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661  Using Arduino / General Electronics / Re: new components on: February 03, 2014, 08:57:41 pm
This is why nasa does not have a public forum lol...

What concerns me is... where did he get all the terminology from (zener, flyback etc) to begin with and why is he not using a search engine?

Diodes like transistors behave differently based on how you wire it up, get googling.
662  Using Arduino / General Electronics / Re: What is this? on: February 03, 2014, 08:53:26 pm
You know what, you could use the ic chips to pin back the curtains or other fabric  (using 2 ics to clamp together)
663  Using Arduino / General Electronics / Re: SSR with Android - Do i need a resistor here? on: February 03, 2014, 08:50:21 pm
No harm will result from adding a resistor when you're unsure. 
And better that than the way so many around here go about things.


So there is no instance where adding a resistor can cause harm?

I bet it could, thinking along the lines of sensors used for safety, eg if you used one on a distance or heat sensor you could stop it working or go weird and a robot connected or car, could then screw up and kill you by not seeing you...

664  Using Arduino / General Electronics / Re: why do we need a resistor connected to the base of the transistor? on: February 03, 2014, 08:45:48 pm

I don't like op-amps... sure they are useful but I'll use transistors when possible, I use them mainly for comparitor circuits, checking voltage level (with a zener)

If you want current regulation a zener and a resistor/transistor would do nicely avoiding an op-amp

Did you honestly completely miss the point of my post? 

I have a habit of reading just the technical side and ignoring opinion.    And well to answer your question, helping people here esp when the person is new here, I think it is better to tell them what they need rather than spell it out for a thankless task, otherwise they wont learn and you'd have done the work for them!

I started out with your exact same opinion, but in the long term it's not helping them improve their skills at all, telling them to google bjt/fet/whatever at least gives them a starting point.
665  Using Arduino / General Electronics / Re: What is this? on: February 02, 2014, 06:16:25 pm
They are IC chips designed to petform a single task, what that task is depends on the IC.

It could be anything hence the google search.
666  Community / Bar Sport / A broken Arduino... on: February 02, 2014, 06:10:51 pm
What should a dead arduino board be called?

Deaduino? Or are you now a Boreduino? lol  yeah I'm majorly sleep deprived.
667  Using Arduino / General Electronics / Re: why do we need a resistor connected to the base of the transistor? on: February 02, 2014, 06:06:19 pm
And here was me thinking all these years that transistors (BJT) were current amplifying devices.  
Gain or Beta is I Collector / I Base
Doesn't that mean that a transistor needs current to work and that can only come from a current source.

It's funny how a lot of people here try to one-up each other with semantics, technicalities and pointless details.

Yes of course the gain of a BJT is Ic/Ib and it's called "current gain". An analog voltage signal applied to the base of a BJT through a resistor creates a varying base CURRENT which is amplified by a factor of BETA and appears as varying collector current with a magnitude of Ib times BETA.

However, the term "current source" usually refers to a circuit that supplies a constant (or adjustable) current. For example, a current source set to 20 milliamps and with a compliance voltage of at least 2 to 3 volts would nicely drive an LED.

However, you don't build a complete "current source" circuit to drive an LED... you just use a resistor and call it "good enough".

Would you use a circuit like this:



...just to drive an LED?

IMHO, replies to OP's should be tailored to the question and to the perceived knowledge level of the poster. Rather than saying something like "you use a resistor to control the current" (which means NOTHING to a person who asks such a question), I think it's better to explain exactly what's going on, and if possible use a MECHANICAL example (which people can much more easily relate to) to describe what's going on.

I've been teaching for over 20 years and I have yet to encounter anyone (who is awake) that can't "get it" after I explain it.


I don't like op-amps... sure they are useful but I'll use transistors when possible, I use them mainly for comparitor circuits, checking voltage level (with a zener)

If you want current regulation a zener and a resistor/transistor would do nicely avoiding an op-amp
668  Using Arduino / General Electronics / Re: why do we need a resistor connected to the base of the transistor? on: February 02, 2014, 05:57:51 pm
why do we need a resistor connected to the base of the transistor?

Simple: To prevent more than 20mA coming out of the Arduino pin (which might damage it).

(Usually you limit the current to a lot less than 20mA but that's the reason).

.

That's not why a resistor is needed on the base pin of the transistor, the resistor is there to limit the current flowing into the transistor via the base... 
669  Using Arduino / General Electronics / Re: Powering more components on: February 02, 2014, 05:53:45 pm
The arduino has plenty enough voltage,  it lacks current.

670  Community / Bar Sport / Uplink/Downlink to Mars. on: February 02, 2014, 08:51:49 am
Everytime I see something from NASA or some doc i'm watching, they always (always) go on about the slow
data rate between the rover and earth and fair enough right, it takes a day to send a packet from here to there.

So while being bored I thought to myself, internet on mars, no.

but, I would be able to still recieve data, collect my emails live on mars in peace right! so it got me thinking
what is the fastest transfer rate? I originally thought a low bit stream maybe similar to 56k modem..

turns out that if done correctly, TV streaming, just high data rates are possible to mars! - take a look
at the attachment... 

which is annoying  considering i only get 4.9mbit while someone on mars could be streaming
TV up to 150Mbit...  i'm on this planet and the best connection i can get is 4.9mbit  smiley-confuse
671  Using Arduino / General Electronics / graphine and silicon radio broadcast! on: February 01, 2014, 07:02:05 am
http://www.newscientist.com/article/dn24976-first-graphene-radio-broadcast-is-a-wireless-wonder.html


IBM managed to do broadcast "IBM"  it seems the first graphene devices may use silicon wafers!
672  Community / Bar Sport / Re: For the seasoned contributors on: January 31, 2014, 08:18:12 pm
I showed my 11 year a floppy disk, she said, yeah we have them at school....

I was in shock lol (at the school i send my daughter too!)
673  Community / Bar Sport / Re: Arduino compatible ZIF socket, WTF? on: January 31, 2014, 08:13:39 pm
mmmm, have I been missing out on all the action again ?

    girlfriend, wanted, must be Arduino plug and play compatible   smiley-kiss
____
Paul


does it matter if she's 8bit or 32bit ?
674  Community / Bar Sport / Re: Arduino compatible ZIF socket, WTF? on: January 31, 2014, 12:32:23 am
I'm waiting for an Arduino food products... some chips and sauce to go...
675  Community / Bar Sport / Re: electric generator idea plausible? on: January 31, 2014, 12:29:59 am
The idea is to generate as much power as possible from using your arm..

Faster the gyro, more power ..  ac not a problem with a diode rectifier..
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