Matt circuit

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.  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.  Wireless Baby Mo...

ZAGG has released a new universal tablet wireless keyboard. If you want more comfortable typing experience for your tablet or smartphone, the Bluetooth keyboard may be able to meet your requirements.This is a practical Bluetooth wireless keyboard that measures 9-5/4 x 5-1/2 x 3/4 inches and weights 0.65 lbs. As we can see from the images, the Bluetooth keyboard features elegant and ergonomic design, and comes with island-style keys in order to provide a comfortable, more natural typing experience and fast typing speed. Moreover, the portable speaker has a versatile protective case that doubles as a tablet stand for convenient set up and portability. Apart from that, its long-lasting battery offers you up to three months of regular use between charges. The universal tablet wireless keyboard is priced at $69.99 USD.  

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 metres. The circuit comprises transmitter and receiver sections. The communication between the transmitter and receiver sections is achieved through infrared signals. Fig. 1: Infrared transmitter 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 ring counter. Fig. 2:...

Battery-Powered portable unit, Suitable for all type Televisions Using this low-cost project one can reproduce audio from TV without disturbing others. It does not use any wire connection between TV and Loud Speaker. In place of a pair of wires, it uses invisible infra-red light to transmit audio signals from TV to Loud speakers, Without using any lens a range of up to 6 meters is possible. Range can be extended by using lenses and reflectors with IR sensors comprising transmitters and receivers. Transmitter's operation: IR transmitter uses two-stage transistor amplifier to drive two series-connected IR LEDs. An audio output transformer (T1) is used (in reverse) to couple audio output from TV to the IR transmitter. Transistors Q1 and Q2 amplify the audio signals received from TV through the audio transformer. Low impedance output windings (lower gauge or thicker wires) are used for connection to TV side while high-impedance windings are connected to IR transmitter. This IR transmit...