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1  Using Arduino / General Electronics / Re: 24VAC to 24VAC transformer? on: Today at 07:50:39 am
2  Using Arduino / General Electronics / Re: Im programmer who interested in Arduino help on: Today at 07:28:43 am
I don't nothing about electronics . i know only c/c++ programming .
to lean arduino , should i learn electronics or i don't need it at all .
Thank you

I'd say.... in between  2
how much you need to learn depends on what you want to do.
the very basics should be enough to get started
IMO, Ohm's law is mandatory and then, there are a lot of books about arduino (some from this forum members ) , and I think most of them teach what you need to know (transistors and mosfets as switches, LEDs, relays etc.... )
3  Using Arduino / General Electronics / Re: 24VAC to 24VAC transformer? on: Today at 07:18:53 am
Isolation transformer for use with 24Vac industrial control gear.  24V supplies are
used in industrial control a lot.

Righto.... still wondering why the word isolation doesn't feature on their page, but thanks guys.
it does :


4  Using Arduino / General Electronics / Re: What is this component? Transformer? on: September 07, 2014, 05:06:34 pm
OK, and thanks for the precisions  smiley

5  Using Arduino / General Electronics / Re: What is this component? Transformer? on: September 07, 2014, 04:13:32 pm
adjustable inductor, I think . There were a lot of them in old radios
6  Using Arduino / General Electronics / Re: Wiring Capacitors in Series on: September 07, 2014, 06:40:59 am
Then he would have needed to put them in parallel, and that's not what he's asking about.

Also he is convinced that his photo of the breadboard shows a clear picture.
He seems to have used purple (or is it brown ?) for GND and yellow for all other functions (with exception to a wire at the IR receiver), and has crossed wires without need.
If that is true, the right capacitor has a purple wire to its unmarked side, which is positive, and not where GND goes.
Its marked side is connected to the unmarked side of the other capacitor, so that one must be reverse connected too.

yep, thus my use of the  smiley-mr-green  smiley  , and we are still waiting for an answer about these 2 caps

not sure about the colours, they seemed to be used randomly
7  Using Arduino / General Electronics / Re: Wiring Capacitors in Series on: September 06, 2014, 03:08:50 pm
Now to those capacitors.  The one visible is 680 µF at 10V.  Well, since your two CR2032 cells in series sum to 6.6V, that voltage rating would be perfectly sufficient alone as a reservoir capacitor connected across the batteries as you have the series pair - if only you had it connected the correct way aroundYour photograph however shows yellow wires connecting together the battery positive, the positive wire of the piezo sounder, and the negative (the one with the white bar and "-" signs) connection of one capacitor, whose positive is connected to the negative of the other.  You thus have both capacitors connected in reverse, which will indeed cause progressive degradation of the capacitors but at these voltage levels, explosive failure is quite unlikely.

Finally, your first attempt at a schematic circuit sadly bears no resemblance to the actual circuit though I am impressed at your correct use of "mu" (µ) as a shorthand for "micro".

hum... I disagree.
here is what I can see :

V+ --> + 680 µF - --> + xx µF - --> +buzzer - -->  and so on....
which corresponds to the schematic smiley-wink
but I don't quite understand the need of 2 caps , maybe he wants 1000 µF and he doesn't have one  smiley-mr-green
8  Using Arduino / General Electronics / Re: MC34063 buck with large variable input? help on: August 13, 2014, 12:00:46 pm
Would ACT4088 chip be a good option?
 I really like the price and minimal components on this chip.

I know this chip has a wide input range based on the datasheet, but I still can't determine if this means you choose the external components based on a fixed input within the allowed range, or can the input be variable to the completed circuit for flexibility to the end user?

I need an input range of about 7v-24v DC, to provide 5v output, ranging from 100ma to 500ma, but 1000ma would be nice to have if possible.

any suggestions would be great.

as far as I can see, the output voltage only depends on Rfb1 and Rfb2 - 

but, the efficiency decreases as the input voltage increases, and is not good at low load current values ,  you should have a look to the typical performances curves, to see if it suits your needs .
9  Using Arduino / General Electronics / Re: what's this phenomenon called? on: August 13, 2014, 05:28:42 am
symmetrical power supply
Even if the voltages are not the same? Like +12V & -9V.

no, just for same voltages
10  Using Arduino / General Electronics / Re: what's this phenomenon called? on: August 12, 2014, 06:35:54 pm
Placing batteries in series no problem.. add the voltages.

But when you use ground between the 2 voltages we get a voltage shift, anyone know the name of this?

symmetrical power supply  (that's how it is called in french)

lool, Awol  smiley-lol
11  Using Arduino / General Electronics / Re: use 50+ LEDs and arduino on: August 10, 2014, 10:40:08 am

if i use this kind of schematic and control 10 transistors using arduino to power up 50 leds, Does this would be normal ? I'm also interested in whether 12 volt 2A power supply is enough for arduino plus LEDs?

it won't work :

1- the Leds you'll buy are pre-wired with a series resistor, for a 12V power supply - Thus you can't put 10 of them in series with a 12V power supply

2- with a npn transistor, you must put the load (here, the led and included resistor) between +Vcc and Collector, and emitter to 0v . Don't forget to put a resistor between the arduino output and the base !!
Search this forum (or google) with the words "arduino, transistor, switch" and you'll find a lot of examples .
3 - you should check the included resistor value, it will tell you how much current each led needs .

12  Using Arduino / General Electronics / Re: The terms "common emitter" and "emitter follower" on: August 02, 2014, 01:29:08 am

It's not intuitively clear to me where the terms come from... can someone elucidate please? What do they mean?

the common collector configuration is also called "emitter follower" , just because the output 'follows' the input (unity voltage gain)
13  Using Arduino / General Electronics / Re: Voltage divider on: July 17, 2014, 10:01:19 am
I strongly suggest that you don't try and divide 9V down to exactly 5V. Your battery probably charges to something higher than 9V, and if the battery dies, the charger will almost certainly drive it to a few volts over 9V.

But if you've exactly divided 9V down to 5V, that puts more than 5V, ie, more than Vcc on an analog pin. That is not a good thing to do. It will have the high resistance in series with it, but it is still not a wise idea.


what about a 5V zener diode  // with R2 ?  it will protect the input
14  Using Arduino / General Electronics / Re: Power-up the arduino uno with external 5v dc through the 5v pin. on: July 06, 2014, 04:05:09 pm
Arduino uno produce 1 ampere current from the transistors.if we want more than that,
The best way to supllier the 5vdc from external sources.

15  Using Arduino / General Electronics / Re: Question about the transistor TIP122 on: June 29, 2014, 02:17:31 am
Hi  Jeff27,

I (or others here) could answer your questions one by one ( Ic = collector current.... Hfe = current gain etc... ) , but I think you'd better have a look here :

and then here (more about darlington transistors)

you'll get answers to all your questions, and more smiley
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