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571  Using Arduino / General Electronics / Re: Old Computer Power Supply on: August 14, 2014, 12:45:28 am
That's odd.
I had to put a 10 ohm 5 watt on mine to get it to work.

I didn't try 10ohms, but yeah if it needs 500mA then 10K does seem waaaay too big. But it works....

(I do have a 10ohm one, so I might try it- it's just connected with terminal blocks so it's easy enough to swap out)
572  Using Arduino / General Electronics / Re: Old Computer Power Supply on: August 14, 2014, 12:15:24 am
@JimboZA
Could be your power supply had one already built in though.

Nope- it didn't fire up without it.
573  Using Arduino / General Electronics / Re: Old Computer Power Supply on: August 13, 2014, 11:27:14 pm
The point is to draw about 500mA

Well I just used the resistor that the article said: it (and all others I've seen) were silent on the current requirement to switch the supply on. So the info on the 500mA is good for future reference.
574  Using Arduino / Motors, Mechanics, and Power / Re: proplem in DC motor on: August 13, 2014, 11:12:48 pm
I second cr0sh on that Pololu 2130: I have one and it's excellent. Main thing about it is its size, it's tiny, and it doesn't require a heatsink the size of a barn door. Its wiring is a bit simpler than 293/298 since there's no explicit enable pin, and for speed you just pwm 1 of the 2 inputs.
575  Topics / Robotics / Re: Recommendations Needed: Hardware Suppliers on: August 13, 2014, 11:08:30 pm
For the scaffolding as you call it, Meccano (USA: Erector ?) is a good way of making up frames and stuff.
576  Topics / Robotics / Re: Recommendations Needed: Hardware Suppliers on: August 13, 2014, 11:03:19 pm
This place seems to have tons of stuff like that.
http://www.servocity.com/
Sparkfun I think is also getting into this area.
http://www.servocity.com/
altho maybe not quite as organized yet.

You pasted same link twice CR....

Here's Sparkfun for OP: https://www.sparkfun.com/
577  Using Arduino / General Electronics / Re: Old Computer Power Supply on: August 13, 2014, 11:01:53 pm
I use a 10K 10W resistor on the 5V line as shown in pic. It was convenient to cable tie it to the fan guard.
You do mean a 10 ohm resistor, don't you?


No. I used a 10K having read somewhere (no idea where, now... ) that that was the required one. I actually bought a 10R by mistake and then re-read the instructions and Lo! it said 10K so I went an got one and used it.
578  Using Arduino / Motors, Mechanics, and Power / Re: proplem in DC motor on: August 13, 2014, 10:27:58 pm
This isn't a program writing service. This is a help forum. You write the code. We help you with it.

While agreeing with that sentiment, the methods for powering motors, reversing, and even speed control are so well known that it seems a pity not to point a member to examples like this or this.

To reverse a motor you need to reverse the connections. You can either do that by hand, eg reverse the battery which is not very practical, or use an h-bridge as shown in those tutorials. You can make an h-bridge with switches. Read about h-bridges here.
579  Using Arduino / General Electronics / Re: Old Computer Power Supply on: August 13, 2014, 10:02:52 pm
I use a 10K 10W resistor on the 5V line as shown in pic. It was convenient to cable tie it to the fan guard.
580  Using Arduino / Programming Questions / Re: Writing and calling functions on: August 13, 2014, 08:43:05 am
http://arduino.cc/en/Reference/FunctionDeclaration
581  Using Arduino / Programming Questions / Re: Make It Robotics Starter Kit on: August 13, 2014, 08:18:24 am
First go to this page and click the link to support files:

http://blog.radioshack.com/2014/05/radioshack-make-magazine-launch-make-robotics/

The libraries are in the MakeItRobotics folder in the zip file.

Then read this: http://arduino.cc/en/Guide/Libraries
582  Using Arduino / Sensors / Re: Arduino with 400 button ?? on: August 13, 2014, 08:00:11 am
Quote
So im working on this project

Which project?

http://forum.arduino.cc/index.php?topic=244885.0
583  Using Arduino / Motors, Mechanics, and Power / Re: controlling DC motor via L298N with arduino on: August 13, 2014, 07:53:46 am
298 is that it can drop almost 5V if my memory serves, at high current.
According to the datasheet it drops about 1.6V to 3.7V, depending on load upto 2A
max (at which point its probably going to melt anyway)

I'm sticking with 5
584  Using Arduino / Programming Questions / Re: Make It Robotics Starter Kit on: August 13, 2014, 07:49:56 am
But did you install the library?
585  Using Arduino / General Electronics / Re: pls help me with this simple computation on: August 13, 2014, 03:14:44 am
Quote
well since we are here sir, may i ask sir the meaning of the contact rating
Rated Load
5A 220VAC
5A 24VDC

is this right as i can get a maximum contact 5A to  loads having 220V Ac supply  and
5Amax contact to loads having 24V DC supply ???

Yes, that's on the output side.

Quote
if the current running through the coil (75mA) has something to do with the relay's contact power (5Amax)

The coil and the contacts are independent: that's the whole idea of a relay.  A relatively small voltage at a low current energises the coil.... the coil is an electromagnet.... the magnet pulls the contacts closed and they in turn are connected to the load.
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