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Let an MCU Feed Your Pets - 13-May-10 -Design News: Pet owners who want to spend a day hiking, at the beach, shopping at the mall or even a weekend far from home can build an automatic pet feeder to dispense water and dry food at a preset time. Tom Thompson, Julie Redmond, Curtis Siebenaller and Nathan Woodworth at Colorado State University explain __ Gadget Freak-Case #164
Letterbox Monitoring systE - M - If your letterbox is some distance from your house, you will find a monitoring device useful to indicate when new post has arrived. This can take the form of a US-style visible flag; a more modern alternative uses a 433 MHz radio transceiver. The big advantage of the solution presented here is that is can use an existing two-core bell cable, without requiring any further power source. The arrival of post is signalled by a blinking LED; for added effect, a digital voice recorder can also be connected which will, at regular intervals, announce the fact that the letterbox needs emptying. The device is silenced by a reset button. __ Designed by Robert Edlinger© Elektor Electronics Magazine
Letterbox with Letter-Counting Facility - Here is a circuit that starts counting when you insert a letter in the letterbox at your home or office. It is designed to save your time from going to the...__ Electronics Projects for You
LF LowFER Beacon Transmitter - Here's a complete LF Beacon transmitter for LowFER (Low-Frequency Experimental Radio) . The transmitter is designed for license-free operation between 160 kHz and 190 kHz, consuming the legal limit of 1 watt power input to the final RF output stage. For fun, the complete transmitter is built into an Altoids mint tin. The circuit is built dead-bug style on a piece of copper clad circuit borad material, lightly painted with Testors transparent Hot Rod Red to prevent tarnish. The paint doesn't seem to make soldering any more difficult. The board is grounded to the tin in a few places. __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Light Collar Helps You Find Your Pet In the Dark - 10/07/10 EDN-Design Ideas Keep your pet from getting lost in the dark. If you have a pet, you know how difficult it is to find him or her in the dark, especially when your pet has dark fur. The circuit in Figure 1 lets you build a collar with LEDs that helps you find your pet. The heart of the circuit is the ZXLD381FHTA LED driver from Zetex. Two 1.2 or 1.5V cells power the LED driver, providing the current pulses to illuminate six to eight 20-mA LEDs of any color series. The ZXLD381 dc/dc boost converter’s primary application is in LED drivers. Design by Vladimir Oleynik, Moscow, Russia
Light Fence - The basic problem with most of standard light sensors is that they require precise alignment of light beam to mute the circuit during standby mode. The circuit described here is so...__ Electronics Projects for You
Light-Equipped Drone Is Your Personal Lighting Crew - 4-Aug-14 -Design News: Cabe AtwellManohar Srikanth, Kavita Bala, and Fredo Durand have innovated a drone that dynamically lights moving subjects with a designated rim lighting effect at the photographer's discretion. While these drones are still in the prototype stage, they are a testament to what can be done with drones in photo __ Gadget Freak
Lightning Detector - Egor! Come quick! A storm approaches! Here is a VLF receiver tuned to 300 kHz designed to detect the crackle of approaching lightning. A bright lamp flashes in sychrony with the lightning bolts indicating the proximity and intensity of the storm. Figure 1 shows the simple receiver which consists of a tuned amplifier driving a modified flasher circuit. __ Designed by Kyriakos Kontakos
Lightning Lights - Schematic + Info + pictures10 LEDs light up from top to bottom, following the lightning bolt’s path. The LEDs turn off back up into the cloud. The display looks best with backlighting. The bolt seems to glow in the dark. __ Designed by Lennie Zink
Linux Server Serves Cats - 8-Oct-07 -Design News: Lee Holmes' two cats get their portions served personally by his server computer. The computer stands right next to his homemade mechanical dry cat food dispenser, running the Subversion Version Control System under Ubuntu Linux. But at feeding time, it moonlights as a waiter. Activating the CD ROM __ Gadget Freak-Case #109
Litter Box - PIC Project Not every new use of technology requires a microcontroller. This one uses a 12 volt computer fan from CompUSA, a snap close food box from Walmart, some PVC pipe from Home Depot, and a large plastic storage container from Big Lots. __ Designed by Luhan Monat-Mesa Arizona
Little Door Guard - If some intruder tries to open the door of your house, this circuit sounds an alarm to alert you against the attempted intrusion. The circuit (Fig.1) uses readily available, low-cost components....__ Electronics Projects for You
Locksmiths Both Feared and Admired Elmer - 16-Aug-04 -Design News: After locking the door and leaving the keys inside one too many times, Elmer hit upon an entry strategy that involves no keys or codes to remember. He simply attached a timer to his door-bell, and a timer relay to the key switch terminals on the opener for the door on his attached garage. __ Gadget Freak
Low cost PCO billing meter - This is a circuit for a low cost PCO billing meter that counts the number of pulses during a certain call and displays the corresponding number of rupees charged on a calculator according to a pre defined pulse rate by user. __ Electronics Projects for You
Low-Cost Stopwatch - Here is a simple circuit of a stopwatch that can count up to 99 seconds. The circuit uses CD4060, CD4013, CD4033, LTS543 and some discrete components. A crystal-controlled oscillator generates 1Hz...__ Electronics Projects for You
Low-Sensitivity Sallen-Key Filter Design with the HP-41C/CV/CX Programmable Calculator - Programmable Calculator Software
Low-Sensitivity Sallen-Key Filter Design with the HP-67 Programmable Calculator - Programmable Calculator Software
Luckily Dimitri Never Inhaled - 4-Apr-05 -Design News: Preferring his tennis games to be of the table-top variety, Dimitri didn't like to repeatedly bend down and pick up balls. It slowed down his play and created wear-and-tear on his back. So he built a microcontroller-based, automatic ball dispenser. A player simply pushes a switch on the four-ball __ Gadget Freak |
