I'm using the RFID ID-20 Reader and the a 125kHz RFID tag (http://www.trossenrobotics.com/store/p/3620-Blue-Key-Fob.aspx) and I can't seem to read anything without tapping the tag against the reader. It is very important to my project that I get as much range out of this as possible, so can someone help me out.

I'm using the set-up below without the LEDs or speaker:

http://blog.workingsi.com/2010/10/arduino-rfid-tag-reader-cleaned-up.html

So that would work after all?

Alright, thank you for your help.

The first aforementioned shift register is connected to the Arduino by a clock, data, and latch pin. All the latch and clock pins are connected together. The data is sent from Ser out to Ser in on the next shift register. The shift register is connected to Arduino's 5V at its Vcc and SRCLR and the SRCK, G and GND are connected to ground. The segments are connected to Drain#'s with a resistor between. (Resistors are based on old power supply)

I've gotten it to work with a different power supply, but I'm trying to get it to work with this power supply.

The last power supply was just 5 AA's. I'm currently trying to get it to work with a wall plug-in power supply that gives 12V 2 A DC.

This shift register:
http://www.sparkfun.com/products/734

The Arduino supplies the 5V to each of the registers and sends out the bits and those are passed through each shift register by Ser out-ser in.

The shift register is already all figured out, I just need to figure out how to power the digits.

That's what I thought, but that's what the other posts seem to be saying if the resistors are only for each segment.

This shift register:
http://www.sparkfun.com/products/734

The Arduino supplies the 5V to each of the registers and sends out the bits and those are passed through each shift register by Ser out-ser in.

So the 12V goes directly into pins 1 an 5?

Alright I have a 12V, 2 A power supply and I need to power an Arduino Mega and 4 digits of a 7 segment display:
http://www.us.kingbright.com/images/catalog/SPEC/SA18-11EWA.pdf
that take 6V. (They're controlled with shift registers by the Arduino.)

If this the correct method then:
Oh I meant to ask about the resistor too. In Figure 22 there is a value of 3 OHM underneath the resistor, but there is a calculation involving R1 = ... to the side. Do I need to calculate the value of this resistor or is it 3 Ohms?


http://www.farnell.com/datasheets/76220.pdf

Well I found a 50V radial, so that should be fine, right?

So is the voltage rating of the capacitor important in this case? What does it mean? Is that the max voltage it's rated for or does it actually build up that difference?

So figure 22 here:
http://www.farnell.com/datasheets/76220.pdf
With this transistor:
http://www.newark.com/jsp/search/productdetail.jsp?SKU=25M7729&CMP=AFC-GB100000001
?

Thank you for your help!

Well it's an Arduino Mega, with about 28 pins filled. I don't pretend to know as much as anyone else here. That's why I'm asking the questions. I found the datasheet that showed the capacitors. It wasn't with the first link I found.

I just have a few questions:
It didn't seem like I could wire the voltage regulators in parallel, but is there anything I could do that doesn't involve finding another voltage regulator since the current one can only handle 1 A? Will it draw more current than it can handle?

Will any of the components fry from too much current or will they only draw what they need?

 

You're right. Good catch. What's the difference? What would you use the other one for?

I really need the last post I did answered though.

How do i know what capacitors to use? In series, right? The regulators themselves don't take any current, right? I was thinking that I'd have the 12+V go directly to the Arduino then through the parallel capacitors and regulators and then to the digits? I thought the digits would take 540 mA at max with all 8's and then the Arduino could have at least 1,460 mA.

So I can just send the 12V directly to the Arduino and then can I put two 6V regulators in parallel somehow for the digits? Would I need to? The regulator I found says it can only handle 1 A I believe:
http://www.opentip.com/Electronics-Computers/Voltage-Regulator-To-p-1261539.html

So just sending 12 V into a 6 V regulator will bring it down to 6 V? Will each component only draw as much current as it needs?