TREE

Description . This circuit can be used to test whether mains voltage is present or not without having electric contact with mains line. The CMOS IC CD4033 is the heart of this circuit. The CD4033 consists of a 5 stage decade Johnson counter and an output decoder for converting the Johnson code to a 7 segment decoded output for driving 7 segment LED display . A 10cm long insulated copper wire connected to the clock pin (pin1) of the IC serves as the sensor. The sensor wire has to be placed in the vicinity of the mains wire to be tested. When there is no voltage in the mains line, no voltage will be induced in the sensor wire and the display will show a random digit. When there is voltage in the mains line, a small voltage will be induced in the sensor wire due to electromagnetic induction and this voltage is sufficient enough to clock the CMOS IC CD4033. Now the display will count from zero to nine and repeat. Circuit diagram. Notes. The circuit can be assembled on a Vero board. U...

This project was used as a wireless light dimmer, but in principle can be used to dim resistive loads and wirelessly turn on/off loads. The current code includes a routine to dim a light bulb in a “heartbeat” pattern, with the heartbeat frequency remotely adjustable. The top left of the schematic shows the wall outlet (US 120VAC) being stepped down with a small transformer, then full rectified and regulated. This powers the entire board from the wall. The top right shows a microcontroller, ATmega48, its programming header, and a UART connection to the microcontroller (for debugging). The bottom right shows the XBee and its basic voltage regulation (it’s 3.3V), as well as an LED that indicates when the XBee is connected. [ ]

Dorji Applied Technology from China builds different types of RF modules that can be easily incorporated in designing wireless data loggers, sensor network, telemetry and other wireless applications. Some of their RF modules have an additional pre-programmed microcontroller that allows direct interface of selected analog and digital sensors to the module. This means you don’t need any external MCU or to write codes for these sensors. In this tutorial, Raj from Embedded Lab talks about their DRF5150S and DRF4432S RF modules which are very versatile and easy to use for wireless sensor applications. For illustrative purpose, Raj shows how to put them together to construct a simple wireless sensor application where data from a remote sensor are received and displayed on a PC, without using any external microcontrollers. [ ]

Here is a low-cost and simple wireless stepper motor controller using infrared signals. Using this circuit you can control the stepper motor from a distance of up to four meters. The circuit comprises transmitter and receiver sections. The communication between the transmitter and receiver sections is achieved through infrared signals. Wireless Stepper Motor Controllers Circuit Diagram In the transmitter section, timer NE555 ICs (IC1 and IC2) are configured as astable multivibrators with frequencies of around 1 Hz and 38 kHz, respectively. The output of IC1 is given to reset pin 4 of IC2, so the 38kHz carrier signal is modulated by 1Hz modulating signal. The modulated signal from pin 3 of IC2 is transmitted by the infrared LED.  Resistor R5 limits the current through the IR LED. The transmitted signal is sensed by IR receiver module TSOP1738 (IC6) of the receiver section and its output at pin 3 is used as clocks for dual flip-flop 74LS74 Ics (IC3 and IC4), which are configured as a...

Walkie-talkies (also known as handheld or PMR, Personal Mobile Radio) can be bought at low prices even from department stores, and they can be operated without a licence in many countries. Considering the low cost, such a set would be very suitable for use as a wireless baby monitor, with the addition of several external components. These are connected to the jack sockets for an external loudspeaker/microphone and an external PTT (Push-To-Talk) switch, which are often found on these devices. Project Image : Wireless Baby Monitor Project Image The walkie-talkie with the extra electronics and microphone is placed in the baby’s room. When the PTT switch on the other walkie-talkie is actuated for about a second the ‘baby’ walkie-talkie produces a series of tones, which the external electronics can detect. This then activates its own PTT switch for about 5 seconds, so it switches over to transmit. During this time the other device can hear what the external microphone picks up. C...

Dorji Applied Technology from China builds different types of RF modules that can be easily incorporated in designing wireless data loggers, sensor network, telemetry and other wireless applications. Some of their RF modules have an additional pre-programmed microcontroller that allows direct interface of selected analog and digital sensors to the module. This means you don’t need any external MCU or to write codes for these sensors. In this tutorial, Raj from Embedded Lab talks about their DRF5150S and DRF4432S RF modules which are very versatile and easy to use for wireless sensor applications. For illustrative purpose, Raj shows how to put them together to construct a simple wireless sensor application where data from a remote sensor are received and displayed on a PC, without using any external microcontrollers. [ ]