This page is describes the construction of an RFID reader using only an Arduino (Nano 3. 0 was tested, but others may work), a hand-wound wire coil, and some assorted low cost common components. RFID readers are devices sold by companies such as Parallax to read RFID tags with embedded identification circuits (we focus here on passive tags, activat
Click here to download the full size of the above Circuit.
ed by the reader`s transmitted RF energy). The design presented here shows how to wind a simple wire loop by hand (or create an equivalent printed circuit spiral version), connect it to an Arduino (or its chip), add a few low cost common components and create your own RFID reader. To make it more interesting (i. e. challenging), we will focus on the FSK class of RFID tags, which are fairly common among the 125kHz devices, but for some reason are not supported by the Parallax kits. Micah Dowty has shown a design for an FSK/ASK RFID reader built around a Parallax Propeller device. His code, which is in assembly language, implements an ingenious (but complex) algorithm to create a dynamically variable analog bias voltage, which is used to pull the weak RFID signal into range, so it can be discriminated into binary signals by the Propeller`s digital input circuitry. He also dynamically tweaks the transmit/receive RF frequency to keep the antenna`s tank circuit in peak resonance for optimal signal to noise. There are three problems with his approach: first, the passive detection circuit lacks amplification, which makes it very sensitive to noise and therefore raises reliability issues. Second, the design is based on the Propeller chip, and if you are a fan of the Arduino and/or associated Atmel AVR chips, it leaves you out. And third, the dynamic slewing of frequencies and bias voltage is overly complicated, making it hard to...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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