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1  Using Arduino / General Electronics / Re: Basic question: Arduino wires on: April 18, 2014, 04:05:07 pm
I think unobtanium is often used in electro-magnetic systems
2  Using Arduino / General Electronics / Re: can I use duct tape on this project? on: April 18, 2014, 02:33:39 am
Mike, if you've never used the aluminium type you don't know what you're missing.  Aluminium foil (no fabric) with an adhesive backing, extremely thin.  It's wonderful stuff for sealing all sorts of gaps.  It moulds in well and sticks like **** on a blanket, and it's relatively heatproof.
http://www.tlc-direct.co.uk/Products/TLAT50.html?source=msn&kw=16327816894
3  Using Arduino / General Electronics / Re: what resister values to use with a transister NOT gate? on: April 17, 2014, 03:51:40 pm
You need a collector resistor to control the current through the transistor.  Do not run it at 100% (20ma) so suggest you use a 1k in the collector circuit.  The second resistor is to control base current.  I suggest you use a 10k in that location.  This should feed enough base current to ensure full saturation of the transistor (ie turn it fully on).
4  Using Arduino / Motors, Mechanics, and Power / Re: It's faster a motor or a solenoid? on: April 16, 2014, 03:52:17 pm
A loudspeaker is effectively an "inside out"  solenoid and can oscillate at around 20kHz
A DC electric motor can run in excess of 20,000RPM
They can both do 20,000 "somethings" but there ends any comparison.
One is linear motion and the other is rotary motion, so what exactly does your question relate to.
5  Using Arduino / General Electronics / Re: valley peak detector on: April 15, 2014, 01:37:01 pm
A zener diode won't do as it'll fail to conduct until the zener point is reached.  You can use any old diode providing you rig it up as a "precision rectifier".  see the following circuit  http://en.wikipedia.org/wiki/Precision_rectifier  which also shows it used as a peak detector, further down the page.
6  Using Arduino / General Electronics / Re: valley peak detector on: April 15, 2014, 02:31:40 am
What do you mean by "valleys"  Do you mean the maximum negative peak or the lowest voltage that the "rectified" signal fall to.
7  Using Arduino / Motors, Mechanics, and Power / Re: Failed to drive a CD Rom sled motor via Hall effect sensor. on: April 14, 2014, 12:24:23 pm
and then rotate it because it's also back to front
8  Using Arduino / General Electronics / Re: snubber circuit capacitor and resistor? on: April 14, 2014, 07:27:27 am
Hopefully this document tells you the technical story behind the snubber requirement / design

http://www.soloelectronica.net/triac/AN_3003.PDF
9  Using Arduino / General Electronics / Re: How can I find out why a small DC motor won't work? on: April 07, 2014, 02:47:46 am
If you simply wired the speaker to the car horn circuit then you will indeed have destroyed it. 
A car horn circuit is a simple 12V DC system which is either ON or OFF. 
A speaker operates from an AC signal source (amplifier) matched to the speaker impedance, usually 4, 8 or 16 ohms. 
If wired directly to DC, all that will happen is the cone will give a single click as it moves to a new fixed position and excess current will flow through the voice coil windings.
10  Using Arduino / General Electronics / Re: How can I find out why a small DC motor won't work? on: April 06, 2014, 06:25:31 am
Cut one of the motor leads to isolate the motor from the rest of the circuit, then apply voltage, 6 or so, to the motor terminals to see if it will run.  This will verify if the motor is defective or the motor drive circuit is defective.   Note that if the motor is defective its drive circuit might also be defective.
11  Using Arduino / General Electronics / Re: Take pictures with DRAM!!! on: April 05, 2014, 12:59:39 pm
and here's me thinking it involved taking photographs whilst supping at a glass of the "water of life"
12  Using Arduino / General Electronics / Re: Where can I buy an Electro-Permanent Magnet? on: April 05, 2014, 12:56:54 pm
Many thanks for the educational bite - never too old to learn - though at my age retention of yesterday's education is a problem  smiley-grin
13  Using Arduino / General Electronics / Re: Where can I buy an Electro-Permanent Magnet? on: April 05, 2014, 11:08:47 am
What's an "electro-permanent magnet"
Electro magnet = one that is magnetic when energised
Permanent magnet = one that is permanently magnetised

So what is it you are looking for ?
14  Using Arduino / General Electronics / Re: I need help understanding my adjustable power supply on: April 05, 2014, 03:40:09 am
I agree Mike, I misread the OP's text
15  Using Arduino / General Electronics / Re: I need help understanding my adjustable power supply on: April 05, 2014, 02:05:45 am
The metering switch is merely a display selector.  The meter can only display one value at a time and the 4-way slider switch selects the value to be displayed.

The output voltage is determined, when in independent mode by the setting of the voltage adjustments.  the output current is determined by the load that you apply to the terminals and the voltage appearing there.

In tracking mode, voltage B follows what A is set to, depending on how you have set the 2-way mode switch.

The 1.45 volts is the drive voltage that the supply provides with NO load.  When under load the output is drooping down to 1.36 which means the regulation is somewhat poor.  Perfect regulation would maintain the set voltage irrespective of the current load.

You say you are charging 3 cells in series and only getting a battery voltage (batteries are a collection of cells) of 1.3V.   It appears that your cells are either defective or extremely depleted and will need in excess of 10 hours of charge to recover.

The green terminal is probably attached to the casing and is used, if desired to connect the casing to the circuit you are working on to maintain an earth reference.  In normal circuitry work you can completely ignore it.  You might care to test to see if it is connected to any of the output terminals  -  it shouldn't be!
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