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1  Using Arduino / General Electronics / Re: can someone please confirm if this mosfet will work? on: January 04, 2014, 08:56:41 am
Datasheet says that its fully open at max 4V, so the Arduino will open it properly.
I guess your next challange it to speed up PWM to at least 20kHz .. then some filtering.



NO NO NO!!

Firstly in English "open" for a switch means "off" or "no connection" as in "open circuit",
its not like a water tap at all.  I presume you mean "fully on at max 4V".

That MOSFET is not logic level and certainly is not switched on at 4V.

Perhaps you think threshold voltage is when the device is on?  Its not, its the point
at which the device switches OFF, or more precisely conducts only a few microamps.

The voltage at which the device is guaranteed to be fully _on_ is given in the Rds(on)
spec as the Vgs value - here its given as 10V for a Rds(on) of 32 milliohms max.

That means you need at least 10V between gate and source to guarantee the on resistance
is at or below 32 milliohms.

In general a logic level device will have Rds(on) quoted for Vgs = 4.5V.  It will also
likely have a threshold voltage of 0.5 to 1.0V.


Anyway, back to the original question.

Yes you can use that MOSFET but you will need a MOSFET driver chip to drive the
gate and a 10 to 12V supply to power the MOSFET driver.

With high voltage high power switching you cannot safely drive the gate directly from
an Arduino anyway as the drain-gate capacitance can back-drive the gate and burn
out the Arduino - you need a beefy driver chip to hold the gate voltage steady, something
like the MIC4422 will do nicely.

Again with that big load voltage you need to think about protection circuitry really -
a TVS diode to protect the 12V rail from over voltage, a 15V zener on gate-source
to protect gate oxide layer, a 10k resistor between Arduino and MOSFET driver to
protect Arduino.

But also we need to establish why you are trying to use low-side switching in the first place,
is seems unrelated to "regulating a power supply" - that would imply high side switching
if anything, which at 120V is rather more complex.

Wow, ok this is great information. I will try using this mosfet with the mosfet driver you suggested. Would you mind possibly keeping in contact with me if I have any questions when I receive the ordered pieces? This project is very important to me, however it would be nice to have some guidance and you seem to really know what your talking about.
2  Using Arduino / General Electronics / can someone please confirm if this mosfet will work? on: January 03, 2014, 06:54:58 pm
Hi there.
I have a 120v 10a DC power supply that I need to regulate with a mosfet.
I realize this is a bizarr request.

I have come across this mosfet: IPP320N20N3 G-ND
which seems to meet my needs.

Can someone please simply confirm if a pwm signal from the arduino to the gate of the mosfet modulate it properly?

I have tested the circuit with the irfp250 which has all the same specs except being able to use logic level. So I am regulating it with 0-12v instead of pwm from the arduino. It works perfectly in this way, now I just want to control it with the arduino instead.

thanks
3  Using Arduino / General Electronics / Re: Help with this triac circuit on: November 30, 2012, 05:03:50 pm
If your new to electronics I'd strongly suggest avoiding anything to do with mains voltage - lethal voltages are not the place to
start.


I'm sorry, what I meant to say is that I am new to arduinos and microchips etc.
I have built several tesla coils over 1kw and many other dangerous hv projects, so safety should not be a concern.
I just really need someone to help me out with the coding of this project and with the pin connections I did not understand. Or provide me with a link with the answers in them. I have not found the answers anywhere which is why I am needing help with them.

If this is the wrong place to be asking, where should I repost this question.

4  Using Arduino / General Electronics / Help with this triac circuit on: November 30, 2012, 01:09:45 am
I want to do this:

but with only 1 strand of led christmas lights.


I think I understand most of it. Basically you are detecting then the ac switches from pos. to neg. and telling the triac not to turn on until a few miliseconds after that, and the delay essentially controles how bright the light will be.

Here is what I dont understand:
-for the IL250 schematic, what is the top right pin hooked up to (pin B) ? it says DIP_6 IL250 or something.

- for the second schematic, what is pin 6 of the MOC3020 connected to? it looks like a plug for ac?

-for pin 1 of the MOC3020, what is that connected to? I'm not sure what Vcc means (I think it means +v?) and what is the value of the resistor with it? (Rin).

-How would the code be writen? Does the IL250 zero cross detection send a high or a low signal into the arduino? And how would you use that information to send to the triac?


As you can tell, I am pretty new to electronics and arduino's, but I absolutely need to get this project done.

I really appreciate the help!

Thanks,

James
5  Using Arduino / General Electronics / Re: dimmer circuit idea for ac? on: November 26, 2012, 06:33:14 pm

Quote

It could be made to work, it would act as an extremely power source of radio frequency interference and solving that would be more complicated than using a standard solution, a zero-crossing dimmer IC driving a triac.

is there an easy to follow instruction guide that you know of to do this? This would be what I want to do: (but only needing to control 1 light)
but some things in this video confuse me such as any of the coding, and pin connections
6  Using Arduino / LEDs and Multiplexing / Re: can leds meant for ac be run with dc? on: November 25, 2012, 11:57:11 am
So the more leds that I hook up, will that affect yhe current or voltage? I am hoping to make a box that I can just attach different amounts or types of led christmas lights too, so its not exactly an exact amount of lights or exact type that I will always be using. Kind of like a universal dc variable power supply to leds
There's no issue of "universality" here.
I think you have the wrong idea.

> > > Still, applying HVDC to the AC plug, as I believe you propose, would result only lighting, possibly, half the LEDs - if they're like dirtside's (and I don't insist that they are).  What to do depends on what you have.  There's no "universal" here, none.

Ok, just one last quick question if you don't mind.
Say I hooked up led Christmas lights to mains, but just wanted to dim them manually, would I use a variable resistor rheostat or a variac?

I really appreciate the help
7  Using Arduino / LEDs and Multiplexing / Re: can leds meant for ac be run with dc? on: November 25, 2012, 11:38:47 am
See my previous reply.
(There are no "ac leds".)
Read the link in the previous reply, too.

Oh ok! Sweet!
So the more leds that I hook up, will that affect yhe current or voltage? I am hoping to make a box that I can just attach different amounts or types of led christmas lights too, so its not exactly an exact amount of lights or exact type that I will always be using. Kind of like a universal dc variable power supply to leds
8  Using Arduino / LEDs and Multiplexing / Re: can leds meant for ac be run with dc? on: November 25, 2012, 11:25:15 am


Right...so how many DC volts does it need?

[/quote]

I have no idea. That's kinda what I'm asking. Is there a difference between an ac led or a dc led? Will ac led christmas lights even turn on with dc
9  Using Arduino / LEDs and Multiplexing / Re: can leds meant for ac be run with dc? on: November 25, 2012, 11:13:49 am

[/quote]

What voltage will it need?


[/quote]

It would originally take 120v ac...
10  Using Arduino / General Electronics / Re: dimmer circuit idea for ac? on: November 25, 2012, 10:48:18 am
How would all of that be less "rediculously complicated" than "using a triac and zero volt detection and stuff"?

http://arduino.cc/forum/index.php/topic,134127.0.html
http://arduino.cc/forum/index.php/topic,133921.0.html

Well I just think triacs and zero volt detection is pretty complicated for people like me who are new to electronics and coding.
My idea only uses 3 simple main parts that are easy to understand their function.
As for the coding, I don't understand at all the coding involved with zero volt detection and then how to send that into a triac etc.
Where as with my idea, the only coding involved is sending variable voltage to the pin of the mosfet
I.e. digitalWrite(pin, output value from 0-255);

Also,  I am using this to dim led christmas lights, so I don't know how well that will work with a triac.

Ill take a look at those links, but in the meantime, could someone shed some light on if my idea has any potential of working?
11  Using Arduino / LEDs and Multiplexing / Re: can leds meant for ac be run with dc? on: November 25, 2012, 10:20:47 am
I plan on running some led christmas lights on a mosfet controled by an arduino so that I can dim them. Will it work?

That depends totally on how the LEDs are wired. It's difficult to see that from here.



Well I would just be hooking it up to led christmas lights the same way you would ac. But just running them with dc instead
12  Using Arduino / General Electronics / dimmer circuit idea for ac? on: November 25, 2012, 09:34:55 am
I'm almost sure this won't work because someone would have done this before, so I guess I'm mostly asking WHY this wouldn't work..

I've been looking at ways to dim lights with an arduino. It is rediculously complicated (especially for someone like me who is new to electronics) using a triac and zero volt detection and stuff.

And I was also looking at using a mosfet to control them, until I learned that a mosfet will only work with AC.

So I was thinking, what if I had ac mains converted to  dc power (transformed, rectified, and smoothed) ran the dc through a mosfet controled by the arduino (so now I have the dc variable power) and then ran that through an inverter. So the inverter output will be variable because it is getting variable dc input from the mosfet.

What am I missing here? Is there any chance of something like this working?
13  Using Arduino / LEDs and Multiplexing / can leds meant for ac be run with dc? on: November 25, 2012, 09:19:12 am
I plan on running some led christmas lights on a mosfet controled by an arduino so that I can dim them. Will it work?
14  Using Arduino / Audio / how to only detect bass (audio detection) on: November 25, 2012, 01:01:05 am
Hey there,

I just completed this circuit http://www.picaxe.com/docs/picaxe_sound.pdf

It works fine, however I am using it to detect audio to make leds flash. I only want them to flash when there is a bass beat.
for example, a steady bass beat with someone singing over it would only flash with the bass beat and not with the singing.
Instead, this circuit picks up treble and bass, so whenever I play any song, the led flashes like a jumbled mess along with singing. It almost looks like it is flashing at random when music is playing.

any tips?
 I am new to electronics (this is actually my first arduino project) so bear with me.
15  Using Arduino / General Electronics / Re: HELP! problems with audio detection circuit on: November 24, 2012, 11:20:33 pm
i turned the diode around and it seems to work now. weird. i thought the black line was the cathode. doesnt it look right in the picture?
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