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SIMPLE RADIO FREQUENCY REMOTE SWITCHING CIRCUIT RF TRANSMITTER SECTION Today we are going to discuss about the simple RF (Radio Frequency) Transmitter and Receiver circuit. RF(Radio Frequency) is a High Frequency signal commonly used for communication applications, due to its high frequency we can transmit signal to a sufficient distance (about 300 Foots) without attenuation. Here, the simple RF switching circuit is used to turn ON and turn OFF an LED (For Demonstration) you can replace the LED with a switching RELAY and control any appliances. Read More.....

The circuit consists of power supply and control sections. The power supply section is built around transformer X1, bridge rectifier BR1 and filter capacitor C1. The 50Hz, 230V AC mains is stepped down by transformer X1 to deliver a secondary output of 9V, 300 mA. The transformer output is rectified by the bridge rectifier and filtered by capacitor C1. Fan and Air-Conditioner Control Switch circuit Diagram When the mains is switched on for the first time, pin 3 of IC CD4017 (IC1) goes high and relay RL1 energises to switch on the fan. When mains is briefly switched off using S1 and then switched on, the power to IC1 is maintained by the charge on capacitor C1. At the same time, there is a trigger pulse on the clock input (pin 14) of IC1, which advances the decade counter and relay RL2 energises to switch-on the air-conditioner. Both the air-conditioner and the fan will be turned off if the switch is in the ‘off’ position. Assemble the circuit on a general-purpose PCB and enclose in a s...

Now a day, everyone wants to control their appliance wirelessly (i.e. remote control). Here is a simple tested and inexpensive remote control switch utilizing reading available components.   Circuit Description of infrared (IR) remote control switch As in all wireless systems Infrared (IR) remote control switch also comprise two major section i.e. transmitter and receiver section. Transmitter Section: – The logic of this section is simple and is build around most versatile IC NE555 (IC 1 ), configured as astable multivibrator to produce frequency about 38 KHz. This is so, because IR module receiver used here works in range of 38 KHz frequency. Timing component of infrared remote control switch is resistor R 1 and R 2 and capacitor C 2 , determine the range of oscillating. Where, formula of generated frequency (F) from transmitter section IR remote is given by F = 1.443 / (R 1 + 2R 2 ) C2 The output frequency from pin 3 of IC 1 is fed to base of transistor T 1 through resistor ...

Often, for certain low voltage lighting systems; you would like to turn off the lights during the bright light of the day.  Most commercial day/night switches are designed for AC lighting.  This hobby circuit below was designed for a 12v DC system.  But, it could be modified for other voltage as well.  It uses an inexpensive photo-transistor as the light detector.  An n-channel FET is used to switch power to the lights.  A transistor circuit is included to provide some hysteresis.   This keeps the circuit from fluttering the light during the transition from day to night and night to day.  It is recommended that a plastic tube be placed over the transistor to prevent it from being illuminated by the lights it is controlling.  By selecting the appropriate power FET, the circuit could control over 100 watts worth of 12v lighting.   (July 22, 2008) Source: DiscoverCircuits

This circuit uses a Silcon Controlled Rectifier (SCR) as a latch switch. Once enabled it can only be turned off by pressing S2 or power is removed from the circuit. Latch Switch 2 Circuit Diagram Circuit Notes: The load is represented by the 1k resistor and orange LED, although the C106D can handle much larger loads. Once the On switch is pressed, the SCR receives a voltage on its gate terminal and goes into forward conduction and conducts current through its anode and cathode terminals. This current remains to flow even when the on switch is released, so the LED remains lit. The load can only be turned off by pressing the Reset switch which is a Push-to-Break non-latching push switch. Note that reset switch must be able to handle the full load currents and voltage.

Presettable times for train stops in stations are indispensable if you want to operate your model railway more or less realistically according to a timetable. This circuit shows how a 555 timer can be used with a relatively small timing capacitor to generate very long delay times as necessary by using a little trick (scarcely known among model railway electronic technicians): pulsed charging of the timing net-work. Such long delays can be used in hidden yards with through tracks, for instance.  As the timer is designed for half-wave operation, it requires only a single lead to the transformer and one to the switching track or reed contact when used with a Märklin AC system (H0 or H1). The other lead can be connected to any desired grounding point for the common ground of the track and lighting circuits. Circuit diagram : Long-Delay Stop Switch Circuit Diagram As seen from the outside, the timer acts as a monostable flip-flop. The output (pin 3) is low in the quiescent state. If a ...

This circuit will light a lamp at a remote location when the doorbell switch is pressed. This circuit should only be used with the solenoid type doorbells, the electronic type that play tunes will not work here.  It is quite easy to miss the sound of a doorbell if you are watching TV , this circuit gets round the problem by providing a visual indication. As an alternative, a LED could also be used. You could just parallel a lamp across the doorbell, but this would mean extra drain from the doorbell batteries or transformer. A series resistor, R1 is wired in series with the doorbell and reduces current flow, thereby increasing battery life. The value of R1 is chosen so that about 0.6 to 0.7 volts is developed across it, when the doorbell switch is pressed. I used a combination of a 22 ohm resistor in parallel with a 50 ohm. The voltage drop across R1 is sufficient to switch on the transistor, the lamp in series with the collector will then illuminate. I also used an electromechanica...

Simple and easy Video Switch for Intercom System Circuit Diagram. Nowadays a lot of intercom units are  equipped with video cameras so that you can  see as well as hear who is at the door. Unfortunately, the camera lens is perfectly placed  to serve as a sort of support point for people  during the conversation, with the result that  there’s hardly anything left see in the video  imagery.  One way to solve this problem is to install two cameras on the street side instead only  one, preferably some distance apart. If you  display the imagery from the two cameras  alternately, then at least half of the time you  will be able to see what is happening in front  of the door. Thanks to the video switch module described  here, which should be installed on the street  side not too far away from the two cameras,  you need only one monitor inside the house and you don’t need to install any additional video cables.   C...

Toggle switch in this article is a series of toggle switches that are controlled by infrared light. The series toggle switch is made from a combination of data flip-flop CD4013 2 units. Receiver circuit of the infrared light signals arranged with infrared receiver as found on television remote receiver. Infrared signal from remote is used as clock signals and data to the data flip-flop first. then the second flip-flop data set as a toggle flip-flop toggle the output signal is used to drive the relay. for more details can be seen in thethe following image . Series Toggle Switch With Infra Red (IR) that is required to supply voltage range of 12VDC and the output of Toggle Switch With Infra Red (IR) is dapt used to turn on the lights or other electronic devices with DC or AC voltage source. Series Toggle Switch With Infra Red (IR) was isolated from the load that is placed for use as the final relay. source [link] 

This is a Touch Switch with Digital Output Circuit Diagram control key by touch simple, it uses a 4011 IC. The output logic HI has its pulse delay time controlled by C1. In the case is C1 4.7uF controls the pulse width for 1 second, then the touched the plate. Nothing prevents you from being done tests with other values ​​of C1. Touch Switch with Digital Output Circuit Diagram

TOUCH SWITCH 1 This circuit detects the skin resistance of a finger to deliver a awfully tiny current to the super-alpha try of transistors to show the circuit ON. The output of the "super transistor" activates the BC 557 transistor. The voltage on the highest of the world is passed to the front of the circuit via the 4M7 to require the place of your finger and also the circuit remains ON.  To turn the circuit OFF, a finger on the OFF pads can activate the primary transistor and this may rob the "super transistor" of voltage and also the circuit can close up. TOUCH SWITCH-2 This circuit detects the skin resistance of a finger to show the circuit ON for concerning one second. The output are often taken to a counting circuit. The circuit consumes no current when in quiescent mode: http://streampowers.blogspot.com/2012/07/touch-switchs.html 

Certain industrial controls require accurate switching operations. For example, in case of a foot-switch for precise drilling work, even a small error in switching may cause considerable loss. This low-cost but accurate foot-operated switch can prevent that. IC NE555 is wired in one-shot mode. Its output pin 3 goes high only when both switches S1 and S2 are pressed simultaneously. You can release any one of the switches without changing the output state. When you release both the switches, the output goes low. Simple Accurate Foot-Switch Circuit Diagram The switches are placed under a foot paddle as shown in Fig. 2. LED1 is used as a warning indicator. If either S1 or S2 gets pressed erroneously, LED1 blinks to warn the operator. The operator can then withdraw his foot in case of a mistake or depress the other switch also to trigger the circuit. LED1 is to be mounted on the operator’s desk. The circuit operation is simple. Resistors R2, R3 and R4 form a voltage divider. IC NE555 has tw...

Small and simple circuit, Suitable for home appliances Normally home appliances are controlled by means of switches, sensors, etc. However, physical contact with switches may be dangerous if there is any shorting. The circuit described here requires no physical contact for operating the appliance. You just need to move your hand between the infrared LED (D2) and the phototransistor (Q1). The infrared rays transmitted by D2 is detected by the phototransistor to activate the hidden lock, flush system, hand dryer or else. This circuit is very stable and sensitive compared to other AC appliance control circuits. It is simple, compact and cheap. Current consumption is low in milliamperes. The circuit is built around an IC CA3140, D2, phototransistor and other discrete components. Circuit Diagram: Parts: R1 = 470R R2 = 100K R3 = 3.3K R4 = 10K D1 = 1N4007 D2 = IR LED Q1 = L14F1 RL = 5Vdc Relay IC = CA3140 Q2 = BC548 Circuit Operation: When regulated 5V is connected to the circuit, D2 emits i...

Build a Flashing Light with Twilight Switch Circuit Diagram . Flashing light is very useful in order to indicate any obstruction or working in progress. The project automatic flashing light with twilight switch flash light in dark but during day it automatically turns off itself. The circuit diagram of automatic flashing light with twilight switch is shown below where LDR is used as sensor. In the presence of light LDR offer low resistance and in dark it offers high resistance. When there is absence light, LDR offer high resistances which turn off the transistor T1. Due to this darlington pair made from transistor T2 and T3 is turn on which further glow bulb. The feedback from its output is given to the junction of resistor R2 and LDR as shown in circuit diagram. Due to feedback this circuit works as oscillator which work as flasher. Variable resistor VR1 is used to adjust the sensitivity of LDR. Flashing Light with Twilight Switch Circuit Diagram PARTS LIST Resistors (all ¼-watt, ± 5%...

Audio Controlled Mains Switch Circuit Diagram. It is often useful for audio or video equipment to be switched off automatically after there has been no input signal for a while. The function of the on-off switch in such equipment is then taken over by switch S2 in the accompanying diagram. It remains, however, possible to  switch off manually by means of Si. Automatic  switch-off occurs after there has been no input  signal for about 2 minutes: this delay makes it possible for a new record or cassette to be placed in the  relevant machine.   The audio input to the proposed circuit may be  taken from the output of the relevant TV set, amplifier, or whatever. The input earth is held at + 6 V  with respect to the circuit earth by potential divider  Ri-R2-R3-R4. The two 741s function as comparators: the output of ICi goes high when the in- put signal is greater than + 50 mV, whereas the out- put of IC2 goes high when the input signal  becomes mor...

The circuit above is  a circuit of drivers to control high voltage using the relay. Relay is controlled by an NPN transistor , its that works on 5V voltage and has diode in it, if the relay does not have s diode should be given with diode 1N4007 . Pin relay to  move the switch connected to V+ 5V and other is connected from driver NPN transistor , the base od the transistor may have input such us from circuit of infrared to control the distance, or with some other input. After the transistor was input  and the collector had output a voltage of the switch relay will work, and voltage that in switch relay ready to use. To cut off switch eliminates enough voltage input at the base transistor , the collector will not remove the voltage , and switch are automatically disconnected.

This is the 12v Light / Dark Switch Circuit Diagram. Often, for certain low voltage lighting systems; you would like to turn off the lights during the bright light of the day.  Most commercial day/night switches are designed for AC lighting.  This hobby circuit below was designed for a 12v DC system.  But, it could be modified for other voltage as well.  It uses an inexpensive photo-transistor as the light detector.  An n-channel FET is used to switch power to the lights.  A transistor circuit is included to provide some hysteresis.   This keeps the circuit from fluttering the light during the transition from day to night and night to day.  It is recommended that a plastic tube be placed over the transistor to prevent it from being illuminated by the lights it is controlling.  By selecting the appropriate power FET, the circuit could control over 100 watts worth of 12v lighting.   (July 22, 2008) 12v Light / Dark Switch Circuit...