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1  Using Arduino / General Electronics / Re: Charge mini battery? on: October 06, 2013, 02:47:21 pm
3.7V looks like Li/ion battery, you need a special charger for that, isn't it a standard micro or mini USB socket? The device probably already has all the electronics needed for safe charging, see what's cheaper, a new power plug or a li/ion charger.
2  Using Arduino / Motors, Mechanics, and Power / Re: Using official Motor Shield with Arduino Uno on: September 18, 2013, 09:06:51 am
From the schematic, these pins are just pass through, they allow stacking another shield that would use these pins.

So yes you can cut them if needed to fit the shield, the motor driver chip itself doesn't use them.
3  Using Arduino / Motors, Mechanics, and Power / Re: VEXTA PH256M-33-C3 Step motor on: July 07, 2013, 09:00:18 pm
unipolar/high voltage usually mean older motor/technology.

With steppers you can actually go faster whith lower voltage motors using current limiting drivers with higher than needed power supply voltage (for example a 12V supply with a 2V motor). Current rises faster because the motor inductance is lower. The faster you try to step, the less time there is for the current to rise. When the current is not high enough because you're stepping too fast, the torque is too low and the motor looses steps or stalls, so it's important to have the faster current rise possible.

So what you want for fast steppers is low voltage/low inductance bipolar motors.
4  Using Arduino / Motors, Mechanics, and Power / Re: Managed to damage a power supply but can I fix it? on: July 02, 2013, 08:43:57 pm
Looks like you're almost good to go, replace the capacitor. If you don't plan to use the -5 output just leave it as is.
5  Using Arduino / General Electronics / Re: H-Bridge on: July 02, 2013, 11:24:01 am
It'd be better to add flyback diodes as well, 1N4001s would be ok.
6  Using Arduino / Motors, Mechanics, and Power / Re: Motor Controller Current Limiting on: July 02, 2013, 11:14:57 am
Man that's rather heavy stuff, no wonder you need that sensor.

You can't really compare that to the motors those shields are supposed to drive.
7  Using Arduino / Motors, Mechanics, and Power / Re: Motor Controller Current Limiting on: July 02, 2013, 08:38:42 am
I may be mistaken but this sensor seems to handle 300A, are you using a 15KW motor?

Else you probably won't get enough accuracy unless using a high quality ADC.

Current regulators on shields usually have a shunt resistor and just measure the voltage accross this resistor.
8  Using Arduino / Motors, Mechanics, and Power / Re: Managed to damage a power supply but can I fix it? on: July 02, 2013, 08:29:30 am
Hard to tell, could be just a diode, if there's no regulator for the -5V, it's probably a 5V zener.

what's the voltage you get get on the input of the 29M05 (left pin when looking at the front)? should be between 6 and 16V, if it's lower than that, something else broke before the regulator.

9  Using Arduino / Motors, Mechanics, and Power / Re: Managed to damage a power supply but can I fix it? on: July 01, 2013, 08:50:57 pm
what kind of regulators are they?

how do you know it's a zener and not a standard diode?
10  Using Arduino / Motors, Mechanics, and Power / Re: Motor Shield Power HELP!! on: June 30, 2013, 09:45:55 pm
Well you could use a 4.8V battery pack (4 NiMH) or 3 1.5V standard batteries.
I think you could also use a much higher voltage pack and use the pwm to limit the output voltage (for example if you use a 12V battery you should be ok if limiting the speed to 95 because the pwm should chop the 12V to about 4.5V) but you better make some tests to make sure you get the right voltage.
11  Using Arduino / Motors, Mechanics, and Power / Re: Nema 17 and 4cm fan on: June 30, 2013, 09:30:59 pm
Well nema 17 means 1.7 inch that's 4.3cm, no wonder the distance between holes doesn't match.
12  Using Arduino / Displays / Re: HD44780 contrast pot and BL resistor question on: June 30, 2013, 09:28:12 pm
No, turning the pot should really adjust the contrast, did you connect the 3 pins just like on the datasheet?

From the datasheet, it looks like the backlight voltage is 5V so you shouldn't need any resistor, just use a pot to test just in case if you feel bad about connecting VCC directly on it.
13  Using Arduino / Motors, Mechanics, and Power / Re: Managed to damage a power supply but can I fix it? on: June 30, 2013, 10:15:09 am
If the regulators are 7805 and 7905 you may be able to replace them.
But you probably have something shorting the outputs, pulling the voltage down because the current must be higher than expected, check for electrolytic capacitors and see if removing them helps (and replace them of course)
14  Using Arduino / Motors, Mechanics, and Power / Re: Futurel Step_Shield 8190 Problematics on: June 30, 2013, 10:08:11 am
Well I don't have this shield but from the schematic I would:
Set the Vmot jumper to external, all the other jumpers to D5-D10.
The way it works is you have to use D2,D3,D11 and D13 to drive the shift registers on the shield to set the stepper drivers.
You have to set /Sleep and /Reset to 1, MS1-3 to the stepping mode you want (for example 010 for 1/4step), /En to 0 then use D8-D10 to set the direction and send pulses on D5-D7 to step the motor.
I'd start by writing some code that can control the shift registers before connecting anything on it and when it's working just connect the motors and the power supply.
Good luck.
15  Using Arduino / Displays / Re: How to display "big" numbers on a character LCD on: June 28, 2013, 10:15:33 am
I did a quad size font by cheating a bit on the needed glyphs to prevent redefining them:
http://forum.arduino.cc/index.php?topic=150227.msg1128016#msg1128016
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