Connecting the dots - Page 1
Forum section: electronics / beginners

author: easilyconfused
author_rank: Regular Contributor
timestamp: July 31, 2010, 06:42:58 pm
content: Mostof the time I think I'm wasting my time in the pursuit of understanding electronics. It's probably just too far over my head. And-- I'll probably give it up after a while. But every now and then I run across something that makes me think I just might pull it off. I ran across this little video. I don't understand all of it. But anytime a video or text tutorial limits itself to a very simple thing I tend to understand better. I thought I'd share it with you.Two things account for my failure toacquire: the abstract nature of the subject (invisible power), and a short attention span. Making the abstract easy to understand is hard. Keeping the object lesson short should be fairly easy. This guy did both.(I initially posted the wrong site- sorry)

author: saturation
author_rank: Super Contributor
timestamp: July 31, 2010, 07:13:42 pm
content: Consider making the theoretical real by playing with the concepts with any one of those 300-1 learning kits. You can go at your own pace, have all the parts needed for the project, don't have to solder or build PCB boards, and get to the heart of the issue, the interaction of the components. There are many types, the snap kit looks better in that the parts assemble like a schematic:The traditional design is more compact but looks more abstract when assembled, as the spring joints get connected by a swirl of wires as designs get bigger.I think you can download the user manuals and decide which type is better, and what you can build with it.If you think you might give it up after a while, why spend too much money on good equipment that will not get good use?If you give up on the kit, its not more than dinner and a movie for two.Quote from: easilyconfused on July 31, 2010, 06:42:58 pm

author: Simon
author_rank: Unknown
timestamp: July 31, 2010, 08:14:17 pm
content: interesting concept, far beyond my mathematical reach

author: djsb
author_rank: Super Contributor
timestamp: August 01, 2010, 12:36:01 pm
content: I did the final year project of my HND on a motor speed controller. I used PWM to control the motor and an optical sensor to detect the rotational speed. All of the things he mentioned in the video are real issues when you deal with motor drive electronics. It takes time to understand the concepts behind back emf (electromotive force) but this is covered when studying inductance, faradays laws etc. The theory only makes sense when you get your hands on real parts and use them.I found the video really good at explaining things. Had at look at some of the others as well and they're equally as good.David.P.S If you want some theory look herehttp://en.wikipedia.org/wiki/Faraday%27s_law_of_inductionMore on motorshttp://en.wikipedia.org/wiki/Electrical_motor

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 02, 2010, 04:09:24 am
content: may i draw a question? whats the benefit of mosfet compared to normal bjt transistor?

author: allanw
author_rank: Frequent Contributor
timestamp: August 02, 2010, 01:01:51 pm
content: It doesn't need a constant current into the base to operate. So there's no need to calculate a base resistor value. Also no ~0.3V saturation voltage drop, only a drop from the MOSFET's R_DS value.

author: jahonen
author_rank: Super Contributor
timestamp: August 05, 2010, 06:01:44 am
content: MOSFET is faster (particularly on turn-off) and drain current is really limited by thermal stuff (forget about Id max spec, static maximum current is determined by Rds(on) and thermal resistances, along with ambient and maximum junction temperatures), no secondary breakdown (formation of hot-spots in silicon), so they are very robust against momentary current spikes. It is amazing how much abuse a MOSFET can take for momentary currents, assuming no overvoltages present, of course.Regards,Janne

author: Unknown
author_rank: Unknown
timestamp: August 05, 2010, 03:07:16 pm
content: A MOSFET is faster as long as you have a beefy MOSFET driver (dis)charging the gate capacitor, not if you try to drive a power MOSFET from a wimpy logic pin.

author: Time
author_rank: Frequent Contributor
timestamp: August 05, 2010, 03:45:26 pm
content: Quote from: alm on August 05, 2010, 03:07:16 pmGood point. I am working on something based around a 500V RF power MOSFET and driver. The driver itself can produce 20 amps. The layout of the devices turned out to be important too.

author: shodan
author_rank: Contributor
timestamp: August 11, 2010, 08:28:55 am
content: thanks guys, this is why I come to this site !!undiluted useful design knowledge !

author: bearman
author_rank: Regular Contributor
timestamp: August 18, 2010, 07:27:18 am
content: Definitely get one of those 200 in 1 project kits. That is how I graduated from electrical stuff (motors, light bulbs, relays, electro magnets, switches) to true electronics (diodes, transistors, resistors, capacitors, inductors).Another advantage is you have all the parts you need to build stuff right in the kit. If you try to learn by building misc. circuits off the web you will be buying all kinds of stuff you may never use again or you can't get things to work because you can't locate the exact part required. Get the kit to eliminate all those distractions. Its well worth it.Those kits give you schematics, circuit functional description and theory of how is all works step by step. That will be very helpful to you based on your questions.The step by step walk through helps you learn what each component does. I was building stuff in no time.As your knowledge grows you will learn basic electrical theory and apply numbers to the circuits and learn how to design these on paper before touching a single wire and making it work based on your engineering skills.Good luck. I got my 100 in 1 project kit from Radio Shack in 1967 and it launched my electronics hobby that is still going today 43 years later. OH! I still have my Radio Shack 100 in 1 kit by the way.Bearman

author: scrat
author_rank: Frequent Contributor
timestamp: August 18, 2010, 09:10:09 am
content: Quote from: shafri on August 02, 2010, 04:09:24 amPower MOSFETs can also be easily parallelized, since there is negative thermal feedback.For high voltage I see a positive trend for IGBTs, which are something in the middle between BJTs and MOSFETs.

author: orbiter
author_rank: Frequent Contributor
timestamp: August 19, 2010, 03:24:17 pm
content: @easilyconfused..Your not on your own mate.. I've tried getting to grips with electronics a few times too in the past and normally given up after a few weeks. However I'm 42 now and am not letting it go this time. I'm resigned to the fact that I am going to learn at a very slow rate though, and just hope that one day in future, I'll be able to look back at things I struggled with and be able to carry them out with reasonable ease. It's mostly the maths for me though, I was never very good at it at school and still hate it today, although I'm trying my best to understand some of the various calculations and what they relate to and why.The internet makes things a lot better though, and places like this are a god send, especially with the many knowlegable guys we have here who are always kindly happy to help.RegardsJohn