Yes it does! You are mixing up the input impedance of the A/D with the output impedance you need from your input source to drive it. While the input impedance of the A/D is very high, if you just connected it up to a signal with a high output impedance then the input sample and hold capacitor will take time to charge up once you switch channels. Therefore you will not be able to measure several channels in quick succession. However, the analogue input will still have a high impedance.
For effective coupling between circuits the output impedance of one should match the input impedance of the other.
In testing everything works 100% so I am not exactly sure why I need to add more components.
really was aiming for super simple lol
anything you disagree with, then take up a new hobby.
That reffers to power transfer which is not what we are talking about here.
QuoteIn testing everything works 100% so I am not exactly sure why I need to add more components.Because you are not testing it enough you are just going off functionality, this is not good enough when dealing with hardware. You have to make sure that you are not stressing the components and that it will continue to work and not fail prematurely.Read this:-http://www.thebox.myzen.co.uk/Tutorial/LEDs.htmlAnything you don't understand I will be happy to explain, anything you disagree with, then take up a new hobby.Quotereally was aiming for super simple lolSuper simple designs are good but they need to be right, repeatable and work under all reasonable circumstances.
Two things- What is meant by "mux'ing"?Yes the LEDS are blue- I am using this: https://www.sparkfun.com/products/9191-These are running at 3.3v- but am I understanding now that they could pull 3.5 somehow?
While several people have correctly said that you need resistors with LEDs nobody seems to have actually explained why.
It wouldn't be the first time I've been confused. So clear things up and tell me what are we talking about here?
I don't however feel that this needs to be repeatable
These are running at 3.3v- but am I understanding now that they could pull 3.5 somehow?
So you project needs to be even more complex than just adding a resistor, you need a boost constant current LED driver.
Quote from: Grumpy_Mike on May 02, 2013, 02:50 pmSo you project needs to be even more complex than just adding a resistor, you need a boost constant current LED driver.Absurd.
Grumpy_Mike,pcguru has an Uno (it's there in his big darned PNG), there's 5V available on it - which I noted in my Reply_#37: "Anyway, you should have the CA wired to +5."He was putting the 7-segment's CA to 3V in the belief, howbeit mistaken, that that would obviate any need for resistors.
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