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1  Community / Bar Sport / Re: optical power lines? on: September 30, 2014, 12:25:15 am
cooking people is going to be a problem with any wireless energy transfer scheme that has a significant power density. 
That is what I was implying. High power, high frequency, RF or high power laser light will do that.
They could put the laser beam into a protective metal tube or two...they could raise the tubes on towers, for safety...have a grid of them to supply power throughout the country...
2  Community / Bar Sport / Re: Poll. Which are the safe frequencies? on: September 30, 2014, 12:00:38 am
Well most people don't stand under voltage lines...
Some people live, sleep, eat and work under them.  If your home happens to be under a 400KV line, you have little choice.
3  Using Arduino / General Electronics / Re: motor and L293DNE problems on: September 29, 2014, 11:48:42 pm
293, Arduino and motor power must all have the same ground.

The diagram shows none of the 4 GND pins in the middle of the 293 connected.... I guess they must be though, else your meter won't show 9V output.
Did you miss the dark blue connection on the diagram?
4  Using Arduino / Programming Questions / Re: DNA computing? on: September 29, 2014, 11:35:01 pm
But sequencing the DNA, in itself, is not a casual task for a humble door lock.
How would you get the sample?
Prick your finger and smear the blood? ...ouch!
Spit on it?...yuk!
Other bodily samples that I won't go into here? ...even more yuk!
Pull out a hair and feed it in? What happens when your visitor is bald?  smiley-mr-green
5  Using Arduino / Programming Questions / Re: Adjusting simple (so it should be) shift register coding for a different result on: September 29, 2014, 11:14:36 pm
Goal: I would like the  LEDs to light all the way (1-8) with the speed of the servo and reverse as the servo slows down and reverses.
Firstly, I would use an odd number of LEDs so that the centre one is lit even when the servo is stationary. In fact, it would always be lit. Instead of looking at the speed of the servo, it would be easier to determine how far away from it's target position it is. You know the position it's in (= the current position). Lets call it curPos. And you know the position you want it to go to (= target position). Lets call it tarPos. If curPos < tarPos the servo will be going forwards and if curPos > tarPos the servo will be going backwards.  tarPos - curPos will give you the distance to be moved forwards and curPos - tarPos will give you the distance to be moved backwards, so you can calculate the number of LEDs to be lit. You'll need to update curPos as the servo moves nearer to the target position. When curPos == tarPos all the LEDs, except the centre one, will be off. You could use a tricolour LED for the centre one and have it showing white when the servo is stationary and red when it's moving.
If you agree that that is the way you want it to go, we can start thinking about the programming.
6  Using Arduino / Project Guidance / Re: spdif (toslink) switch on: September 29, 2014, 10:01:03 pm
basically like this (sorry for late reply)

i been reading about mux looks like it will do what i need but cant find a digital one with enough inputs
Most analog MUXs will handle a digital signal, as it's exactly the same as a 0 - 5V square wave analog signal. The maximum frequency and peak-to-peak voltage is what you need to look out for.
7  Using Arduino / Project Guidance / Re: Apartment Door Unlocker on: September 29, 2014, 09:28:50 pm
You're negating the security of the system. It'll let anyone into the building who presses your button, even a murderer!
Does your landlord approve of this?
Does his insurance provider approve of this?
Does the local Police's Crime Prevention Officer approve of this?
8  Community / Bar Sport / Re: Every Circuit.... on: September 28, 2014, 10:09:10 pm
Closed it and reopened it. It started immediately!
9  Community / Bar Sport / Re: Every Circuit.... on: September 28, 2014, 10:01:05 pm
EC's a nice idea but, so far it's been loading for 5 minutes, and shows no sign of being done. smiley-mad
10  Community / Bar Sport / Re: optical power lines? on: September 28, 2014, 09:50:46 pm
Converting light to electricity currently maxes out at about 35% efficient, and most electricity to light mechanisms are not so good either.  High power lasers tend to be especially inefficient.

But the whole solar power satellite scheme was going to use masers, so the idea is sound.  (maser is to microwave what laser is to light.)
Wasn't that idea shelved because of the possibility that people could get cooked if the satellite went even slightly out of kilter?
11  Using Arduino / Project Guidance / Re: Vehicular emissions sensors ? on: September 28, 2014, 09:24:06 pm
Hi, I have supplied some links to indicate the complexity of getting a stable and accurate gas analyser.
The SUN unit uses a SIEMENS IR gas bench, and when I was servicing ALLEN benches I was told that they were originally designed for blood and fluid analysis.
Lambda is a calculated value, not measured directly from the gas.

Hope this helps.

Tom...... smiley
Thanks, Tom.  Wow! That Lambda formula is mighty complicated.
12  Using Arduino / General Electronics / Re: Help with small electronics project on: September 28, 2014, 08:57:48 pm
Exactly.  The other point being, even if you fuse it at 1/10 Amps, if you supply 25V to the Arduino RAW pin, the Regulator on the Arduino will BLOW in less than a microsecond.  Then, milliseconds later the fuse will blow.  If you're lucky, the Regulator will fail in the shorted mode thereby sending the 25V to the rest of the board.
That kind of luck I don't need.  smiley
13  Using Arduino / General Electronics / Re: motor and L293DNE problems on: September 28, 2014, 08:45:42 pm
i have a l293dne & i have connected it to my microcontroller as shown:
 battery  is 18v (two 9v battery in series) also tried using 9v .The voltage produced across the pins (3 & 6 for right wheel motor & 11, 14  for left wheel motor  as per above image) is perfect i.e around 9v is produced the motor i am using is as here:
they can operate from 9v-12v.
the pins of l293dne produce exactly  18v but, these motors do not rotate.
But when i separately connect battery with motor it runs.
when i connected  a led it litted up even when i connected a motor of 3-5v it also worked properly.
But these  motors(as in image) are not running what may b the reason?
If you're using PP3 9V batteries, (the rectangular ones) they probably can't supply enough current to turn your motors.  Try with a mains adaptor [wall wart] or a lead/acid (12V car) battery to see if that works.
14  Using Arduino / Programming Questions / Re: Check if there´s an number after the comma on: September 28, 2014, 07:56:47 pm
How can I make the Arduino check if there´s an number after the comma?

(if it´s 3.25434, not just 3)

So, if it´s a natural number without digits after the comma...

That is a decimal place / period / full stop. Not a comma.
In some parts of Europe, a comma is used as the decimal separator.
15  Using Arduino / Project Guidance / Re: Pin Outputs In Parallel/Disabling Pins? on: September 28, 2014, 07:23:16 pm
If you are driving your LEDs in "sink" mode, you can connect the cathode of the diodes to each Arduino.  Connect the anodes together and to the C/L resistor for the LED.

If you are driving them in "source" mode, connect the anode of each diode to the Arduino and the cathode to the C/L resistor.

Before there were OR gates, an OR gate was built using diodes or transistors.
To be exact, before there were TTL logic ICs there were DTL logic ICs. Before there were DTL logic ICs there were DDL logic ICs. Before there were DDL logic ICs the logic was built out of separate components.
Appears Henry_Best has the same idea.  We both posted at the same time.
Great minds think alike  smiley
And, as I pointed out, using diodes will protect the pins on both Arduinos, whatever states they are in.
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