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16  Using Arduino / General Electronics / Re: Arduino Mega, Screw (Terminal) it on: November 26, 2012, 06:26:57 pm
I'll take one. I sent you a PM about it.
17  Using Arduino / Motors, Mechanics, and Power / Re: 12V PC fan voltage control on: November 17, 2012, 09:05:22 am
Ok, so could I do this circuit with a TIP120 Darlington?

I'd imagine the circuit would be Pin 6 to Base, Fan Ground to Collector, Emitter to Ground? Would I need a pull-down resistor to Ground on the Base?
18  Using Arduino / Motors, Mechanics, and Power / Re: 12V PC fan voltage control on: November 17, 2012, 12:13:14 am
I'll give Tuxedo's transistor setup a try... Should work. The PWM freq. from the Pololu motor controller was too high, that's why the fans didn't respond. PWM would actually be the preferred method so I can set different fan speeds for different temperatures.

** What radioshack friendly transistors could I use to setup a pwm circuit like the one Tuxedo mentions
Quote
Pin 6 goes to a 1k resistor which goes into a bc237b base. bc237b collector to +5 and emitter to a 1k resistor, to bd135 base. Fan red wire to +12v, black to bd135 collector. bd135 emitter to gnd.
?
Again, sorry for lacking so much electronics knowledge lol I knew more a few months ago when I was learning something new every day, but then I stopped working on Arduino projects for a few months and now I'm back to stupid.
19  Using Arduino / Motors, Mechanics, and Power / Re: 12V PC fan voltage control on: November 15, 2012, 02:47:21 pm
Thanks dc42, I know of those pwm-capable fans, but I'm prototyping and I already have a bunch of fans laying around from a previous project and I'm trying to not blow my budget with buying things I already have. Any thoughts on how I can just switch the voltage going to them? I'm using a PC power supply, so I'll have 5V and 12V readily available and it would be great if I could switch between 5v and 12v rather than doing a variable control.

** I thought brushed motors were more difficult to control through PWM than brushless... Maybe they are brushless then, I'm not sure. I just remember that I tried it before and they didn't slow down or respond to the PWM control through the motor controller at all.
20  Using Arduino / Motors, Mechanics, and Power / Re: 12V PC fan voltage control on: November 14, 2012, 07:02:32 pm
That's my thoughts... Lower the PWM freq. or I might use a different way.
21  Using Arduino / Motors, Mechanics, and Power / Re: 12V PC fan voltage control on: November 13, 2012, 10:52:56 pm
If I use a 5v relay with both N.O and N.C outputs, I can put a pot on one of the outputs... Any idea's for doing this solid state, such as a transistor or mosfet that has 2 separate outputs depending on control signal?
22  Using Arduino / Motors, Mechanics, and Power / Re: 12V PC fan voltage control on: November 13, 2012, 07:58:44 pm
I fooled with an array (4) 120MM fans on a full H-Bridge motor controller (Pololu brand) and the PWM wouldn't work... Maybe I needed to set the PWM pulse speed lower (less than the 20kHz)? I don't know, but I'd just like a simple way to switch the supply voltage lines without having to rig up a bunch of relays or anything eccentric like that. Maybe a 5-pin relay or something? Mmm... The fans will always be on, so it's not like I need 12V, 5V and Off... They could always run at 12V and be switched to 5V when needed.
23  Using Arduino / Motors, Mechanics, and Power / 12V PC fan voltage control on: November 13, 2012, 06:05:02 pm
Hi, I am looking for a simple straight forward way to control the voltage to a PC fan with a 12VDC brush motor. Would like to be able to turn the fan on low speed (5V input) with Arduino pin set to low and high speed (12V) when the pin goes high...

Thanks for the input guys and sorry for being such a damn newb lol
24  Using Arduino / Motors, Mechanics, and Power / Re: DIY motor driver on: September 29, 2012, 12:23:49 pm
Quote
Could you please point me in the right direction for finding a mosfet that can switch 9+ amps?


https://www.sparkfun.com/products/10213


Nice, thanks!!
25  Using Arduino / Motors, Mechanics, and Power / Re: DIY motor driver on: September 29, 2012, 12:22:13 pm
Could you post a link or picture of your brushless motors. Most such motors don't work with a H-drive controller  which are designed to work with single winding motors.

Lefty

They're actually not motors, they're thermoelectric coolers (Peltiers).
26  Using Arduino / Motors, Mechanics, and Power / Re: DIY motor driver on: September 29, 2012, 09:40:26 am
Could you please point me in the right direction for finding a mosfet that can switch 9+ amps? I went over my design and realized that I really only need PID control over 2 motors now and the rest can be done by switching the devices (they're solid state) on/off when they hit their target values.

Thanks!!
27  Using Arduino / Motors, Mechanics, and Power / Re: DIY motor driver on: September 29, 2012, 06:43:34 am
Thanks, I didn't think about looking there for chips! I have some of their prebuilt motor driver boards and love them.
28  Using Arduino / Motors, Mechanics, and Power / DIY motor driver on: September 28, 2012, 11:48:25 pm
Hello, I need to control 6 brushless motors each taking a max of 9amps at 12.5VDC and 2 brushed motors taking a max of 3amps at 12.5VDC. Typically I would just buy a pre-made H-Bridge, but since I need to control so many different channels it gets expensive... I need to be able to run the brushless motors in fwd/rev and PWM for PID control through Arduino... The 2 brushed motors are 12v 120mm PC fans and I'll be controlling the speed of those based on temperature through PID.

Any advice on how to go about this would really be appreciated. I'm not even sure what chips to use, etc. I found a bunch of cheap Chinese controllers on eBay but they use very low powered ST L298 chips.

Thanks!
29  Using Arduino / Programming Questions / Re: DS3234 RTC & Alarms on: December 17, 2011, 11:06:37 pm
jwatte, thanks for the help. Understanding the software is my problem. I tried your suggestion and it worked perfectly. Thank you very much!

On a funny note, when I first tried your suggestion, set pin 13 to output, etc, it wouldn't work... what the hell... After a few minutes of frustration I look down at my Arduino board and realize that I'm using Pin 13 for SPI CLK function lol. That's how it goes when you're operating on 5hrs of sleep... Time for bed before my brain melts smiley
30  Using Arduino / Programming Questions / Re: DS3234 RTC & Alarms on: December 11, 2011, 08:59:58 pm
I'm still confused lol. If I try to type in if(hour == etc...) the compiler comes back and says that "hour" was not declared in this scope.

This code prints the correct information to the serial port but I just don't know how to interface with it to use what it's printing...
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