Remote Operated Home Appliances Circuit

Suitable for operating, Lamps, Fan, Radio etc.., Small n easy unit

Here is the circuit diagram of Remote Operated Home Appliances or
Remote controlled Home appliances. Connect this circuit to any of your
home appliances (lamp, fan, radio, etc) to make the appliance turn
on/off from a TV, VCD, VCR, Air Conditioner or DVD
remote control. The circuit can be activated from up to 10 meters. It
is very easy to build and can be assembled on a veroboard or a
general-purpose PCB.

Circuit diagram:

Remote Control For Home Appliances

Remote Control For Home Appliances


  • R1 = 220K
  • R2 = 330R
  • R3 = 1K
  • R4 = 330R
  • R5 = 47R
  • C1 = 100uF-16V
  • C2 = 100nF-63V
  • C3 = 470uF-16V
  • D1 = 1N4007
  • D2 = Red LED
  • D3 = Green LED
  • Q1 = BC558
  • Q2 = BC548
  • IR = TSOP1738
  • IC1 = CD4017
  • RL1 = Relay 5V DC

Circuit Operation:
The 38kHz infrared rays generated by the remote control are received by
IR receiver module TSOP1738 of the circuit. Pin 1 of TSOP1738 is
connected to ground, pin 2 is connected to the power supply through R5
and the output is taken from pin 3. The output signal is amplified by
Q1. The amplified signal is fed to clock pin 14 of decade counter IC
CD4017 (IC1). Pin 8 of IC1 is grounded, pin 16 is connected to vcc and
pin 3 is connected to D2 (Red LED红包扫雷苹果下载地址), which glows to indicate that the appliance is ‘off.’

The output of IC1 is taken from its pin 2. D3 connected to pin 2 is
used to indicate the ‘on’ state of the appliance. Q2 connected to pin 2
of IC1 drives relay RL1. D1 acts as a freewheeling diode. The appliance
to be controlled is connected between the pole of the relay and neutral
terminal of mains. It gets connected to live terminal of AC mains via
normally opened (N/O) contact when the relay energizes. If you want to
operate a DC 12 volt relay then use a regulated DC 12 volt power supply
for DC 12 volt Relay and remember that the circuit voltage not be
红包扫雷苹果下载地址 exceeded more than DC 5 volts.

Circuit Keeps Wandering Children and Pets Nearby

The receiver circuit in
Figure 1 sounds an audio alarm when the transmitter (Figure 2) moves
beyond a designated perimeter. The transmitter, a voltage-controlled
oscillator, operates at approximately 915 MHz in the unlicensed ISM
(industrial/scientific/medical) band. It has a tuning voltage of
1.5V=3×R2/(R1+R2), which lets you easily adjust the frequency by varying
the values of resistors R1 and R2.

This 915 MHz receiver sounds an alarm when the comparator

This 915-MHz receiver sounds an alarm when the comparator’s inverting-input voltage drops below 400 mV.

The receiver comprises low-noise amplifier IC1, power detector IC2,
comparator IC3, and a buzzer. When the transmitter is within range—for
example, when a child or a pet is carrying it—the receiver detects the
RF signal and provides a voltage greater than 400 mV at the inverting
terminal of the comparator. Resistors R9 and R10 preset the reference
voltage at the comparator’s noninverting terminal. The reference voltage
红包扫雷苹果下载地址 is 3×R10/(R9+R10), and the comparator’s output remains low.

The transmitter comprises a voltage controlled oscillator, which R1 and R2 tune to approximately 915 MHz

The transmitter comprises a voltage-controlled oscillator, which R1 and R2 tune to approximately 915 MHz.

Circuit keeps wandering children and pets nearby figure 2When the
transmitter moves outside the predetermined boundary, the detected RF
produces less than 400 mV at the comparator. The comparator then
generates an output of approximately 3V, which turns on the buzzer and
sounds an alert that the transmitter has moved beyond the restricted
perimeter. To increase the detection range, you can place additional
low-noise amplifiers or VGAs (variable-gain
amplifiers) in front of the power detector. You can also increase or
decrease the desired perimeter by adjusting R10 to change the
红包扫雷苹果下载地址 comparator’s reference voltage.

RJ45 Network Card to IR Communication

This system, composed of
two opto-insulated circuits, allows the data transmission per infra-red
network device between two computers. For example, someone can transfer
his files starting from his desktop computer to his laptop computer
红包扫雷苹果下载地址 without using any cable. How?

By using infra-red diodes. We have to connect a circuit to the
10/100 Mbps network card of both computers by using a very small network
cable (can be smaller than 10 cm). One of the two extremities of the
cable must be removed to allow the wire connections. We must pay
红包扫雷苹果下载地址 attention when we do the connections.

The Tx+ output of any network card is connected to the input of the
Rx+ of the other with the cable. It’s the same way for the Tx- and the
Rx-. We have to supply the circuits with two sources of voltage. I
recommend to use a 9V battery and the +5V output of the power supply for
the desktop computer. The ground of the power supply must be connected
红包扫雷苹果下载地址 to the ground of the circuit.

For the laptop computer, I recommend to use a 9V battery and the
4.5V battery. All digital components must be of the 74H series because
these have short response times (less than 2.5 ns). All the GND
pins of the logic integrated circuits must be connected to the ground
of their circuit and their Vcc pin must be connected to the +Vcc of
红包扫雷苹果下载地址 their circuit.

300m FM Transmitter

This FM transmitter
circuit is very simple and it has a acceptable transmission . The signal
transited from this FM transmitter circuit can be received at almost
300 meters in open air .The circuit require a 3volts operating voltage
and can be tuned anywhere in the FM band.The coil should be about 3mm in
diameter and 5 turns. The wire is tinned copper wire, 0.61 mm in
diameter.After the coil in soldered into place spread the coils apart
about 0.5 to 1mm so that they are not touching.

Schematic for 3v FM transmitter

Schematic for 3v FM transmitter

If you don’t have a trim cap you can use a fixed value capacitor and
you can vary the TX frequency by adjusting the spacing of the coils or
placing a small piece of ferrite inside the coil , but the better way to
change the transmission frequency is to use a variable capacitor
.Connect a half or quarter wavelength antenna (length of wire) to the
aerial point. At an FM frequency of 100 MHz these lengths are 150 cm and
75 cm respectively.

IR Music Transmitter and Receiver

Using this circuit,
audio musical notes can be generated and heard up to a distance of 10
metres. The circuit can be divided into two parts: IR music transmitter
and receiver. The IR music transmitter works off a 9V battery, while the
IR music receiver works off regulated 9V to 12V. First diagram shows
the circuit of the IR music transmitter. It uses popular melody
generator IC UM66 (IC1) that can continuously generate musical tones.

Transmitter circuit diagram:

IR Transmitter Circuit

IR Transmitter Circuit Diagram

Receiver circuit diagram:

IR Receiver Circuit

IR Receiver Circuit Diagram

The melody generated by IC UM66 is transmitted through IR LEDs,
received by phototransistor ceived by phototransistor T3 and fed to pin
2 of IC µA741 (IC2). Its gain can be varied using potmeter VR1. The
output of IC µA741 is fed to IC LM386 (IC3) via capacitor C5 and
potmeter VR2. The melody produced is heard through the receiver’s
loudspeaker. Potmeter VR2 is used to control the volume of loudspeaker
红包扫雷苹果下载地址 LS1 (8-ohm, 1W). Switching off the power supply stops melody generation.

Author: Pardeep G – Copyright: EFY Mag

IR Remote Switch

Imagine the convenience
of selecting TV channels using your remote and then pointing the same
remote to your switchboard to switch on/off the fan or the tubelight.
Here is a simple circuit to remotely switch on/off any electrical device
through a relay using the normal TV/VCR/VCP/VCD remote control unit. It
works up to a distance of about 10 metres. The circuit is built around a
3-pin IR IC receiver (Siemens SFH-506-38 or
equivalent) that can detect 38kHz burst frequency generated by a TV
remote. (This IR receiver module has been covered earlier in many
projects published in this blog.) The output pin of IR sensor goes low
when it detects IR light, triggering the monostable (1-second) built
around timer NE555. The output of the mono toggles the J-K flip flop,
whose Q output drives the relay through SL100 npn transistor (T1).

IR Remote Switch

IR Remote Switch

LED2, LED3, and LED4 are used to display the status of each output stage during circuit operation. Back-EMF
diode D5 is used for protection. Transistor T1 is configured as an
open-collector output device to drive the relay rated at 12V DC. The
circuit draws the power from voltage regulator 7805. Capacitor C5 is
soldered close to the IR sensor’s pins to avoid noise and false
triggering. Capacitor C3 and resistor R3 also avoid false triggering of
monostable NE555. The monostable acts as a 1-second hysterisis unit to
restrict the flip-flop from getting retriggered within one second. To
activate any other 12V logic device, use the output across the relay
coil terminals.

Simple AM Radio Receiver

This circuit is
essentially an amplified crystal set. The inductor could be a standard
AM radio ferrite rod antenna while the tuning capacitor is a variable
plastic dielectric gang, intended for small AM radios. The aerial tuned
circuit feeds diode D1 which functions as the detector. A germanium type
is far preferable to a silicon signal diode because its lower forward
voltage enables it to work with smaller signals. The detected signal
from the diode is filtered to remove RF and the recovered audio is fed
to a 2-transistor stage which drives a set of 32O phones from a
Walkman-style player.

Simple AM Radio Receiver Circuit

Simple AM Radio Receiver Circuit Diagram

Author: Peter Goodwin
红包扫雷苹果下载地址 Copyright: Silicon Chip Electronics

Tuned Radio Frequency (TRF) Receiver

receivers have been mass-produced since around 1924, but for reasons of
cost did not become successful until the 1930s. Before the second world
war other, simpler receiver technologies such as the TRF
receiver and the regenerative receiver were still widespread. The
circuit described here is based on the old technology, but brought
up-to-date a The most important part of the circuit is the input stage,
where positive feedback is used to achieve good sensitivity and
selectivity. The first stage is adjusted so that it is not quite at the
point of oscillation. This increases the gain and the selectivity,
giving a narrow bandwidth.

To achieve this, the potentiometer connected to the drain of the FET
must be adjusted very carefully: optimal performance of the receiver
depends on its setting. In ideal conditions several strong stations
should be obtainable during the day using a 50 cm antenna. At night,
several times this number should be obtainable. The frequency range of
the receiver runs from 6 MHz to 8 MHz. This range covers the 49 m and
the 41 m shortwave bands in which many European stations broadcast. Not
bad for such a simple circuit! The circuit employs six transistors. The
first stage is a selective amplifier, followed by a transistor detector.
Two low-frequency amplifier stages complete the circuit.

Tuned Radio Frequency (TRF) Receiver Circuit

Tuned Radio Frequency (TRF) Receiver Circuit Diagram

The final stage is a push-pull arrangement for optimal drive of the
low-impedance loudspeaker. This circuit arrangement is sometimes called a
‘1V2 receiver’ (one preamplifier, one detector and two audio-frequency
stages). Setting-up is straightforward. Adjust P1 until the point is
reached where the circuit starts to oscillate: a whistle will be heard
from the loudspeaker. Now back off the potentiometer until the whistle
stops. The receiver can now be tuned to a broadcaster. Occasional
further adjustment of the potentiometer may be required after the
station is tuned in. The receiver operates from a supply voltage of
between 5 V and 12 V and uses very little current. A 9 V PP3 (6F22)
battery should give a very long life.

author: gert baars – copyright: elektor 2004

FM Booster

A low-cost circuit of an
FM booster that can be used to listen programs from distant FM stations
clearly. The circuit comprises a common-emitter tuned RF preamplifier
wired around VHF/UHF transistor 2SC2570 (
C2570). this FM booster circuit is constructed using few common
components( not require some special components ) and provide a very
good gain .to calibrate this circuit you need to adjust input/output
红包扫雷苹果下载地址 trimmers (VC1/VC2) for maximum gain.

Input coil L1 consists of four turns of 20SWG enamelled copper wire
(slightly space wound) over 5mm diameter former. It is tapped at the
first turn from ground lead side. Coil L2 is similar to L1, but has only
three turns. Both of the trimmers are 22pF value. This FM radio signal
booster needs to be powered by a 12 volts DC power supply .

Mobile Bug Detector

his handy, pocket-size
mobile transmission detector can sense the presence of an activated
mobile phone from a distance of one-and-a-half metres. So it can be used
to prevent use of mobile phones in examination halls, confidential
rooms, etc. It is also useful for detecting the use of mobile phone for
spying and unauthorised video transmission. The circuit can detect both
the incoming and outgoing calls, SMS and video transmission even if the mobile phone is kept in the silent mode.

The moment the bug detects RF transmission signal from an activated mobile phone, it starts sounding a beep alarm and the LED
blinks. The alarm continues until the signal transmission ceases. An
ordinary RF detector using tuned LC circuits is not suitable for
detecting signals in the GHz frequency band used in mobile phones. The
transmission frequency of mobile phones ranges from 0.9 to 3 GHz with a
wavelength of 3.3 to 10 cm. So a circuit detecting gigahertz signals is
required for a mobile bug.

Here the circuit uses a 0.22µF disk capacitor (C3) to capture the RF
signals from the mobile phone. The lead length of the capacitor is
fixed as 18 mm with a spacing of 8 mm between the leads to get the
desired frequency. The disk capacitor along with the leads acts as a
small gigahertz loop antenna to collect the RF signals from the mobile
phone. Op-amp IC CA3130 (IC1) is used in the circuit as a
current-to-voltage converter with capacitor C3 connected between its
inverting and non-inverting inputs.

It is a CMOS version using gate-protected p-channel MOSFET
transistors in the input to provide very high input impedance, very low
input current and very high speed of performance. The output CMOS
transistor is capable of swinging the output voltage to within 10 mV of
either supply voltage terminal. Capacitor C3 in conjunction with the
lead inductance acts as a transmission line that intercepts the signals
from the mobile phone. This capacitor creates a field, stores energy and
transfers the stored energy in the form of minute current to the inputs
of IC1.

Mobile Bug Detector Circuit

Mobile Bug Detector Circuit Diagram

This will upset the balanced input of IC1 and convert the current
into the corresponding output voltage. Capacitor C4 along with
high-value resistor R1 keeps the non-inverting input stable for easy
swing of the output to high state. Resistor R2 provides the discharge
path for capacitor C4. Feedback resistor R3 makes the inverting input
high when the output becomes high. Capacitor C5 (47pF) is connected
across ‘strobe’ (pin 8) and ‘null’ inputs (pin 1) of IC1 for phase
红包扫雷苹果下载地址 compensation and gain control to optimize the frequency response.

When the mobile phone signal is detected by C3, the output of IC1
becomes high and low alternately according to the frequency of the
signal as indicated by LED1. This triggers monostable timer IC2 through
capacitor C7. Capacitor C6 maintains the base bias of transistor T1 for
fast switching action. The low-value timing components R6 and C9 produce
very short time delay to avoid audio nuisance. Assemble the circuit on a
general-purpose PCB as compact as possible and enclose in a small box like junk mobile case.

As mentioned earlier, capacitor C3 should have a lead length of 18
mm with lead spacing of 8 mm. Carefully solder the capacitor in standing
position with equal spacing of the leads. The response can be optimized
by trimming the lead length of C3 for the desired frequency. You may
use a short telescopic type antenna. Use the miniature 12V battery of a
remote control and a small buzzer to make the gadget pocket-size. The
unit will give the warning indication if someone uses mobile phone
红包扫雷苹果下载地址 within a radius of 1.5 meters.

Author: D. Mohan Kumar – Copyright: EFY Magazine