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16  Using Arduino / General Electronics / Re: How come my MOSFET was a "smoking", I thought it was rated high enough. on: September 24, 2012, 11:44:44 pm
http://www.jaycar.com.au/productView.asp?ID=ZT2225

there is a pdf data sheet there
17  Using Arduino / General Electronics / Re: How come my MOSFET was a "smoking", I thought it was rated high enough. on: September 24, 2012, 09:50:33 pm
how about a BUZ71
www.jaycar.com.au/images.../BUZ71.PDF

has a vgs of max 4v

should only need one as it can switch 50v  14A

ohh, and a heatsink
18  Using Arduino / Project Guidance / Re: DS18B20 Temp sensor not working with arduino? on: September 24, 2012, 07:35:29 pm
doh!  just testing you lot. lol.   will have another go when i get home from work
19  Using Arduino / General Electronics / Re: How come my MOSFET was a "smoking", I thought it was rated high enough. on: September 24, 2012, 06:03:37 pm
yeah righto , totally confused now, lol.

This is where I get my parts from as the hve a shop in town.  http://www.jaycar.com.au/index.asp

Can some one find me a suitable mosfet, the one you mentioned the IRL540 is not listed (I do not think) . 

20  Using Arduino / General Electronics / Re: How come my MOSFET was a "smoking", I thought it was rated high enough. on: September 24, 2012, 04:55:55 pm
ahh, so instead of being the 120deg as mentioned before with no heatsink, with the heatsink it would only be 38deg then?
21  Using Arduino / General Electronics / Re: How come my MOSFET was a "smoking", I thought it was rated high enough. on: September 24, 2012, 04:46:33 pm
The one that is smoking is a to220 size, but just no heatsink.

How did you work out that the bulb has a resistance of 3ohm when fully lit?

What is that 15x15x8mohm calculation called, so I can look it up and study it a bit.

I am aware you can also calculate how much temperaure a heatsink will suck off the mosfet. But what size do I get 1" x 1" size?
Ahh, just had a look at it in a catalog and it says a degreeCelcius/W
example there is one here that is for a to-220, that is 19degree celcius/W (watt I assume)

How does this work then?  It will suck away 19 degrees for every watt of power?
Then if I look at the much larger heatsinks they are rated at like 1.4degrees celcius/W, I know they will take the heat away better than the smaller ones but they have a lower temp/watt value???
22  Using Arduino / Project Guidance / Re: DS18B20 Temp sensor not working with arduino? on: September 24, 2012, 04:32:55 pm
Ok here are some pics.

23  Using Arduino / General Electronics / Re: How come my MOSFET was a "smoking", I thought it was rated high enough. on: September 24, 2012, 04:23:59 pm
Okay I have made up a diagram, and have noticed a wrong hook up.  You will see a red line where it is wrong.

Yes it is connected to a PWM output on the arduino.

I have a smaller mosfet to turn the bigger one one, like a darlington pair I guess.

See the schmatic.
24  Using Arduino / Project Guidance / DS18B20 Temp sensor not working with arduino? on: September 24, 2012, 09:02:06 am
My temp sensor is not working with arduino.  I have it hooked up right (I think). When hooked up the on board arduino led goes very dull, and then the USB connection drops out and the arduino is no longer connected to the PC.

When I pull out the ground or the 5V wire from arduino , the led lights back up and the board reconnects to the PC.

I am following these instructions: http://bildr.org/2011/07/ds18b20-arduino/

It is like it sucks too much power???

25  Using Arduino / General Electronics / Re: How come my MOSFET was a "smoking", I thought it was rated high enough. on: September 24, 2012, 08:11:49 am
Yes I do remember reading something about that.  It is getting about 12.56v to turn it on.  Which is what is switched on via the smaller mosfet behind it.

All I have to work with is that 12.5 volts.  Should I source a better suited mosfet?
26  Using Arduino / General Electronics / How come my MOSFET was a "smoking", I thought it was rated high enough. on: September 24, 2012, 07:41:03 am
I have used a small mosfet that will switch via the 5V signal from arduino into another larger mosfet that is hooked to a 12 50W halogen down light.

The bigger mosfet is an IRF3205    http://www.irf.com/product-info/datasheets/data/irf3205.pdf

Here are the main stats:
Continous drain current 80A at 100deg., 110A at 25deg,  pulsed drain current is 390A
Power dissipation , 200W
Gate to source voltage +-20

If my light is 50W, don't I have 150W left to play with? 

I did not have a heatsink on it.
Do you have to have a heat sink bolted to it always?  I thought you can use mosfets with out heat sinks at lower power levels??





27  Using Arduino / Programming Questions / Looking for tutorial on how to make a menu for my arduino, and then use buttons on: September 24, 2012, 05:59:23 am
Looking for tutorial on how to make a menu for my arduino, and then use buttons to access that menu and turn lights & motors on/off etc.

There must be a easy to understand tutorial for a noob somewhere online???
28  Using Arduino / Project Guidance / Okay, how do I control a PC fan with the LCD screen ie faster or slower? on: September 22, 2012, 09:10:03 pm
I have finally opened up my arduino and managed to easily get a 20x4 lcd screen working.

I would like to try to control say a PC fan or what ever, it does not matter what it is.  But I would like to be able to have a menu come up on the lcd screen that might say something along the lines of " speed 1,2,3,4 etc"
then be able to select which speed you want.

So I guess I would need a few push buttons to use as buttons to select which menu option to use etc.
But how do you program this?
Are there any similar projects that people have done and have lessons or instructions at all?

Peter
29  Using Arduino / Microcontrollers / Freetronics eleven VS Arduino Uno R3 on: July 19, 2012, 02:25:52 am
Is there any difference between the Freetronics eleven and the Arduino Uno R3. 

I think that before the Uno R3 the Freetronics eleven might have been a lot different, but now with Uno R3 I think they are similar?

Anyone know?

30  Using Arduino / Project Guidance / How do you use a LCD screen and program it for fan speed and display rpm? on: July 14, 2012, 01:39:29 am
I am putting together a shopping list for an arduino.  I would like to have an lcd screen that is some how connected to a dc fan.

How exactly do you have a screen showing  "Speed 10%" then when you press a small up button it then changes to "speed 20%" etc  then have like a enter button to select the speed.  And as soon
as you hit that enter button the fan speed will increase to what ever speed you select.

How is that done?  Is one particular brand/type of LCD better than others?
I read that serial LCD is easier to use as it only have 4 wires.

Then also if I wanted a temperature sensor to display the temp on the lcd is that hard to do.  Can you set up pages, so like show fan speed on page 1, temp on page 2, and on page 3 the motor speed adjustment selector.


Peter
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