TREE

Varactor (or “varicap”) diodes are used primarily in radio-frequency (RF) circuits to provide a capacitance that can be varied by changing the applied voltage. These types of diodes often are used for tuning circuits, such as RF oscillators and filters found in wireless applications like wireless microphones and radios. Designers, then, should know about the benefits of using a nonvolatile digital-to-analog converter (DAC) to provide the biasing voltage of a varactor diode used as a voltage-controlled capacitor. The varactor diode is operated under reverse bias, which creates a depletion zone around the P-N junction. Changing the level of the reverse bias changes the thickness of the depletion region and, thus, the effective capacitance of the diode. Increasing voltage causes a decrease in capacitance. Varactor diodes are specified with a nominal capacitance value and the range of capacitance that can be achieved with a maximum and minimum voltage level. Increasing the bias voltage ran...

Many times the hobbyist desires to have a simple, dual power supply for a project. Existing power supplies may be large either in power output or physical size. a simple Dual Power Supply is necessary.For most non-critical applications the best & simplest choice for a voltage regulator is the 3-terminal type.The three terminals are input, ground & output. The 78xx & 79xx series can provide up to 1A load current & it have on chip circuitry to prevent damage in the event of over heating or excessive current. That is, the chip basically shuts down than blowing out. These regulators are cheap, simple to make use of, & they make it practical to design a method with plenty of P C Bs in which an unregulated supply is brought in & regulation is done locally on each circuit board. This Dual Power Supply project provides a dual power supply. With the appropriate choice of transformer & 3-terminal voltage regulator pairs you can basically build a tiny power supply deli...

We built a biometric fingerprint-controlled lock prototype. A fingerprint scanner is used to capture and store the fingerprints of authorized users. When the scanner recognizes a user, a solenoid plunger disengages and opens the lock. [ ]

After a full day of work and mind bubbling activities in the workplace, the last entry in a young professional’s diary is to go to a movie theater to relax. The sight and sound of a movie theater relaxes and easily entertains even the most stressed moviegoer. The problem with this however is the fact that even before you reach the movie theater, traffic jam may be a hindrance to your enjoyment. Traffic jam usually makes you more stressed than you currently are. It may be best if you can bring home the relaxation and entertainment. Having to sit and relax with your spouse in your own home theater maybe best to eradicate the tiredness that you feel. This is why the concept of home theater is born. Because of the growing popularity of home theater systems, you may easily find home theater furniture like home theater seating system and home theater equipments that will suit your requirements. This modern concept is slowly receiving a grand welcome from people because in the end, having hom...

I’ve owned a Iphone for a while now, it’s an amazing phone, the best I have ever used so far. But when I first started using it, my only concern was that the battery didn’t last as much as I expected. After two days, it was gone, and when I needed it, the phone just didn’t turn ON. I used to let the wireless on almost all the time and downloading many new apps. Now that I have some more experience on how my little gadget works, I will try to share some ideas on how you can optimize your iphone’s battery life and have a better iExperience. Wireless connectivity will drawn your battery even if you are not using it. Keeping it on, it will always try to connect to some open hot spot, try to check your emails and much more. So a good idea is to turn it on when using, and after, turn it off. Bluetooth have a similar battery usage as Wi-Fi, so there’s not much reason to leave it on if you are not using it (I believe that the most common usage for bluetooth today is the headsets and car kits)....