Low Voltage Remote Mains Switch

This circuit allows a 240V mains appliance to be controlled remotely via low-voltage cabling and a pushbutton switch. The mains appliance (in this case, a light bulb) is switched with a suitably-rated relay. All of the electronics is housed in an ABS box located in proximity to the appliance. The pushbutton switch and plugpack are located remotely and can be wired up with 3-core alarm cable or similar. Cable lengths of 20m or more are feasible with this arrangement. When the switch (S1) is pressed, the input (pin 8) of IC1c is briefly pulled low via the 10mF capacitor, which is initially discharged.

The output (pin 10) immediately goes high and this is inverted and fed back to the second input (pin 9) via another gate in the quad NAND package (IC1d). In conjunction with the 1MW resistor and 470nF capacitor, IC1d eliminates the effects of contact "bounce" by ensuring that IC1c’s output remains high for a predetermined period. The output from IC1c drives the clock input of a 4013 D-type flip-flop (IC2). The flipflop is wired for a "toggle" function by virtue of the Q-bar connection back to the D input. A 2.2MW resistor and 100nF capacitor improve circuit noise immunity. Each time the switch is pressed, the flipflop output (pin 13) toggles, switching the transistor (Q1) and relay on or off. Note that all mains wiring must be properly installed and completely insulated so that there is no possibility of it contacting the low-voltage side of the circuit.

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2007 Toyota FJ Cruiser Stop Light Switch Wiring Diagram

,This is a duplex system that transmits two signals: STP and ST1-.The ECM Uses these signals to monitor the brake, whether or not the brake system is working properly. There ‘s only one signal to be detected at one time, this is either signal which is indicate the brake pedal is being depressed or the signal which is indicate that the brake pedal is being released. If the both signals are detected simultaneously, the ECM intrepets this as a malfunction in the light switch and sets the DTC. The Wiring Diagram below shows the Toyota FJ Cruiser Stop Light Switch Wiring Diagram.

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Remote controlled appliance switch circuit

Here is a versatile remote controlled appliance switch that can ON or OFF any appliance connected to it using a TV remote.IR remote sensor IC TSOP 1738 is used for receiving the signal. Normally when no signal is falling on IC3 the output of it will be high.This makes Q1 OFF.When a signal of 38 KHz from the TV remote falls on the IC3 its output goes low.This makes Q1 conduct and a negative pulse is obtained at pin 2 of IC 1 NE 555.Due to this IC1 wired as a monostable multivibrator produces a 4 Sec long high signal at its out put.This high out put is the clock for IC 2 which is wired as a Flipflop and of , its two outputs pin 3
goes low and pin 2 goes high.The high output at pin 2 is amplified to drive the relay .For the next signal the outputs of IC2 toggles state. Result, we get a relay toggling on each press on the remote.Any appliance connected to this circuit can be switched ON or OFF.

* Before wiring the circuit make sure that the carrier frequency of the
TV remote you have is 38 kHz.For that wire the sensor part only ,point your
remote to the TSOP1738 and press any switch.If out put of TSOP1738 goes
low then OK, your remote is of 38Khz type.Nothing to worry almost all TV
remote are of this type.

* You can use any switch of the remote because for any switch the code only changes,
the carrier frequency remains same.We need this carrier frequency only.

* Assemble the circuit on a good quality PCB or common board.

* The appliance can be connected through NO or NC and C contacts of the relay .

* Use a regulated 6V power supply for the circuit.

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Simple Remote Doorbell Warning Switch Circuit

This circuit should only be used with the solenoid type chime doorbells, the electronic type that play tunes will not work here. This is the simple circuit design.


The basic principle work is the hardest part for this circuit was the title. It is quite easy to miss the sound of a doorbell if you are watching the television, this circuit gets round the problem by providing a visual indication, i.e. a lamp. 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.

Using a series resistor R1 actually reduces current flow, and if run from batteries, will give them a longer life. The value of R1 is chosen so that about 0.6 to 0.7 volts is dropped across it, and the doorbell should still ring. I used a combination of a 22 ohm resistor in parallel with a 50 ohm. The doorbell still rang and circuit operated correctly. I used to have an electromechanical counter that registered each time when someone pressed the switch.

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Temperature Controlled Switch Circuit Diagram

It sounds
rather mysterious: a switch that is controlled by its ambient
temperature. All without the touch of a human hand, except for when
you’re building this sort of electronic thermostat. There are a lot of
handy uses for a thermally controlled switch. If the temperature inside
your PC gets too high sometimes, the circuit can switch on an extra
fan. You can also use to switch on an electric heater automatically if
the room temperature is too low. There are innumerable potential
applications for the thermostat described here.

Circuit diagram:

Temperature-Controlled Switch Circuit Diagram

There
are lots of ways to measure the temperature of an object. One very
simple way is to use a semiconductor sensor, such as the National
Semiconductor LM35 IC. This sensor is accurate to within 0.5 °C at 25
ºC, and few other sensors can do better or even come close to this level
of accuracy. In the circuit described here, the sensor (IC2) generates
an output voltage of 10 mV/°C, so the minimum temperature that can be
measured is 0 °C. At 25 °C, the output voltage of the sensor is (25 °C ×
10 mV/°C) = 0.25 V.

The circuit uses a TLC271 opamp as a
comparator. It compares the voltage from the temperature sensor, which
is connected to its non-inverting input (pin 3), with the voltage on its
inverting input (pin 2). The latter voltage can be set with
potentiometer P1. If the voltage from the sensor rises above the
reference value set by P1 (which represents the desired temperature),
the output of the comparator toggles to the full supply voltage level.
The output is fed to transistor T1, which acts as a switch so the output
can handle more current.

This makes it possible to energize a
relay in order to switch a heavy load or a higher voltage. The
transistor also supplies current to LED D1, which indicates whether the
temperature is above the reference value. The reference value can be
adjusted by P1 over the range of 18–30 °C with the indicated component
values. Of course, you can adjust the range to suit your needs by
modifying the value of R1 and/or R2. To prevent instability in the
vicinity of the reference value, a small amount of hysteresis is
provided by resistor R4 so the temperature will have to continue rising
or falling by a small amount (approximately 0.5 °C) before the output
state changes.

The LM35 is available in several different
versions. All versions have a rated temperature range of at least 0–100
°C. One thing you may have to take into account is that the sensor has a
relatively long response time. According to the datasheet, the sensor
takes 3 minutes to reach nearly 100% of its final value in still air.
The opamp has very low drift relative to its input voltages, and in the
low-power mode used here it draws very little current. The sensor also
draws very little current, so the total current consumption is less
than 80 µA when LED D1 is off.

The advantage of low current
consumption is that the circuit can be powered by a battery if necessary
(6 V, 9 V or 12 V). The sensor has a rated operating voltage range of
4–30 V, and the TLC271 is rated for a supply voltage of 3–16 V. The
circuit can thus work very well with a 12-V supply voltage, which means
you can also use it for car applications (at 14.4 V). In that case, you
must give additional attention to filtering out interference on the
supply voltage.
Source: Elektor Electronics 12-2010

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