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1  Products / The Arduino Starter Kit / Re: PDF of book that comes with the Arduino starter kit on: Today at 12:42:55 pm
I blame Wired magazine for the whole "black text on dark blue" and "light grey text on medium red" thing. I see a lot of websites that are difficult to read.

I don't want color behind text. Just make it black text on white! I don't need style to obscure the information.
2  Using Arduino / General Electronics / Re: Ohm's Law. on: Today at 12:41:07 pm
Careful not to read bad attitude in where none may exist.

I'm finding the discussion of the whole 1023 vs 1024 thing very interesting.
3  Using Arduino / General Electronics / Re: Motorized rotary switch on: August 29, 2014, 05:50:01 pm
Can you sketch something? I can only see how that would save one relay. IE, 8 inputs. Two to each of 4 DPDT relays, reducing it to 4 lines.

Output of a pair goes to another DPDT relay, reducing it to 2 lines.

A last relay selects between those two. But that is 8 inputs and 7 relays. But at the cost of requiring more than one relay be activated for some inputs, increased complexity, and a bunch of connections in series.

I am not picturing what you are seeing. Or are you talking about mono with DPDT?
4  Using Arduino / General Electronics / Re: Motorized rotary switch on: August 29, 2014, 12:53:20 pm
Make sure the contacts are rated for a suitable level of current.
5  Using Arduino / General Electronics / Re: Motorized rotary switch on: August 29, 2014, 12:52:16 pm
I have never heard of speaker wires being called "HP lines". Google has no relevant matches in the first three pages.

A stepper motor on a 16 throw, 2 pole switch. Or a set of 16 relays.
6  Using Arduino / General Electronics / Re: PWM drive MOSFET not working properly. on: August 29, 2014, 12:48:15 pm
Schematic?

How would what happen?
7  Using Arduino / General Electronics / Re: LM324 output to Arduino interrupt not working correctly (with schematic) on: August 29, 2014, 10:40:55 am
That second-to-the-last Op Amp should be a comparator. There are many reasons why it is a bad idea to use an Op Amp as a comparator. One, as has been pointed out, is that this particular Op Amp cannot pull all the way down to the negative supply rail (ground, in this case).
8  Using Arduino / General Electronics / Re: Will powerful Capacitor between 5v and Gnd damage the voltage regulator? on: August 29, 2014, 10:36:28 am
A big problem: Put those 10mF caps on the 5V line, and as CrossRoads says, you need a diode across the regulator Input/Output to prevent the regulator from being damaged by having voltage on the Output when there is less voltage present on the Input.

Do you see the problem? Now the 10mF caps are simply being dumped back into the power supplying the pump.

Better:

Main voltage
Diode
10mF caps
Arduino unregulated voltage input

Then when the pump drags down the power supply voltage, the diode prevents the 10mF caps from being discharged there, while they continue to supply voltage for a short time to the Arduino's voltage regulator.
9  Using Arduino / General Electronics / Re: using a buck converter as constant current source on: August 28, 2014, 03:56:04 pm
http://www.onsemi.com/pub_link/Collateral/LM358-D.PDF


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Look up with LM358, output are bipolar and output can not be lower than about 1 volt over GND.

Page 4 of the PDF above says that the output can go down to 5mV typical, 20mV max. But that doesn't really matter, we aren't asking the output to go that low.

The inputs are rated to go down to the negative rail, ground in the case of a single supply.

Both inputs and outputs can't go within about 1.5V of the positive rail.

In any case, simpler to use a purpose-built constant current switch mode LED driver, unless you have the other parts and can't easily get such an IC.

10  Using Arduino / General Electronics / Re: using a buck converter as constant current source on: August 27, 2014, 05:48:01 pm
The open loop gain of the LM358, in V/mV, is 25 minimum, 100 typical. So Av is 25000 to 100000.

Page 4:
http://www.onsemi.com/pub_link/Collateral/LM358-D.PDF

There is no such thing as a 0 ohm line. Even a short chunk of wide PCB track has resistance.

Since it is using that track as a current shunt to measure load current, you must pay careful attention to where everything is wired to ground.
11  Using Arduino / General Electronics / Re: using a buck converter as constant current source on: August 27, 2014, 04:39:09 pm
I've been thinking of using the MC34063 in buck mode as a current regulator, by using the correct value of current limit resistor. That is a peak current limit resistor, though.

The LM2596 circuit needs to be modded similar to how you add current limiting to a 780x regulator.

http://images.elektroda.net/65_1301577300.gif
12  Using Arduino / Project Guidance / Re: Please help anybody on: August 27, 2014, 02:07:19 pm
I was thinking specifically of tip number 6.
13  Using Arduino / Project Guidance / Re: Please help anybody on: August 27, 2014, 01:45:45 pm
http://arduino.cc/forum/index.php/topic,148850.0.html
14  Using Arduino / General Electronics / Re: logic level for Arduino on: August 27, 2014, 01:44:31 pm
A meter cleans up a lot of the noise. That could be a fairly noisy 1.2V, and still show up as "stable" on a DMM.
15  Using Arduino / General Electronics / Re: The right parts to make my project smaller.... on: August 27, 2014, 11:56:27 am
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Okay well whatever I'm done, It works the way I have it, it has been working for the last month so i;m not going to change it.

Quote
It keeps being repeated "post your code" "post your schematic" but I already stated --THEY DON'T EXIST YET!!!

I won't bother you any more.
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