Saturday, October 25, 2014

Hobby Diy Oscilloscope

Is it good as a (beginner) hobbyist to crave for an oscilloscope.  mail from EA

This scope will work from your PC Audio Card or Sound Card. You First need to build the circuit below and connect it to Line-in of Sound Card.

xoscope for Linux

xoscope is a digital oscilloscope using input from a sound card or EsounD and/or a ProbeScope/osziFOX and will soon support Bitscope hardware. Includes 8 signal displays, variable time scale, math, memory, measurements, and file save/load.

Hobby Diy Oscilloscope

Zelscope: Sound card oscilloscope and spectrum analyzer

Zelscope is a Windows software that converts your PC into a dual-trace storage oscilloscope and spectrum analyzer. It uses your computer's sound card as analog-to-digital converter, presenting a real-time waveform or spectrum of the signal.
Digital PC Oscilloscope
"Our group decided to pick the Personal Computer Oscilloscope because it sounded very interesting to approach. We also felt it would help us in understanding many aspects of hardware and software interfacing. We also wanted to do something that we felt was consumer electronic related to the current market and was interesting in working with."


Friday, October 24, 2014

Secure Entry Access Control - Smart Cards

I am working on an access system, multi-user code for entry to restricted areas. I designed one that uses purely hardware but its a bit complicated and bulky, though it works perfectly. Might you have any ideas on implementing microcontroller based systems. Any information would help me at this stage as i am still investigating my options.

Post by RT

These days smart card technologies are used for access system in most places. It uses a RF card the size of a Credit card with a microcontroller embedded in it. and you need a smart card reader that needs to be networked or interfaced with PC. philips, atmel, maxim, fujitsu and many more sources for kits, products and parts. many embedded 80C51 family type solutions were there when it all started.

Secure Entry Access Control - Smart Cards

Smart card, chip card, or integrated circuit card (ICC)

Contactless smart cards

A second card type is the contactless smart card, in which the card communicates with and is powered by the reader through RF induction technology (at data rates of 106–848 kbit/s). These cards require only proximity to an antenna to communicate. They are often used for quick or hands-free transactions such as paying for public transportation without removing the card from a wallet.

Like smart cards with contacts, contactless cards do not have an internal power source. Instead, they use an inductor to capture some of the incident radio-frequency interrogation signal, rectify it, and use it to power the card's electronics.

Study Resources Below

Smart Card Technology and Security 

A Smart Card and a Card Accepting Device (CAD) communicate via means of small data packets called APDUs (Application Protocol Data Units).

Useful Things for Smart Card Users 

Modules for Smart Card Microcontroller, Examples for application level Communication, Connection of a Smart Card to a Microcontroller, Instructions for Smart Card current measurement.
Other Notes

When this post was first made 8 links to sites with info was added by me. Today 2012 most of the links are broken. So new sites are listed.


Tuesday, October 21, 2014

Graphic Equalizer Circuits

plz send me sound equalizer circuits. - email by AH
Search for ...... graphic equalizer circuits. You have many pages to see, and the navigation for all the pages is at bottom of every page. anyway, i did it for you,

Graphic Equalizer Circuits

10 Band Graphic Equalizer (sam)

"The circuit of graphic equalizer, allocates ten adjusting potesometer , that each one from them affects in a predetermined area of frequencies, the central frequency of which abstains a octave (double), from the central frequencies of her neighbouring regions."

3 Band graphic equalizer (andy)

This circuit is similar to ones that used to come in Philips audio books, so try this first. Now to design your own, learn the technique here ...

"Using a single op-amp this easy to make equalizer offers three ranges, low frequency,mid frequency,and high."

7 band Audio Graphic Equaliser

"The details shown are for a 7 band but the principle can be extended to almost any number of bands - if you can find accurate enough components."

Level, Tone and Balance Controls

Amplifiers, tone controls and other audio effect circuits at david's "Discover Circuits".