Need help sourcing Led Drivers

[zachts]

you asked about a "pot" controller.. Doesn't matter what the fan wants..
That controller is simple voltage limiter via resistance AFAICT...

you know, I have to ask this.. Why are you trying to skimp on the very thing that makes LED's so desirable?.. dimming, programming and control.. Makes no sense..
The Typhon is just a pre-programmed aduino w/ "shields" like a clock chip ect.. Not pushing it per se.. just a bit baffled..

If you get PWM controlled fans you are still back at square one...

Better than the typhon is the storm controller, about $10 more but way way better IMHO!

 

[oreo57]

Better than the typhon is the storm controller, about $10 more but way way better IMHO!

Every time I look at that one .. I lean to the Storm X.......Currently the Storm is $15 more.. Storm X about..$50 more..

 

[zachts]

Every time I look at that one .. I lean to the Storm X.......Currently the Storm is $15 more.. Storm X about..$50 more..

LOL! how many really need more than 6 channels though?.......well other than me :lolspin:

 

[perkint]

arduino pro mini ~$5
4 pots either 5kohm or 10kom, dirt cheap ($1.50 from steves leds also all over the net)
.....plus, you then have the flexibility to turn it into a controller later.......
total cost ~$9, (but then you have some shipping or just get the leds from steves also....)
Just my two cents.

This!!!

As if it was designed for the LDDs and can easily update from manual dimming by adding a $1 RTC and have it control the LEDs automatically to add sunrise, sunset, moonlights, etc.

Tim

 

[R_Mc]

I'll have to read up on the arduino option. Any links to more detailed instruction would be very helpful.

but at the very least - it looks like I'll at least need a FTDI breakout board, breakaway headers:
https://www.sparkfun.com/products/9873 $15
https://www.sparkfun.com/products/116 $1.50

Which brings me back up to the mid $20's and about the same cost as just buying 4 pwm controllers again.

 

[R_Mc]

Does the arduino come with any code on it? Would it have to be modified?

I assume if code needs to be written it would just be to take a voltage input on the analog pins controlled by a pot and translate it to the appropriate duty cycle...but I have never programmed one of these before.

 

[oreo57]

Does the arduino come with any code on it? Would it have to be modified?

I assume if code needs to be written it would just be to take a voltage input on the analog pins controlled by a pot and translate it to the appropriate duty cycle...but I have never programmed one of these before.

Well it is a bit more complicated ..
https://www.boostled.com/Articles.asp?ID=250

 

[perkint]

If all you want is manual dimming, it is as simple as setting the PWM in proportion to the input voltage from the pot, yeah. In fact, you could probably combine reading from the input, calculating the PWM value and setting it into one line per channel (using the map function).

And no - you don't need the FTDI with the nano - for less than $5 you can get one with mini USB on board

Tim

 

[zachts]

I'll have to read up on the arduino option. Any links to more detailed instruction would be very helpful.

but at the very least - it looks like I'll at least need a FTDI breakout board, breakaway headers:
https://www.sparkfun.com/products/9873 $15
https://www.sparkfun.com/products/116 $1.50

Which brings me back up to the mid $20's and about the same cost as just buying 4 pwm controllers again.

arduino nano or uno can be had for under ~$8 on ebay and have the usb FTDI built in. Just got some uno's in the mail today that were only $4.50, but they came on the slow boat from china so took a month to get them.......

 

[zachts]

Does the arduino come with any code on it? Would it have to be modified?

I assume if code needs to be written it would just be to take a voltage input on the analog pins controlled by a pot and translate it to the appropriate duty cycle...but I have never programmed one of these before.

I posted the code you need for manual dimming on the first page in a zip file. all you do is plug the arduino into your computer, open the arduino IDE (program you download for free) and upload the code. then just wire things up and your done in under 10min if you solder fast

 

[perkint]

Not sure why, but these don't seem to come up on ebay.com (but do on ebay.co.uk):
http://www.ebay.co.uk/itm/Mini-USB-...al_Components_Supplies_ET&hash=item2348a89cc5

Tim

 

[R_Mc]

Thanks Zach - missed that & reading through it now.

So I will have to use a 5V power supply over the pots... I feel like I also need to current limit this somehow - when I dim the lights down all the way I will get 5V over...maybe 10 ohms or 500ma which seems pretty high...

Should I add a 1k ohm resistor in series (on the high side) with each of pots to ensure that the current will not exceed 50ma?

Then change the code
eg from: analogWrite(3, read1/4);
eg to: analogWrite(3, (read1 +93)/4);

The +93 being that the analog input will now be between 0V and ~4.545V which equates to an input value of 0 to (4.545*1023)/5=929.907
1023 - 929.907 = 93.093

 

[zachts]

Thanks Zach - missed that & reading through it now.

So I will have to use a 5V power supply over the pots... I feel like I also need to current limit this somehow - when I dim the lights down all the way I will get 5V over...maybe 10 ohms or 500ma which seems pretty high...

Should I add a 1k ohm resistor in series (on the high side) with each of pots to ensure that the current will not exceed 50ma?

Then change the code
eg from: analogWrite(3, read1/4);
eg to: analogWrite(3, (read1 +93)/4);

The +93 being that the analog input will now be between 0V and ~4.545V which equates to an input value of 0 to (4.545*1023)/5=929.907
1023 - 929.907 = 93.093

Most All arduino boards will have an onboard 5v source available so you shouldn't need an extra supply.

ASFAIK you only need limiting resistors when using the arduino pins as outputs. In this case they are configured as input and only reading voltage so not much current will be flowing. if using voltage from a tiny on board regulator like on the pro mini that I use for lots of stuff the limiting resistor might not be bad to help protect the regulator in event of an accidental short (then a gain most regulators have internal over current and over temp protection built in)

Compensating for the resistor if you used it isn't really necessary in this case. You only loose a few points of resolution but the output pwm is still going to be 0-255 or 0-100% brightness from the LEDs. the code you edited would result in not being able to hit 0% brightness and would cause the signal to roll back over to zero and start dimming back up as you turned the pot up to what would be near 100% (if you try to write a value above 255 it rolls over unless you add a line of code that limits this by saying any value over 255 = 255 etc.

 

[R_Mc]

Thanks you're totally right I had a mind melt and forgot that the resistance would always be 10k across the pot for the 5v pin.