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46  Using Arduino / General Electronics / Re: How to use POTs on Arduino without over heating? on: July 12, 2014, 11:52:25 pm
You're doing it wrong... how do you have the 3 pins wired?
47  Using Arduino / LEDs and Multiplexing / Re: LED and resistor question on: July 12, 2014, 11:32:16 pm
The other way would be buy 2 more resistors calculated properly.

48  Using Arduino / LEDs and Multiplexing / Re: LED and resistor question on: July 12, 2014, 11:27:55 pm
Quote
how can you claim a diode does not effect the current?!
I did not say that I said it does not CONTROL the current.

Quote
What exactly do you think the 'current limiting' resistor is there for
You can not use the current limiting resistor method of controlling a high current LED effectively, it is not stable enough.

You have been told this many times and you still either do not understand or delight in getting beginners to destroy their components.


It DOES control the current, since there's a stable voltage.

And the reason he is having issues is because the resistor's value is not high enough, the current drop from a diode brings the current down to safe levels for both the resistor and led..


Now please explain to the world how my circuit will destroy the LEDs... you can't.



49  Using Arduino / LEDs and Multiplexing / Re: LED and resistor question on: July 12, 2014, 11:07:14 pm
Quote
1 diode should be enough to solve your issue.
No, that just reduces the voltage it does nothing about controlling the current. You have been told this many times before but still insist on giving this incorrect advice to beginners.

Here is an other simple constant current supply.
http://www.instructables.com/id/Power-LED-s---simplest-light-with-constant-current/


Ughh....

  how can you claim a diode does not effect the current?!

Secondly

What exactly do you think the 'current limiting' resistor is there for...


Maybe.... it's time to retire old man
50  Using Arduino / LEDs and Multiplexing / Re: LED and resistor question on: July 12, 2014, 10:52:42 pm
1 diode should be enough to solve your issue.

Image 1 is your setup, the 2nd is simply a diode in series.


The current will drop to safe levels for your led's...
51  Using Arduino / General Electronics / Re: Arduino Nano not Triggering a Relay on: July 12, 2014, 10:38:40 pm
Ah this uses the opto method!

Bring to gnd to turn it on.....
 5v to turn it off.
52  Community / Bar Sport / Re: The Cracked Pot on: July 12, 2014, 10:32:59 pm
At least the cracked pot offers variable resistance...
53  Using Arduino / LEDs and Multiplexing / Re: LED and resistor question on: July 12, 2014, 10:26:12 pm
So how would I drive it with a constant 3.4v when my supply is 5v. 

Tricky....

Basically there's too much current flowing int the LED's, ideally lowering the voltage will solve your problems...


Easiest way would be to place two diodes in series with the led, knock it down a volt, that (without pulling out the calculator) should keep the resistors cool enough..

Measure your voltage out...
Measure the voltage drop across the LED
Measure how many ohms from the resistor...

Then get back.
54  Using Arduino / Installation & Troubleshooting / Re: Is AnalogRead reference voltage actually 4.9V? on: July 12, 2014, 09:56:37 pm
Yup specifiy the voltage you read in code 4.9/1024.

I had a similar issue, in the end I supplied 5v directly into 5v in, to get that magical 5v ref value.

55  Using Arduino / General Electronics / Re: Arduino Nano not Triggering a Relay on: July 12, 2014, 09:50:16 pm
Which relay board?

Something's not right...
56  Using Arduino / General Electronics / Re: Reduced phone ringing voltage on: July 12, 2014, 09:20:51 pm
Hoe about a  current transformer?   When voltage is detected on the line , arduino fires off...

But, since that was your  job ..


57  Using Arduino / General Electronics / Re: Easiest way to step-up 3.7 Volts to 9 Volts on: July 12, 2014, 12:43:45 pm
No, the ldo regulator will supply around 3.8 to 4v!

Bypass the barrel, 5v straight into the board...

58  Using Arduino / General Electronics / Re: Reduced phone ringing voltage on: July 12, 2014, 12:41:34 pm
Due to the laws involved, esp if you mess up...

An alternative would be to slap on a piezo near to the phone, amplify the signal use software to determine if it's the phone or microwave going ding, it may not be as easy, but you aint risking a law suit either..
59  Using Arduino / General Electronics / Re: [partially solved] 12V relay not cooperating (mod.3393 to be used with Arduino) on: July 12, 2014, 12:31:16 pm
Look...


To energize the relay, 12v is required, normally 5v relays are used with Arduino to keep arduino from seeing more than 5v.  Thisis a 12v relay, this transistor is a pnp, unlike npn where you provide > 0.7 to turn it on, pnp requires gnd, to switch it off you supply the voltage on the emitter, 12v, we can't..

But wait...

When 12v is placed on the emitter, 12v - 0.7v we end 11.3v ish volts on the base, this keeps the transistor on and the collector drivez the relay..

So how do you bring the base to ground?  If there's 11v trying to flow into the arduino? That's why I suggested a zener and shunt the excess voltage/current keeping it below 5v ... my emulator suggests it works.
60  Using Arduino / General Electronics / Re: Voltage isolation on: July 11, 2014, 08:45:16 pm
For the ac you current transformer, as for DC, a voltage divider.

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