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Some types of electronic equipment do  not provide any indication that they are  actually on when they are switched on.  This situation can occur when the back-light of a display is switched off. In addition, the otherwise mandatory mains  power  indicator  is  not  required  with  equipment  that  consumes  less  than  10 watts. As a result, you can easily forget  to switch off such equipment. If you want  to know whether equipment is still drawing power from the mains, or if you want  to have an indication that the equipment  is switched on without having to modify the equipment, this circuit provides a solution. One way to detect AC power current and  generate a reasonably constant voltage  independent of the load is to connect a  string of diodes wired in reverse parallel in series with one of the AC supply  leads. Here we selected diodes rated  at 6 A that can handle a non-repetitive  peak current of 200 A. The peak current  rating is important in connection with  switch-on  curr...

This is a simple solar charger circuit project can be designed using few external electronic parts . This simple solar charger circuit is capable of handling charge currents of up to 1A. Alternate component values are given in the figure for lower current applications. The only adjustment is the voltage trip point when the current is shunted through the transistor and load resistor. This should be set with a fully charged battery. As the transistor and R3 have the entire panel’s output across them when the battery is fully charged, all of the current from the panel will be going through R3 and the Darlington transistor TIP112, so these must be well heat sunk. Adjust R1 for the trip point, usually 14.4 V – 15 V for a 12 V SLA or a 12 V Ni-Cd battery.

Circuit Diagram Description Here’s a circuit to display the song number in an audio system for quick reference to songs. It also serves the purpose of an extra visual indicator in modern audio systems.When the power is switched on, the power-on-reset circuit comprising 3.3k resistor R20 and 1µF, 25V capacitor C6 resets the counters, showing ‘00’ in the display. One can also reset the display to zero at any time by pressing reset switch S1. When the first song starts playing, the output pins of IC1 (KA2281) go low and capacitor C5 starts charging. This forward biases transistor T1 and hence the input to IC3 at pin 1 goes to high state. As a result, the output of the counter goes to the next state, showing 01 on the display. The counter remains in this state until the song is completed.During the time gap before the next song starts playing, capacitor C5 discharges. After discharging of capacitor C5, the input to IC3 becomes low again. When the song starts, the process described above is...

This mousetrap is built around a PlC12F683 and uses an infrared transmissive optical sensor that is modulated at a frequency of 38 kHz, so that it isn't affected by the ambient light. The modulation is carried out by the PlC, which generates a 38 kHz signal at port GP2, which is connected to the lR LED. The lR receiver is a type that is usually found for use with remote controls. lt reacts only to 38 kHz signals. lt reports the presence of an lR signal to the PIC via port GP1. When the lR lightbeam is broken the PIC turns of the relay via port GP4 and FET T1 , which: causes the door of the mousetrap to close. The transmissive optical sensor is housed inside a small wooden box. A small amount of food is placed inside this box. Animal Friendiy Mousetrap Circuit diagram : Animal Friendiy Mousetrap Circuit Diagram When a mouse walks through the light beam on its way to the food it causes the door to shut behind it and an LED starts flashing. The door is normally kept open by the coil ...

Programmer and Development Board from Extremeelectronics: Look at the below picture. The programmer I am using is bought from another manufacturer, not from extremeelectronics. It is an USB Porgrammer. You can get it from any leading electronics hobby electronics store. My programmer is not pin compatible with XboardMini which I brought from extremeelectronics. I modified the ISP connector for connecting the USB programmer with the board. The XboardMini does not has Vcc connection in its ISP connector. My programmer has Vcc connection in its ISP connection. 10th pin is free (not connected) in the Xboardmini ISP circuit. I modified my cable such that 9th pin gets Vcc from USB programmer. The red wire I connected goes from 10th pin to one of its Vcc node. In this way, the board directly gets Vcc from USB power supply. You dont have to use 9V adaptor for programming and powering the board. I dont know whether the usb programmer from extremeelectronics is having Vcc connection in its ISP P...

it’s an Arduino-compatible microcontroller board for interfacing with radio frequency (RF) modules, such as the popular 433/315MHz transmitter/receiver, and the nRF24L01 transceiver. The RFToy has a built-in ATmega328, USB-serial converter (CH340G), 128×64 OLED display, three buttons, and a coin battery holder. Programming is done in Arduino through the on-board mini-USB port. It has three sets of pin headers to directly fit RF modules, and an audio jack to output RF receiver signals to a computer’s sound card. Using RFToy you can build a variety of projects involving RF modules, such as remote control and wireless sensors. [ ]

This is a simple project of 2-Wire Temperature Sensor Circuit Diagram. The Type LM35 temperature sensor from National Semiconductor is very popular for two reasons: it produces an output voltage that is directly proportional to the measured temperature in degrees Celsius, and it enables temperatures below zero to be measured. A drawback of the device is, however, that in its standard application circuit it needs to be connected to the actual measuring circuit via a three-wire link. This drawback is neatly negated by the present circuit. When the LM35 is connected as shown, a two-wire link for the measurement range of –5 °C to +40 °C becomes possible. 2-Wire Temperature Sensor Circuit Diagram:     Two-Wire Temperature Sensor Circuit Diagram Actually, the circuit shown is a temperature-dependent current source, since it uses the variation of the quiescent current with changes in temperature. The values of resistors R3 and R4 are calculated to give an output voltage of 10mV °C–1....