to do. There are likely a few million circuits out there on the Internet and likely half of them are poor designs and some are designs which simply do not and will not work. This is where I suggest circuits from credible sources and more important circuits with a good theory of operation description. With time you will understand how to use small circuits as building blocks to build larger more complex circuits. Start with small and simple circuits you can readily understand and work up.

    Just My Take....
    NCSailor likes this.
  5. ebp

    Well-Known Member

    Feb 8, 2018
    Welcome to AAC!

    Unfortunately, your questions are so general it is pretty much impossible to answer them. Electronics is a big big field, and it can be pretty daunting to just jump in and get started.

    It would be very rare to run into problems where one type of component is really incompatible with another. It is quite common to have situations where the best performance requires that components be considered carefully so you don't waste the ability of a really good component by using poorly-matched components with it. You do need to be sure the components are compatible with the job that needs to be done.

    Just as one example, there is often need to amplify a signal in a very precise way that is stable with time and temperature. You might use an operational amplifier ("op-amp"). Different op amps have different characteristics - some are good for very fast signals, some work well with low supply voltage, some have very good characteristics suited to the problem mentioned, some are inexpensive, some are very expensive. For the problem at hand, you would want to chose one whose characteristics are stable with time and temperature, is fast enough for the signal, works at the supply voltage you want to use, and doesn't cost more than the project budget allows. You have to learn the basics of how op amps work and what the specifications mean, and then spend time studying datasheets for ones you think you be suitable. The manufacturers' web sites have tools that help you pick appropriate parts. So do lots of companies that sell the parts. Once you find one that looks right, you need to add some resistors to the circuit to set the amplfication factor - "gain." Resistors also come in lots of different types with different characteristics - all will change in value with temperature, some quite a lot, some very little. Some aren't very accurate in value, some are extremely accurate. The cost of resistor to use with an op amp ranges from a small fraction of one cent to tens of dollars. If you want to make sure your amplifier works the way you want it to, you have to select the right type. For the circuit we are working on, we want resistors that have good accuracy and don't change much with temperature, but we also don't really want to spend twenty dollars per resistor if we don't have to. So we study the datasheets carefully to pick the types that look good and look at prices - both are pretty easy to do on the web. 40 years ago it took a whole lot more time to do the same thing. We might come up with some with characteristics that are good enough for out purpose that cost a dollar each - which most people now consider to be a pretty expensive resistor. But lots of time you don't need very high performance, so you can select common, inexpensive parts and do a perfectly good job. You can build an op amp circuit that is good for lots of things for 20 or 30 cents for the amplifier and the resistors.

    Making changes to an existing circuit usually requires that you understand the circuit quite well.
    If we again consider an amplifier, you might find a circuit on the web that looks close, but want to make one that has higher amplification. That can be done by just changing the values of the resistors, but doing that also changes the frequency range ("bandwidth") of the signal that can be amplified accurately. It can mean the circuit requires a bit more power. Once you gain some understanding of circuitry, something like that is often easy to do.
    Or maybe you want to change the speed at which a circuit flashes a light emitting diode. If you look at the circuit and find it uses a 555 timer, which is a very very popular part, you can get the datasheet and applications information for the timer on the web and they will explain how to configure the circuit according to the timing you want.

    Many people now use "simulation" software to evaluate circuits. Simulation would let you take an existing circuit and say "what if I change this resistor" and have the computer analyze just what would happen. You can do lots experiments that help you understand how circuits work without actually have to build anything. This is very powerful and useful, but it does take some time to learn how to use it. There are some very nice free simulation software packages available. Lots of people at AAC use LTSpice from Analog Devices. Lots of those people are also really generous with their time and great knowledge and will help beginners.

    If you have some circuits in mind you want to experiment with, there are many people at AAC who will try hard to help you. You need to be able to describe what you want to do and/or post circuit diagrams (schematics).

    I suggest you spend some time looking at things in the forum. In the "General Electronics Chat" category, lots of people look for help with all sorts of different things. This will give you some idea of how things work at AAC and what you need to do so people can understand what you are trying to do.

    I haven't been on AAC for very long compared with lots of people. It is one of the best internet forums I have ever seen, with many really good people who are kind, patient and extremely knowledgeable. Lots have been in electronics professionally for many years and have university degrees in electrical engineering (I don't) and some have been professional educators in electronics. You have to remember that everyone who helps on AAC does it for free and when they can spare the time, so you can't get pushy and demand people pay attention to your problem right away. There are people from all over the world, and someone who will help you might not even see your question until hours after you ask it. If you post requests for help be prepared for people to ask you a bunch of questions before they can give help. Once you've been through the process a few times you'll get better at being sure you give enough information so things don't go back on forth for several days before anyone can really begin to help you.

    Anyway, pick something you would like to start with and see how things go!
  6. dl324

    AAC Fanatic!

    Mar 30, 2015
    If you take the time to study the original circuit and understand why each component or component value was used, you should be in a position to make changes and be able to tell if they'll work without having to build or simulate.

    Making changes without understanding what the effect will be is just guessing. Sometimes you'll guess right, and sometimes you'll guess wrong. With the operative word being guess.
  7. DickCappels


    Aug 21, 2008
    It should be noted that trial and error is a good way to confirm your understanding of things of which you are uncertain. The more projects you complete (or even abandon in some cases) the more you learn.

    For now at least, limit trial and error to low power low voltage circuits. The higher the voltage, current, or power, the greater the potential cost of failure.
  8. Tonyr1084

    Distinguished Member

    Sep 24, 2015
    Three things, first Welcome to AAC. Second, there are no dumb questions. Maybe answers, but honestly, if you don't know something - by all means - ask. What's the worst you can hear? That we don't know the answer. Usually in that case we remain silent. The third thing is this, by way of example: I have a friend who doesn't know how to move a mountain. He can't figure out how to pick the whole thing up all at once and move it. Truth is - you don't move a mountain that way, you move it one stone at a time. One load at a time. Eventually you get the job done.

    That being said, and as others have suggested, start playing around with low voltage stuff. 5 to 12 volts is a good place to start. Grab an old cell phone charger and clip the end off of it and learn what those wires do. Experiment with something easy. Something you saw on the internet and would like to try it out. Reading about and understanding electronics comes one stone at a time. At first you'll build a small pile. But in time you'll be building castle walls.

    There are no dumb questions. Only dumb thing is to not ask when you don't know. None of us judge (I hope that statement is true). We all began at one point, and those here who have gained quite a pile of stones will be happy to help you understand those mysterious things that happen when you touch the ends of a double A battery to the wires of a transformer. You'll discover the joys of getting a shock. A small and harmless shock - unless you have a pace maker, in that case don't try that. But you'll want to know why you experienced what you did. We will explain it as best as we can.

    ME? I'm like you. I've spent a long time scratching the surface of electronics and never really went anywhere with it. I can help out with little things and I can certainly raise questions. Others here like Dick Cappels have a wealth of experience and knowledge that over the past few years I've watched them help others solve problems. They've helped me as well. So this is a good place to ask all your questions. People here will help.

    Again, welcome.
    shortbus likes this.
  9. David Deven

    Thread Starter New Member

    Nov 4, 2017
    Thank you all very much for your input. If I have any questions I will post back here if that's alright ?.
  10. Tonyr1084

    Distinguished Member

    Sep 24, 2015
    Eh! I suppose it's alright. No, really, it's alright.