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Posted by on August 17, 2009, 8:02 pm
On Mon, 17 Aug 2009, l o wrote:
> Just be sure that you have a handle on the basics of electricity. You
> may already have the issues of voltage, current, wattage, and the
> basic components of resister, capacitor, inductor, rectifier.
>
> I would also add the transistor and LED as semiconductors that you
> need to get a good understanding of. Otherwise you may see a lot of
> "magic smoke" before you really understand what is going.
>
> Joe Dunfee
Thanks, Joe.
From my perspective, Ohm's law and such are pretty straightforward. Putting
them to practice however, will very likely cost me a few components, but I'm
trying to learn from others (and learning circuit diagrams seems the best
approach for that). I'm reading Circuit Cellar, Nuts and Volts, Servo and Make
magazine ... and while not *ALL* of it is clear, I'm beginning to see some
headway.
Getting the idea of using resitors to limit current, diode's to protect
circuitry and such is something I'm just now trying to get my head around.
Pull-up/Pull-down, current limiters, amplifiers, transistors, bias resistors
... man, there is a lot to learn!!
As indicated, my goal is to create a *SIMPLE* (small/light) circuit to
control BLDC's using a sensorless design ... ultimately to be able to tie
together a PWM power control via MOSFET's to the BLDC ... but there exists
a real mystery (in my mind anyways), at how to feed back the Back EMF from
the dormant phases of the motor to the processor ... I'm thinking via an
ADC, but I have to get the voltage/current scaled properly, and then
apparently find the crossover point (0V -- but relative to what??) ... as
in many things in life, timing is critical ... 8-)
Initially, I had thought that a couple of transistors might be used, but
apparently startup is critical, owing to the current draw, and will have to be
ramped up ...
I know that this project is perhaps over-reaching my abilities currently, but
if I get to the point where it all makes sense, then I will have accomplished a
fair bit ...
The funny thing is, programming the AVR's in C turns out to be the easiest part
of the whole thing (and an absolute BLAST) ... but I suppose that's because I'm
coming at this thing backwards ...
Cheers,
Rob.
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Posted by l o on August 21, 2009, 4:44 pm
I just realized that I did not make clear that the transistor, diode,
and LED are a different sort of critter. Semicondutors don't behave
the same as resistance loads. Also, it is starting to sound like you
really are engineering a circuit, not just making minor adaptions to
an existing design.
For that, nothing beats getting a text book and going through all of
it so you can know you aren't missing and understanding of important
stuff. It is the stuff you don't know about that makes the "magic
smoke".
Joe Dunfee
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Posted by on August 24, 2009, 3:10 pm
On Fri, 21 Aug 2009, l o wrote:
> Date: Fri, 21 Aug 2009 13:44:44 -0700 (PDT)
> Newsgroups: comp.robotics.misc
> Subject: Re: Smiley Micros and NerdKits ... (fwd)
>
> I just realized that I did not make clear that the transistor, diode,
> and LED are a different sort of critter. Semicondutors don't behave
> the same as resistance loads. Also, it is starting to sound like you
> really are engineering a circuit, not just making minor adaptions to
> an existing design.
Perfectly clear, and darned good advice. I'm looking at an electronics
book on analogue stuff, and will work through it. Thanks, Joe. As
indicated, the processor/semi programming is the easy part. The tricky
part is safely hooking it up to real devices ... and that's where I'm
struggling.
Cheers,
Rob.
> For that, nothing beats getting a text book and going through all of
> it so you can know you aren't missing and understanding of important
> stuff. It is the stuff you don't know about that makes the "magic
> smoke".
> Joe Dunfee
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Posted by BobH on August 24, 2009, 6:04 pm
Spam@ControlQ.com wrote:
> Perfectly clear, and darned good advice. I'm looking at an electronics
> book on analogue stuff, and will work through it. Thanks, Joe. As
> indicated, the processor/semi programming is the easy part. The tricky
> part is safely hooking it up to real devices ... and that's where I'm
> struggling.
>
> Cheers,
> Rob.
Something that would save you a mess of reading and probably some smoke
would be to talk with someone who knows about this stuff as you go
through the first few projects. Very little beats walking through a
design with someone as a way to learn.
Good Luck,
BobH
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Posted by waynegramlich on August 24, 2009, 8:52 pm
BobH wrote:
> Spam@ControlQ.com wrote:
>> Perfectly clear, and darned good advice. I'm looking at an
>> electronics book on analogue stuff, and will work through it. Thanks,
>> Joe. As indicated, the processor/semi programming is the easy part.
>> The tricky part is safely hooking it up to real devices ... and that's
>> where I'm struggling.
>> Cheers,
>> Rob.
>
> Something that would save you a mess of reading and probably some smoke
> would be to talk with someone who knows about this stuff as you go
> through the first few projects. Very little beats walking through a
> design with someone as a way to learn.
If you live in an area with a robot club, I would recommend
that you join. Since you are trying to figure out some
electronics stuff, the local amateur radio club is another
reasonable substitute.
-Wayne
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> may already have the issues of voltage, current, wattage, and the
> basic components of resister, capacitor, inductor, rectifier.
>
> I would also add the transistor and LED as semiconductors that you
> need to get a good understanding of. Otherwise you may see a lot of
> "magic smoke" before you really understand what is going.
>
> Joe Dunfee