Designing an RFID antenna - part 1

Designing an RFID antenna:

Basically I am motivated to replace the antenna on this RFID reader. The reader is really cheap, and fits my porpoise, its recognized as a USB keyboard.

My Idea is to build a new antenna that can be fitted into a PVC tube and have a usb "reading rod".

Hackaday has provided me with some information about this, but nothing useful about antenna modding.

Thanks a friend (Chris) I manage to get some technical documents (such as this,  this, this) about this matter, some turned to be really useful and cover basic subject (like Magnetism, Faraday's Law, Mutual induction) it really help me understand more about RFID, it sure brought me memories when I was in college, but could not find any decisive information on how to shape a new antenna.

I know antenna shapes and geometry are dependent on: Frequency (125 Khz in this case) and range of reading (of the tags) and number of turns. Of course many other items, but they are purely derivative from the two I mentioned first.

So I disassembled my rfid reader:

Up to here all done, simple building, now I will desolder the coil antenna, saving it in case of reusing it or take it as a model.

Desoldering was easy, two points, done! You can see below the antenna saved for future.

Now the best part, with 20 meters of copper wire I am planning to do some coils, in order to check which confirations works best.

 

Three basic squares using push pins, will serve two make the coils and test them.

I have 3 configurations to test:

a)50mm x 60mm

b)40mm x 50mm

c)35mm x 120mm

Tune in for future results!

Satellite Gear Modding:Adding fans to AZAmerica s900 sat reciever + Ibox

The both of them run really hot, hands into matter, ordered two flat vga fans from aliexpress (THIS).

Az America s900:

Disconnect all equipment from AC !!!!!

Take out the cover, and disconnect the power source, and all other cable attached to work comfortably. Here we go!

 Once opened just locate some pins that can provide some acceptable voltage. See next picture, I found a 5v and ground. (5v will garantee a smooth operation)

 I simply pinched into the cables, before the entered the next connector, and tested. After that, I just simply attached up from the heat sink.

Always test, check, and then re fit all back togheter.

IBOX:

Disconnect all equipment from AC !!!!!

Simple 4 screw on the back of the box. 

Disassemble and you get this, there's the tiny heat sink.

The power jack is ideal, since ibox runs on 12v (check you power source), look at the back of the board, and use one of the holes to pass the cables to the back.

Once tested with which pins does it work, solder and test. Just to keep it on the safe side, you can add some glue-gun in order to isolate.

Once in position, see that the blades does not hit any component on the top board. I used some screws to attached the fan into the top cover.

Put the box together, and ready to go, if the fan is too noisy you can add a 10k potentiometer or a resistance.

Anti Rain flood system - Arduino water pump Automation

Been having some trouble at home due to a poorly designed water drain, heavy rains just put at risk overflowing with the drains capacity, I got some problems after getting some water inside my house so I took matters into my own.

The idea is to have and automated system to drain the water out of the "warning zone" out to another place, another idea is to harvest this water if you have the place to store some big containers.

Target: have a fully automated system that can measure the water level and in case the level is near the "warning" level, it activates a water pump to lower the level. As a secondary target the idea is to see the level in real time through a web page.

Bill Of Materials:

Item	Pictures
Arduino (using UNO, will port to pro mini)
Network shield ENC28j60
Distance measuring module HC-SR04
5v relay module
Old wireless repeater DLINK
Water pump 1/2 horsepower
Enclosing box
Power cord & extension
Hose & quick connectors connector
Pvc tube
Ping pong ball
General materials: glue, soldering iron, electrical tools

Here are basic schematics for this project:

Tube assembly:

Block Diagram:

Phases for this project:

Phase 1: get the basic software working. Code the basics for the arduino to measure the distance and upon threshold, activate relay.

Phase 2: building the container for outdoors. Using an hermetic plastic container (a big tupperware :) ), fit all the parts in there, water proofing it, build the pvc tube with the sensor container.

Phase 3: initial testing, a data analysis.

Phase 4: attach wireless repeater in client mode, using network module to: monitor system from web, upload measurements information to mysql database.

Stay tuned for how the project evolves.

New toys! Lets gets started!

New toys arrived

Last shipment arrived to I can finish an automated pump system, measuring water level with a HC-sr04 sensor module. Some other goodies also arrived to make projects work more tidy.

Embedding an RFID tag into a phone: not so simple

Embedding an RFID tag into a phone: not so simple

Inspired by this site I decided to have one of my rfid tag embedded into my iphone 4s, as to use is a master key on my future developments.

I started dissolving the tag with acetone, and while dissolving I started to read some documents on RFID antennas (link) great document, covers from the basics!

Let me tell you a couple of things about embeding

1) I dissolved 2 tags.... first one, stopped working.

2) The one I dissolved does not fit, and cant tear it apart. So, I'm not so happy, though this was going to be easy.

Working dissolved tag:

Not working tag:

Will keep update on the progress or abandonment of this project (quoting Murphy: If at first you don't succeed destroy all evidence that you ever tried. )

Last goodies arrivedfrom china

Dx sure takes time in delivering nice Arduino and DIY toys in my country, but at last!!!!

Active Buzzer (DC 5V): simple great, to add some noise to our gadgets. Link

RF ID Proximity Token Tag Key Keyfobs Keychain - Blue + Silver (10 PCS): I've always wanted to start to explore on RFID, this is a great simple, cheap starting point. Link




Intelligent ID Card USB Reader: The crown jewel. =) Link This is a really cool item, this works as an input like a keyboard when it detects an RFID tag. 



This is my plan in mind, I was looking at this site. I wanted to start experimenting with replacing the antenna for a different one that could fit into a 1meter/5cm diameter PVC tube.

Stay tuned =)

Photosensitive Sensor Module Testing

I got this from DX: MN-EB-PTCMN Photosensitive Sensor Module - Orange.


Basically a photocell, after some investigation I got some help from this site, the code showed here is

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int photoRPin = 0; int minLight; int maxLight; int lightLevel; int adjustedLightLevel; void setup() { Serial.begin(9600); //Setup the starting light level limits lightLevel=analogRead(photoRPin); minLight=lightLevel-20; maxLight=lightLevel; } void loop(){ //auto-adjust the minimum and maximum limits in real time lightLevel=analogRead(photoRPin); if(minLight>lightLevel){ minLight=lightLevel; } if(maxLight<lightLevel){ maxLight=lightLevel; } //Adjust the light level to produce a result between 0 and 100. adjustedLightLevel = map(lightLevel, minLight, maxLight, 0, 100); //Send the adjusted Light level result to Serial port (processing) Serial.println(adjustedLightLevel); //slow down the transmission for effective Serial communication. delay(50); }

This code is property of Scott please take a look at his site for more interesting posts.

Thanks to this excellent piece of code you get a reading from 0-100 of the light sensed. Cool to build on to another things.

Here's an image of the serial console of the reading.

Heres a basic of the circuit, basic 3 pins (ground, 5v, signal(this goes to analog 0 in arduino))