next topic »

[on:]

OK i don't even know that arduino is capable of this but if not maybe someone can tell me what microconrtoller would be able to do this to start me in the correct direction.

Ok basiclly I will have a coil that has resistance of course and a DC power source and LCD dispay and 2 buttons for up and down.

The LCD displays a number that reprsents the users desired wattage and the user can adjust up and down from like 5-15watts

The chip has to first read the coil resistance and then do the following calculation
W= User inputed number
R = resistance of the coil
V² = DC Voltage squared
V =     √  of V²


W/R = V²

√V² = V


The answer is the amount of voltage that gets delivered to the coil. it has to loop incase the user raises or lowers the Wattage on the fly.


I hope i made this understandable I don't know how else to explain it.

Any info you can provide would be greatly appreciated.

Mike

[Reply #1 on:]

The resistance is always going to be the same so why not measure it first and incorporate the value into the program. Then all you have is a programmable voltage output. You will need some external hardware to control this as the arduino can only output up to 5 volts directly, as can virtually all other micro controllers.

[Reply #2 on:]

This project will have a replacable coil from 1.5 ohm - 4.5 ohms so it definitly will have to read the coil. Is that posible with an arduino?

I didn't know that the max voltage was 5v. is there a booster board that can maybe be installed along side that might give 2.5 volt boost to whatever voltage is applied? I think i have seen a TI chip that does this i will have to look again.
The range i am looking to achieve is 3- 7.5 volts depending on the user input and reading of the coil.

[Reply #3 on:]

Is that posible with an arduino?

Yes you need to apply a known voltage to it and measure the current. Normally this would be done using a small resistor and measure the voltage across it. However as you coil is already in the 1R region the currents involved would be huge. As well as only supplying 5V and arduino output can only source 20mA of current and this is more than most micro controllers. You would be much better off trying to encode some sort of key so the controller knows what coil is used, or a coil code to enter.

is there a booster board that can maybe be installed along side that might give 2.5 volt boost to whatever voltage is applied?

No.

Anything you do you will have to design yourself. It looks like you need to supply a current of 2A with a variable voltage of 3 to 8V. Such things are available commercially but cost 100s of $. It is not a simple thing to design.

Your problem is not just voltage it is current capability as well.