This article details an AC-based continuity tester designed for frontline test and repair jobs. The circuit provides a simple GO/NO-GO test for localizing faults in multicore cables. Open circuits are more likely at connector ends. By identifying the faulty end, the AC continuity tester allows you to open and repair the correct cable end. This action avoids the risk of damaging a good connector by opening it up. This approach is also useful for testing an installed cable with ends at different locations.
The schematic illustrates a circuit for a continuity tester that injects an AC signal on one cable wire and then looks for the absence of capacitive coupling on the other wires. One end of a bad cable typically shows good AC continuity, while the other end typically has one or more connector pins with no AC continuity. Because a short in the cable appears as a good connection, the operator can easily confirm that the tester is operating correctly by simply shorting its test leads together.
The left side of the circuit uses a low-power dual comparator (MAX9022) to form a relaxation oscillator operating at approximately 155kHz. It produces a peak-to-peak output signal approximately equal to the supply voltage, which is fed to a connector of the cable under test. The right side of the circuit processes any AC signal picked up by the inter-lead capacitance. That AC signal is first rectified by a pair of silicon diodes, and then integrated on storage capacitor C5. The bleed resistor (R5) provides some noise immunity and helps to reset the capacitor between tests.
The output resistor (R4) and input capacitor (C4) provide limited circuit protection. The circuit indicates OPEN for any test-cable capacitance below 100pF. (Thus, a standard 2m IEC mains test lead, whose typical lead-to-lead capacitance is 200pF, would test OK.) The circuit is also immune to false triggers caused by the 60Hz pickup from power lines.
Because the typical current draw of this low-power circuit is less than 40μA most of the time, the circuit can be powered by three AA or AAA 1.5V pencil batteries.
Many low-cost alternatives are available for the output device (e.g., a DC-activated piezoelectric buzzer), and most alternatives feature a suitably wide operating voltage range. The 100nF capacitors are standard ceramic decoupling capacitors, and the circuit contains no critical passive components. The comparator’s high-side drive is better than its low-side drive, so it should be used to source (rather than sink) current to the indicator device. Diodes D1 through D3 are silicon diodes.
AC Continuity Tester - [Link]
Jan_Henrik @ instructables.com writes:
in this Instructable I want to show you, how you can program your Arduino with your Android device. It is very simple and cheap. Also it allows us to program our Arduino where ever we want, this is usefull for permanently installed Arduino boards, like in light controllers…
Program your Arduino with an Android device - [Link]
Have no fear… even if this project sounds complex, you’ll easily learn in this article many things about high speed electronics and PCBs. In fact, my goal here is to teach you some basics about all the new problems that arise when you’re dealing with GHz signals
Amplifying nanosecond pulses for quantum physics experiments - [Link]
Summer offer of company Wago brings us a price-gainful set of favorite clamps together with a quality replica of official ball of incoming championship – Brazuca.
Opportunity to gain a souvenir of a great sport event usually lasts only some time. DVD, poster, mascot and other “gift items” are usually valued and required things. But perhaps the most precious is something, what we can use ourselves. In this case it is a quality replica of the ball Brazuca, which is as known an official ball of world football championship Brasil 2014.
How to gain it? All that is necessary is that you also need well-known and well-proven installation terminal blocks series 2273. At purchase of a special Wago set 887-119 you´ll gain 400 pcs 2273-203, 400 pcs 2273-205, high-quality replica of the ball Brazuca and a practical pump with a needle valve usable also for other balls.
For the price of 89 Eur you´ll gain 800 pcs of installation terminal blocks and a valuable present usable to keep yourself fit :).
Take use of a special offer to have your own “Brazuca” - [Link]
Scheme-It is an online schematic and diagramming tool that allows anyone to design and share electronic circuit diagrams. Walk through how to create your own diagrams with the electronic symbol library and how to export and share your drawings.
Scheme-It – Online schematic and diagramming tool - [Link]
praveen @ circuitstoday.com writes:
LCD modules form a very important part in many arduino based embedded system designs. So the knowledge on interfacing LCD to arduino is very essential in designing embedded systems. This article is about interfacing a 16×2 LCD to Arduino. JHD162A is the LCD module used here. JHD162A is a 16×2 LCD module based on the HD44780 driver from Hitachi. The JHD162A has 16 pins and can be operated in 4-bit mode or 8-bit mode. Here we are using the LCD module in 4-bit mode. First, I will show you how to display plain text messages on the LCD module using arduino and then few useful projects using LCD and arduino. Before going in to the details of the project, let’s have a look at the JHD162A LCD module.
Interfacing LCD to Arduino uno - [Link]
By Dario Borghino:
Researchers at the University of California, Riverside have developed a silicon anode that would allow us to charge lithium-ion batteries up to 16 times faster than is currently possible. The new design relies on a three-dimensional, cone-shaped cluster of carbon nanotubes that could also result in batteries that hold about 60 percent more charge while being 40 percent lighter.
New li-ion battery anode could charge electronics in minutes - [Link]
Make your own touchless control interface providing 3D coordinates and gestures, in the form of an Arduino shield.
3D-Pad is a touchless gesture control interface providing 3D coordinates and gesture recognition, with a 10cm depth perception.
3Dpad: touchless gesture controller Arduino shield - [Link]