Switch Circuit

Automatic switch for batteries

Automatic switch for batteries

Nowadays the batteries are gaining more and more power, being the only components that fail to provide energy for portable electronic devices. The evolution is rapid, leading manufacturers electronic equipment to attempt to minimize the consumption of their products so that they can operate for several hours using simple batteries trade. In spite of the efforts of manufacturers, the device will absorb a zero power not yet invented. Thus, both small and if the current device is mathematically certain that at some point, after a few hours, days or ethdomades, the battery-drain '. The purpose of the circuit will describe below, is to keep 'alive' batteries for the maximum time, minimizing unnecessary consumption...

Touch Switch with MPF102 JFET

Touch Switch with MPF102 JFET

Q2 is held cut off since Q1 normally is conducting. When the touch plate is contacted by a large object (human body, etc.), stray 60-?? pickup is rectified by D1 and D2, and produces a negative voltage across R2-C2 and the gate of Q 1. Q1 cuts off, causes Q2 to conduct, and the output goes low. ..

Monostable to bistable relay with momentary switch

Monostable to bistable relay with momentary switch

This circuit could be used to drive a monostable relay by a singol momentary switch. Powered by 24 Volts it works for a 12 Volts relay. When the button is pressed Q1 is energized and the capacitor charges, while the relay coil is shorted. Once the button is released the relay turns on. Note that Q1 is powered by the capacitor until the relay switch (10-6) closes...

Delay Switch

Delay Switch

This switch allows the model train at such a station will automatically slow down. The train stands for a certain amount of time and then slowly pulls back. You do not own the train to stop. The relatively simple circuit works. P1 potentiometer for setting the waiting time, while turning to A caused a shorter waiting time and turn to B results in a longer waiting period. P2 is to set the brake and acceleratieweg. Here, too, turn to A results in faster acceleration and the train slows. ..

Delay switching for power amplifiers

Delay switching for power amplifiers

This delay can be used in power amplifiers, to prevent the fuses fail when the amplifier is turned on. The circuit is very simple with a relay which turned on when C2 and C3 are charged. If the relay has not been applied, the resistors used to control connected to feed. If after some time the relay attracts the bridge resistors. Watch out for your own safety when building this circuit. On the whole circuit is power. F1 should be the value of having the fuse that normally would be used...

Logic level relay controller

Logic level relay controller

The schematic below illustrates 4 methods of controlling a relay with a digital logic signal. Figure (A) can probably be used in most cases where the relay coil requires 100 mA or less and the input current is 2 milliamps or more. The resistor value (R) is determined from the input voltage and the available current. For example, a 5 volt input signal supplying 2 milliamps would require (5-.7)/.002 = 2150 ohms, or a 2.2K standard value. If the transistor has a minimum current gain of 50, there will be 100 mA of current available for the relay coil. ..

MOSFET Toggle Switching circuit

MOSFET Toggle Switching circuit

This circuit was adapted from the "Toggle Switch Debounced Pushbutton" by John Lundgren. It is useful where the load needs to be switched on from one location and switched off from another. Any number of momentary (N/O) switches or push buttons can be connected in parallel. The combination (10K, 10uF and diode) on the left side of the schematic insures the circuit powers up with the load turned off and the NPN transistor conducting. These components can be omitted if the initial power-on condition is not an issue. ..

MOSFET Toggle Relay

MOSFET Toggle Relay

This circuit is similar to the one above, but uses a N channel mosfet such as IRF530, 540, 640, etc. in place of the NPN transistor. Smaller mosfets could be used, but I don't know the part numbers. I tested the circuit with a IRF640, IRFZ44, IRFZ34 and REP50N06. The circuit has the same three advantages, it requires only a few parts, always comes up with the relay deactivated, and doesn't need any switch debouncing. In operation, when the relay is deactivated, the 100uF capacitor will charge to 6 volts. ..

IR 4 channels remote control with PIC12F629

IR 4 channels remote control with PIC12F629

The circuit above illustrates using the IR receiver module along with a PIC12F629 microcontroller to decode 5 individual IR remote control keys so the circuit will only toggle one of the 4 outputs when a particular key is pressed. The 5th key is assigned to the master clear function that toggles off the 4 outputs. Works with most hand held IR remote controls that send a single data stream. However, some remotes send multiple groups of data and only the first set of 40 bits or less will be recognized. This may result in the circuit responding to more than one key, or a single key may control more than one toggle switch...

Relay Toggle with 556 schematic

Relay Toggle with 556 schematic

This toggle circuit operates by using a couple 555 timers wired as inverters. Pins 2 and 6 are the threshold and trigger inputs to the first timer and pin 5 is the output. The output at pin 5 will always be the inverse of the input at pins 2 and 6. Likewise, the output at pin 9 of the second timer will always be the inverse of the input at pins 8 and 12. A 100K resistor connects the output of one inverter to the input of the other so the state of one will be the opposite of the other. ..

1 Transistor Toggle Relay schematic

1 Transistor Toggle Relay schematic

The circuit below requires a double pole, double throw relay in conjunction with a single transistor to allow toggling the relay with a momentary push button. One set of relay contacts is used to control the load, while the other is used to provide feedback to keep the relay activated or deactivated. Several push buttons can be wired in parallel to allow toggling the relay from different locations. In the deactivated state, the relay contacts are arranged so the 1000 uF capacitor will charge to about 2.7 volts. ..

Bistable Flip Flop with relay

Bistable Flip Flop with relay

Here are two examples of bistable flip flops which can be toggled between states with a single push button. When the button is pressed, the capacitor connected to the base of the conducting transistor will charge to a slightly higher voltage. When the button is released, the same capacitor will discharge back to the previous voltage causing the transistor to turn off. The rising voltage at the collector of the transistor that is turning off causes the opposite transistor to turn on and the circuit remains in a stable state until the next time the button is pressed and released. ..

Simple Monostable Flip Flop

Simple Monostable Flip Flop

The monostable flip flop, sometimes called a 'one shot' is used to produce a single pulse each time it is triggered. It can be used to debounce a mechanical switch so that only one rising and one falling edge occurs for each switch closure, or to produce a delay for timing applications. In the discrete circuit, the left transistor normally conducts while the right side is turned off. Pressing the switch grounds the base of the conducting transistor causing it to turn off which causes the collector voltage to rise. As the collector voltage rises, the capacitor begins to charge through the base of the opposite transistor, causing it to switch on and produce a low state at the output...

Set reset flip-flop circuit

Set reset flip-flop circuit

This is an example of a set/reset flip flop using discrete components. When power is applied, only one of the transistors will conduct causing the other to remain off. ..

Mono stable with 555 and relay

Mono stable with 555 and relay

The two circuits below illustrate using the 555 timer to close a relay for a predetermined amount of time by pressing a momentary N/O push button. The circuit on the left can be used for long time periods where the push button can be pressed and released before the end of the timing period. For shorter periods, a capacitor can be used to isolate the switch so that only the initial switch closure is seen by the timer input and the switch can remain closed for an unlimited period without effecting the output. ..

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