About this Site:
Circuit Exchange International (CXI) is my personal, non-profit home page about radio, electronics and computing. First created back in March 1999 and intended for anyone with similar interests, whether hobbyist, engineer or professional. You may be wondering why the home page has been translated, when google can do this automatically. The reason is that when my site was first introduced, internet browsers were much less sophisticated than today, and automatic translations did not exist. I've decided keep the Intro pages for nostalgia.

New Web Site URL:
Circuit Exchange has been hosted on Zen Internet for the last 23 years. I have been very happy with Zen but for financial reasons have changed Internet Provider to 3 Home Broadband. This uses 4G LTE (mobile SIM card on a fixed router) and so far has worked extremely well. The old site will shortly be deleted, and the new site is now hosted by Mythic-Beasts. The new URL is:

Please update your bookmarks or simply press ctrl-D from a computer or use the bookmark tab if on a tablet or mobile device.
Currently there are 349 schematics divided into 11 categories. Also included are tutorials, design and simulation sections. If you ever try and type Circuit Exchange International, then you'll realise why I abbreviate it to CXI.
This site has been viewed from over 230 Countries in all 6 Continents. Although largely a single effort, I do welcome contributions to this site. This website is made entirely on Linux using Bluefish All graphics are produced with the Gimp.

Icons Used
Some pages contain icons, which are explained below. You can also click the update page to see a list of new or modified pages. The link symbol, represents an external link. If the normal cursor, changes to a hand, this indicates a clickable link, or other action such as zoom or scroll will take place. Some links are underlined, but others may not be, this rule also applies to any web page on the internet.

Icon for the Circuit Index
Article Index.
Analysis Section
Design section
Theory section
Circuit Exchange Gallery.
All flag icons are links to the contributors page.
The page contains a Fritzing breadboard layout.
Contains assembly code.
Contains hex code.
Document in Adobe format.
Link to the contributors page.

Circuit Exchange Newsletter
If you would like to be informed about new circuits and articles I run a newsletter hosted by Freelists.org Just click the link below, or fromCircuit Exchange Newsletter the index page and enter your email address. You will then receive email about site updates. After entering your email address, click send and you will get a confirmation message (Click here for sample). Click the link (highlighted in red) to confirm, after which a second email will arrive with the word subscribed (sample here). You may delete these two emails if you want. Any other emails on the newsletter will be about new circuits and articles.

Device Compatibility
Computers, Laptops and TV's
This site works fine on all computers, laptops and most tablets. Now, of course there are Smart TV's, cars, terminals, hand held devices and some of these have Internet capable browsers. All use different pixel resolutions and colour depths and creating a consistent look across all devices is difficult. As all of the schematics on this site are large, I recommend a minimum viewing resolution is 1024x768 pixels.
Mobile Phones
When I first created Circuit Exchange, there were no tablets and mobile phones, I only had to create content for PC's and laptops. All mobile phones have a limited pixel resolution of around 300 to 480 pixels horizontal. You can test your mobile phones viewport by click here. Although very convenient you will struggle to see detail in schematics. The simple solution is to rotate your phone horizontally (landscape view).

This site uses HTML5, CSS3 and jQuery. It should work on most internet browsers. Now whilst most internet browsers adhere to the rules governed by the W3C, some browsers do not, most notably Microsoft Internet Explorer. For years and years web designers have had to jump through hoops, because some detail does not render properly or some feature not supported. I'm no longer supporting early versions of Microsoft browser, but suggest you try an alternative browser such as Firefox, GoogleChrome, Brave Browser or Opera. All schematics use PNG format so should be viewable on all browsers.

This site is also Android friendly and will work with most tablets. I currently test with an Android Tablet, Samsung Smart TV at full HD 1980 x 1020 pixels. Some pages may be a little hard to see on smaller displays, so I recommend a minimum resolution of 1024x768 pixels.

My Email Address:
To combat spam the email address below is an image, not text. You need to enter the address directly, it is not a link.
For verification the image reads: hal eight zero zero zero b at yahoo dot com.

Contributions:
You are welcome to contribute circuits or articles. Diagrams are best preserved in either .png or .gif format, images in .jpg format. I can accept most document formats, but its probably best to send in either .doc or .odt Libre Office or (Open Office) format. I can accept schematics from LTspice, Eagle, Kicad or Ktechlab direct.

Contributors
The home page is translated into 10 languages and I am most grateful to the following people who have made this possible :-
Amanda Van Leeuwen, Ricardo Venegas, Sindhu Adi Wijaya, Paulo Roberto do Amaral, Maria Rosendahl, Marco Deferre, Fidel from Ukraine, and Hartmut Schneider. All contributors appear on my credits page link below. You can also see my viewers gallery and disclaimer. I am also very grateful to Ron J, whose work appears prominently in the Alarm Circuits. Ron has also kindly made his meticulous artwork available to use.

Because of extended contributions and support the people IDd below have full permission to use or reproduce any article, circuit or content from Circuit Exchange International:

Disclaimer:

Please Note:
1. This site may contain technical inaccuracies or other errors.
2. Please DO NOT copy from this site. If you would like to use circuits please email me.
3. Linking to this site is actively encouraged, but please create a working link back to Circuit Exchange International
5. You may link to this site or any page, but please make a reference to the original contributor.
6. Some sites have taken circuits from this site and claimed it as their own work. They are without honour.

Privacy Policy (Cookie Policy)
This site does not use cookies. The old site used a web counter to indicate page popularity. This used a cookie that most browsers blocked prevented it working properly. This new site has no counters, trackers or advertising. The first page uses a google search tool to search this sites contents. There is also a link to the free newsletter.

Frequently Asked Questions
i) Most components are labelled using the System International numbering system.
ii) Please don't ask for schematics for domestic electrical or electronic equipment, I don't have any.
iii) This site is non-commercial, I do not sell or buy, components or circuits on this site.
iv) The update page contains links to the newest pages on my site.
v) I regret that I cannot help with college/school/university/project work, but see links below.

Help on the Internet
Sorry but I cannot help with college or course work. However, before asking for help, try to solve your problem yourself or search on google. Remember that anyone who helps is a volunteer and gives their time freely, demanding that you need an answer by a specific date will not help your plea. If you are still stuck try the following forums:

Electrical Engineering Community This site has discussion forums and a great source of information.
Electronics Point
Electro-tech-online

About the Web Master
As with many hobbyists, my interest in electronics started with radio. Back in the 1970's and 80's the radio frequency spectrum was largely free from interference. There was no broadband and no switch mode power supplies at that time (which radiate much of the interference we hear today). Distant reception was possible on the worlds oldest radio band ( AM or medium wave). Audio was not processed as it is today and bands were much less crowded. Radio Luxembourg was a popular choice and it wasnt long before I started experimenting with simple radio circuits. Electronics, radio and computing are intrinsically linked and if you know a little about radio, then you will know a little about electronics. One year I got a 65 in 1 Electronic Lab for Christmas. These kits can still be bought on Ebay and are a great introduction to electronics. Working through the manual I learnt a lot more about electronics, and peaked my interest. Computing (in the UK) started about 1980 with the Sinclair ZX80, the first affordable computer that you could build yourself. It was great for its time, but now the ESP8266 and ESP32 have much more power and are internet capable. On the Workbench

As with most hobbies, electronics, radio and computing can be rewarding, and sometimes challenging. It is always good to hear from fellow hobbyists around the world. Some recommended books, "The Art of Electronics" by Harrowitz and Hill, and if you are interested in circuit simulation, "The Spice Book" by Andrei Vladimerescu is a great technical reference. These may be available in a library near you.

Currently "on my workbench", shown right I have a motor control and torque circuit, and a Raspberry Pi Analog Interface. These circuits will be published shortly.