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46  Using Arduino / Programming Questions / Re: Relay -why it acts the other way - help needed! on: April 17, 2014, 12:20:46 am
One application for NC is in a power fail circuit.
If your relay is powered by AC mains the NC contact will be open.
You connect a battery to the contact then to a bell.
When your AC mains fails the relay drops and the NC contact closes.
Therefore the battery is connected to the bell and the power fail is annunciated.
47  Using Arduino / Project Guidance / Re: Driving a 150 ohm speaker on: April 17, 2014, 12:08:42 am
Quote
I'm going to have to find a castle
You do teach fencing, when you get your picture taken make sure you wear chain mail.
You have the beard smiley-wink
I know you use a foil not a sword.
48  Using Arduino / Programming Questions / Re: HELP on PWM programmed on: April 16, 2014, 11:23:33 am
See image attached:
Do you want to limit the LEDs to on/off or is it OK to use PWM?

Edit:
In the final design, MOS fets would be more efficient than bipolar transistors.
49  Using Arduino / Programming Questions / Re: HELP on PWM programmed on: April 16, 2014, 10:23:23 am
What are LEDs you are you using, link please?
50  Using Arduino / General Electronics / Re: Need a battery source on: April 15, 2014, 10:50:01 pm
I have soldered similar, but others may suggest spot welding. 
Some battery stores might spot them for you.

3 days for delivery, WOW!
51  Using Arduino / Programming Questions / Re: HELP on PWM programmed on: April 15, 2014, 10:44:00 pm
How are you going to power the LEDs?
Where is the schematic from?
52  Using Arduino / General Electronics / Re: Inverse multiplexer? on: April 15, 2014, 05:45:00 pm
Try:
http://playground.arduino.cc/learning/4051
53  Using Arduino / General Electronics / Re: OP AMP 30v Supply on: April 15, 2014, 02:53:10 pm
See
http://forum.arduino.cc/index.php?topic=158242.0
54  Using Arduino / General Electronics / Re: OP AMP 30v Supply on: April 15, 2014, 02:48:55 pm
Use 3, 9volt batteries a NPN transistor driven by the Arduino.

55  Using Arduino / Motors, Mechanics, and Power / Re: 2222a transistor as a switch on: April 14, 2014, 09:07:21 am
Your Arduino to 2N2222, base connection needs a resistor, try 220R.
Debounce the switch.
Add 100nF capacitors to the input and output of the 7805. (Near the regulators pins.)

Edit: add 1N4007 across the solenoid (cathode to +12V).
56  Using Arduino / Motors, Mechanics, and Power / Re: 2222a transistor as a switch on: April 14, 2014, 08:56:58 am
Always use a fly back diode on a DC coil relay/solonoid.
Show your code.
Schematic, YES!
What is the coil resistance?
57  Using Arduino / General Electronics / Re: Need a battery source on: April 12, 2014, 07:40:07 pm
Perhaps a battery for a cordless screw driver will work.
58  Using Arduino / General Electronics / Re: How Do I Solder DC Motors With Flimsy Copper Pieces To Wires? on: April 06, 2014, 09:02:44 pm
If you want repeatable success, whether there is flux in the core or not, use a flux pen or similar
59  Using Arduino / General Electronics / Re: LED Indicators for bike schematic on: April 05, 2014, 11:40:20 pm
I'm not visualizing it very we'll, draw a schematic what you propose.
If the Arduino cannot supply/source enough current then a transistor is always an option.
60  Using Arduino / Microcontrollers / Re: programming atmega328p-an with Usb 2 serial converter on: April 04, 2014, 11:36:56 pm
No, 22mfd, you need 22pf

Show us a image of the circuit.
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