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16  Using Arduino / Project Guidance / Re: Clean and energy efficient LED dimming on: February 14, 2013, 09:04:38 am
What is over-kill?
I meant the Highly Efficient 0-100% LED Dimmer; it's an interesting project, but is it necessary? You must be the judge of that. It is very easy to get carried away with specifications. I would imagine that one of your main criteria is long life and relative cheapness. It's akin to buying a hybrid car, I've driven a few, they are okay around town, they don't save the environment, they cost a lot to run and to purchase. The product needs to fit the requirements.

Selling the house my parents build stone by stone with there own hands - never ever smiley
Lucky you, I'm envious  smiley-mr-green

I have no lux meter.
But what about the 4.5Volt i always have?
Why does the Mosfet not totally turn off?
If your fet is partially on, then you may be seeing a small voltage, they require very little leakage before they start to conduct. Try disconnecting the gate from the port and tying the gate with a resistor and see if you get the same result.
My suggestion was to use a digital (SLR) in place of a LUX meter as a crude replacement. Illuminate a scene with your LED and check that the exposure changes as you continue to increase the PWM. Maybe your source voltage is too high?
You may need to play with the position of the illumination and objects in the scene to get a full range effect. - just an idea.
To see how "unreliable" (fabulous) your eye is in this situation, take an exposure reading indoors in a bright room and then try the same outdoors.
As to flicker, I would think that the 490K of the Arduino ought to be okay, I can't report that it has ever bothered me when playing with LEDs, But I have not illuminated a room. I have to say that VW tail-lights annoy me, I don't know what frequency they cycle at, but I find the light trails as I move my head distracting.... Maybe they are just flashbacks?
17  Using Arduino / Project Guidance / Re: Clean and energy efficient LED dimming on: February 14, 2013, 06:33:41 am
My first test LED lamp is here.
There is something i forgot. They work with AC and DC and it doesn't matter
where you connect positive and negative. So there must be some kind of electronic inside the lamp.
Somebody know how they work? How does this effect the dimming circuit i need to build?

If i switch from "PWM 1" to "0" it really needs long until my multimeter goes down to 4,5V.
Sounds like you may have a capacitor in there.
As to "brightness" your eye's sensitivity may not see much difference between 50 & 100% Have you used a lux meter (digital camera exposure meter?  smiley-cool )
18  Using Arduino / Project Guidance / Re: Clean and energy efficient LED dimming on: February 14, 2013, 06:28:09 am
Looks like over-kill to me, but...

Test cable runs first and be wary of running 12 near 240 (they should NOT share the same conduit) crossing at 90deg is preferable.

Everything here is 230 Volts. I don't want that anymore.
If i make it 12 Volt i save energy and can power it one day with photo voltaic.
If you come to sell your house, will this effect the price? Will you want the availability of mains in the future.
If you have a ring main for the lighting, can you use the existing switch wires and place your 12V controllers above the lights, so effectively re-using the cables and not worrying about sending 12 over long distances? This would allow you to revert to 240V at any stage.
19  Using Arduino / Project Guidance / Re: Can you sent data through the human body?? on: February 14, 2013, 06:12:07 am
...or you already know somebody else has solved the problem and your "project" will just be to copy whatever they did, or you hope you're going to find that somebody has already solved it and you can just copy their solution. The first case is the one which would earn you most credit but your professed lack of technical skills seem to rule that out....
Very much agree, but as a matter of interest, my boy is at uni and every piece of work is electronically checked for plagiarism, both external to the set piece (the world) and locally (the class) and this is used as part of the mark scheme. Although this can be rather stupid! When he was returned his first piece of work marked at 89% He found he had lost that 2% for using the same column heading as someone else! He has also found that handing in your work first puts his class mates at a disadvantage, seems a nasty way to earn a 1st! But does get the work in on time smiley-wink
20  Using Arduino / Project Guidance / Re: Can you sent data through the human body?? on: February 14, 2013, 06:02:27 am
Thinking aloud. You can easily use very high impedance sensors that that can be made with a simple CMOS gate or two and some 1 to 10 Meg resistors. So a hex inverter could be used to both make the input of a sensor and say a monostable to give a 'clean' buffered output. A label button could offer a high frequency source an next to zero current that could be gated by a data stream, more CMOS.

I think more info is required. I have to agree with other posts regarding graduation projects and safety.

I understand that Texas is keen on such development although they have not been very successful to date.... depending how you measure success.
21  Using Arduino / Sensors / Re: problem about sensor hc sr04 on: February 14, 2013, 05:43:38 am
long r = 0.034 * duration / 2;
That could be simplified.
long r = 0.017 * duration;

I've not run the code but it looks about right.

What distance are you trying to measure, 2 to 3 cm is about minimum, and the supposed maximum was probably obtained in an test chamber - or I have edge of the bell curve devices smiley-wink

many code snippets give...

digitalWrite( triggerPort, LOW );
17    delayMicroseconds( 1 );
18   //invia un impulso di 10microsec su trigger
19   digitalWrite( triggerPort, HIGH );
20   delayMicroseconds( 10 );

Just read your post again, are you suggesting that it is pre-triggering? (reading the outgoing chirp?) I would think that was unlikely, although your device may be faulty. you could add a few uS delay before the pulseIn()
I've not hooked a scope to one of these yet, but I do note that there are several models and some can be set to single pin mode - do check your device.
22  Using Arduino / Programming Questions / Re: speedometer code using to photosensors for arduino on: February 14, 2013, 05:28:08 am
You may also want to colour your "raindrop" with dye (food colouring?) so that it obscures the beams.

What do you have, what do you know? you can purchase optical sensors that may work if you can get your drop to fit....

Here available from ebay of course.
23  Using Arduino / General Electronics / Re: daisy chaining 74HC595's on: February 14, 2013, 05:13:44 am
Fortunately, 74HC devices are supposed to meet certain specifications

Hence my suggestion to read the DS. I once became very unstuck when a bucket load of chips turned up with NC where there was supposed to be an inverted output! Once bitten....

FYI Ruffsta, many chips are supplied without (or unreadable) part numbers, but they will usually have the manufacturers name/logo (logos are another learning curve) (hint, dampen with a whetted finger tip and angle to light)

I would suggest (to anyone who hasn't yet) getting hold of some data sheets of components you are familiar with (LEDs, Transistors, even Resistors) because it does take a while before you "get your eye in". They are filled with information that is of little interest to the average punter unless you want to push the envelope. You will find details of the package, soldering criteria, operating and storage minima & maxima, more graphs than you can shake a stick at, exemplar circuits, test circuits. But you will also find pin-outs, application notes, sometimes circuit layout advice (more so for high frequency, crystals/resonators etc.), de-coupling advice, table of operating voltages, source/sink current, operating and quiescent current etc. PRINT THEM OUT, write all over them, they are your best friend, a well fondled data sheet should have coffee rings and dog ears. If you go though my filing cabinets and pull job folders, you will find data sheets by the score! You have to learn to sort the wheat from the chaff.

Some slightly off topic advice that will pay dividends...
Breadboards : Treat them with love and care, a damaged board will cause you grief and have you chasing your tail.

Soldering Irons : Forget them! Get a soldering station! I just picked one up from ebay for a few quid for my son. Ensure that it is temperature controlled (not just variable voltage) 40-60W with a selection of tips, but I personally hardly ever use anything other than a fine pencil tip.
You could of course make one using an Arduino, but seriously, for the money....
Again, treat with love! A tinned tip is a happy tip. Keep your sponge damp, use good quality solder and use the lowest temperature that allows you to solder confidently. Cleanliness is next to shinieness!

Sarcastic Hint: If you were supposed to carry the solder to the joint on the tip of the iron, they would be equipped with little ladles! If your iron has a little ladle, it's past time to change the tip smiley-wink

One last tip: Break your project down and joy it! If daisy chaining 20 chips, first prove that you can drive one, that it does everything you want, then two, again, test it! Then twenty, you will find success will be matter of fact, not a rarity and the same goes for your code, break it down in to simple, testable blocks. And don't just copy, understand! edit, fiddle, play.

Oh, and have fun!

24  Using Arduino / General Electronics / Re: daisy chaining 74HC595's on: February 13, 2013, 04:05:14 pm
Kama to JoshD

What a great shame smiley-sad I hope his son is not put off, nor indeed Ruffsta himself. Maybe after he's had a think he'll come back, maybe with a new alias, chill out and enjoy what he's doing?

Not really wanting to dwell, but I have to say that after the number of posts statement I went off and looked at his posts. I'll not comment further.

It can be very frustrating when starting any new hobby, but nothing pays off like getting down and dirty with the basics. Learning how to find info is probably one of the most useful things to learn. You struggle for a while then all of a sudden you're no longer the new boy, and there you are, helping people.

What encourages me the most when helping people, is evidence that they are helping themselves, and the odd please & thank you goes such a long way.

I have to say that I've not come across another forum with so many angry members nor as many new members who approach the subject with so much over inflated optimism. I'm not saying that the latter is a bad thing, but peeps are brought down to earth with a bump when their overly complicated first project fails.

25  Using Arduino / General Electronics / Re: daisy chaining 74HC595's - conflicting images, confused as heck! on: February 13, 2013, 08:36:28 am
Well... It's probably the best advice you can have, and I (used) to design for a living, I just do it for fun now; what about you?

ALWAYS go to the manufacturer because many manufacturers have to produce variants to get around patents or to give their product an edge.

What you are really asking, and why you are poopooing the youtube video, it to have the design handed to you on a platter!

The manufacturer will provide you with ALL the information that you need.

Admin, can you please bump up my post rate, it's too low for some people. TY
26  Using Arduino / General Electronics / Re: daisy chaining 74HC595's - conflicting images, confused as heck! on: February 13, 2013, 08:16:32 am
I would go to the MANUFACTURERS data sheets for the correct method - and then upload your own youtube vid smiley-wink
27  Using Arduino / Motors, Mechanics, and Power / Re: controlling two transistors with same port on: February 13, 2013, 07:55:45 am
Nice drawing smiley-wink
28  Using Arduino / General Electronics / Re: error on power supply on: February 04, 2013, 08:24:52 am
As said below by Docedison, just rename the net. Any number of components may have 'strange' pin assignments that meet the designers requirements rather than yours smiley-wink
29  Using Arduino / Motors, Mechanics, and Power / Re: converting astable multivibrator for DC motor on: February 03, 2013, 05:55:50 pm
Are you maintaining the swing of a pendulum?
If so don't forget that a pendulum will have a resonant frequency dependent upon it's length.

Replace the LED with an LED opto-coupler on either the Arduino or the circuit below.

How many wires does your printer motor have?
30  Using Arduino / Sensors / Re: X-Ray detector/sensor on: February 03, 2013, 05:26:28 pm
Laughed so much I choked! smiley
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