Showing posts with label switch. Show all posts
Showing posts with label switch. Show all posts
Thursday, September 5, 2013
Sound Operated Switch Circuit
Circuit Diagram
Notes:
- This sensitive sound operated switch can be used with a dynamic microphone insert as above, or be used with an electret (ECM) microphone. If an ECM is used then R1 (shown dotted) will need to be included. A suitable value would be between 2.2k and 10kohms.
- The two BC109C transitors form an audio preamp, the gain of which is controlled by the 10k preset. The output is further amplified by a BC182B transistor. To prevent instability the preamp is decoupled with a 100u capacitor and 1k resistor. The audio voltage at the collector of the BC182B is rectified by the two 1N4148 diodes and 4.7u capacitor. This dc voltage will
- directly drive the BC212B transistor and operate the relay and LED.
- It should be noted that this circuit does not "latch". The relay and LED operate momentarily in response to audio peaks.
Thursday, August 8, 2013
Multi Position Mains Switch
The circuit shown here was born out of necessity after one of our colleagues had just renovated his kitchen and realized afterwards that there were not enough switches. Obviously he was not too keen to partially demolish the kitchen to install a few additional wires in the already tiled wall. That’s how the idea arose to develop a clever electronic circuit that would operate two lamps with only one switch. All this appeared to be easy to realize by adding a small circuit, consisting of a decade counter, a diode network, two relays and a low voltage power supply.
The schematic shows how simple the design of the ‘multi-position‘ extension really is. K3 is connected to the switched wires that go to the original light. K1 and K2 are the connections for the two new lamps. The operation is simply based on the fact that at every low to high transition at the CLK input of IC1 the active output moves over by one position. In combination with the diode network D4 through D7 this ensures that with a single wall switch it becomes possible to control two outputs. When the mains voltage is applied to K3 for the first time, Q0 will be high and Re1 will be energized.
When the mains switch is briefly switched off and then on again it will have no consequences for the 9-V power supply, because C4 is quite large. But this will result in a trigger pulse on the CLK input, so that Q1 will now be high and via D5 and D6 both relays are energised. After another off/on cycle of the mains switch, Q2 will be high, relay Re1 will de-energise and only Re2 is still activated. If we repeat the off/on cycle once more we’re back at the starting position and only Re1 is energized.
If the switch remains in the ‘off’ position then both relays will also be off. A printed circuit board has been designed for this extension so that the entire circuit will fit without any problems in a waterproof enclosure from OKW, Bopla or Schyller. The 9V transformer is also fitted on the PCB. PCB screw terminals can be used for K1, K2 and K3. Since the circuit is directly connected to the mains voltage we emphasis that the well-known safety rules need to be observed. When making any measurements or performing other operations on the circuit is it absolutely necessary to first break the connection to K3!
Resistors:
ReadMore....
The schematic shows how simple the design of the ‘multi-position‘ extension really is. K3 is connected to the switched wires that go to the original light. K1 and K2 are the connections for the two new lamps. The operation is simply based on the fact that at every low to high transition at the CLK input of IC1 the active output moves over by one position. In combination with the diode network D4 through D7 this ensures that with a single wall switch it becomes possible to control two outputs. When the mains voltage is applied to K3 for the first time, Q0 will be high and Re1 will be energized.
When the mains switch is briefly switched off and then on again it will have no consequences for the 9-V power supply, because C4 is quite large. But this will result in a trigger pulse on the CLK input, so that Q1 will now be high and via D5 and D6 both relays are energised. After another off/on cycle of the mains switch, Q2 will be high, relay Re1 will de-energise and only Re2 is still activated. If we repeat the off/on cycle once more we’re back at the starting position and only Re1 is energized.
If the switch remains in the ‘off’ position then both relays will also be off. A printed circuit board has been designed for this extension so that the entire circuit will fit without any problems in a waterproof enclosure from OKW, Bopla or Schyller. The 9V transformer is also fitted on the PCB. PCB screw terminals can be used for K1, K2 and K3. Since the circuit is directly connected to the mains voltage we emphasis that the well-known safety rules need to be observed. When making any measurements or performing other operations on the circuit is it absolutely necessary to first break the connection to K3!
Resistors:- R1,R2 = 10kΩ
- R3 = 33kΩ
- R4 = 100kΩ
- R5 = 10kΩ
- C1 = 100nF
- C2 = 10µF 63V
- C3 = 4µF7 63V radial
- C4 = 470µF 16V radial
- C5 = 2µF2 63V axial
- D1-D7 = 1N4148
- D8 = 1N4001
- T2,T3 = BC547B
- IC1 = 4017
- IC2 = 78L09
- K1,K2,K3 = 2-way PCB
- terminal block, lead pitch 7.5mm
- T r1 = mains transformer 9V 1.5VA
- B1 = B80C1500 (round case) (80V piv, 1.5A)
- Re1, Re2 = 12V relay
Friday, April 12, 2013
ATX Power Switch Substitute
An additional push-button switch is normally required for the ATX Power Switch/Soft Power Switch signal, but you can do without it if you use this simple circuit. It is an artful design, but it has been repeatedly tested. The zener diode is intended to provide protection against excessive voltages and reverse-polarity connection. In the latter case, the resulting short-circuit current (approximately 1A) will exceed the allowable limit and cause the ATX power supply to shut down after around five seconds. It might be possible to use a smaller capacitor; this must be tested experimentally in actual use.
If the motherboard documentation is poor, you should verify the earth pin using a continuity tester. The resistor is only needed if you want to be able to switch on the PC within ten seconds after switching it off. It discharges the capacitor quickly enough to make this possible. With a 1-kΩ resistor, the time constant is around 0.5 s. Since the capacitor also tends to stabilize the voltage, this circuit could also help in situations in which the ATX power supply switches off unintentionally due to voltage fluctuations on the PWR Supply On line.
ReadMore....
If the motherboard documentation is poor, you should verify the earth pin using a continuity tester. The resistor is only needed if you want to be able to switch on the PC within ten seconds after switching it off. It discharges the capacitor quickly enough to make this possible. With a 1-kΩ resistor, the time constant is around 0.5 s. Since the capacitor also tends to stabilize the voltage, this circuit could also help in situations in which the ATX power supply switches off unintentionally due to voltage fluctuations on the PWR Supply On line.
Thursday, April 11, 2013
Electronic Touch Switch
Mechanical contacts have the disadvantage that they wear out. That is why it is practical to use an electronic ‘touch switch’ in some situations. With such a touch switch the resistance of the human skin is used for the switching action. The schematic shows the design of a circuit that senses the resistance of the skin and converts it into a useful switching signal. The touch switch contacts can be made from two small metal plates, rivets, nails, etcetera, which are placed close together on a non-conducting surface. In this circuit a comparator of the type LM393 has been used. In the idle state there is, via R1, a voltage equal to the power supply voltage on the non-inverting input of IC1a.
Because the inverting input of IC1a is set with R2 and D3 to D5 at the supply voltage minus 1.8 V, the open-collector output of IC1.a is, via R3, equal to the power supply voltage. This voltage is inverted by IC1.b. The voltage at the non-inverting input of IC1.b amounts to half the power supply voltage (through voltage divider R4 and R5) and is lower than the voltage on the inverting input.
Electronic Touch Switch Circuit diagram:
The output of IC1.b is therefore a ‘0’. If the two touch contacts are bridged with a finger, the voltage at the non-inverting input will become low enough to cause the comparator to toggle state. The moistness of the skin results in a resistance of 1 to 10 MR. If this circuit is used in the vicinity of equipment that’s connected to the mains, then it can be sufficient to touch only the upper contact to operate the switch, provided that the circuit has been earthed. The body then acts as an antenna which receives the 50 Hz (or 60 Hz) from the mains.
This is enough to toggle IC1.a at the same 50 Hz. C1/R3 prevent this 50 Hz from reaching the input of IC1b and provide a useable ‘pulse’ of about 10 s at the output of IC1.b. Note that a fly walking across the touch switch conducts enough to generate a switching signal. So do not operate important things with this circuit (such as the heating system or the garage door). Do not make the wires between the touch contacts and the circuit too long to prevent picking up interference. The power supply voltage for the circuit is not very critical. Any regulated DC voltage in the range from 6 to 20 V can be used.
Author: Heino Peters - Copyright: Elektor Electronics Magazine
Source : http://www.ecircuitslab.com/2011/06/electronic-touch-switch.html
Source : http://www.ecircuitslab.com/2011/06/electronic-touch-switch.html
Light Activated Switch Circuit Using LM311
This is a design circuit diagram of a light activated switch. This circuit is based on National Semiconductors comparator IC LM 311 and a LDR for operation. This is the figure of the circuit.
The circuit is based on a voltage comparator circuit wired around IC 1. The non-inverting in put of IC1 is given with a reference voltage of 6V using resistors R3 and R4. The input to the inverting input will be the voltage across the LDR that is light dependent. At darkness the resistance of the LDR will be high and so do the voltage across it. At this condition the voltage at the inverting input will be higher than the reference at non inverting pin and the out put of the comparator will be low(~o V). Adjust POT R1 to set the desired light intensity for switching the relay. For this illuminate the LDR with the desire intensity light.
The relay will be either on or off. Adjust POT R1 slowly so that the state of the relay changes. That’s it. Now the circuit is set for the given intensity of light. When the LDR is illuminated, its resistance drops and so do the voltage across it. Now the voltage at inverting input will be lower than that at non inverting input and the out put of the comparator goes high (~12 V). This makes transistor Q1 on and it drives the relay. As a result we get a relay switching according to the intensity of the light falling on the LDR.
You can use either a 12 V battery or a well regulated & filtered 12V DC mains operated power supply. The pin out of LM311 is also given together with the circuit diagram. The pin 5&6 (Balance & Balance/Strobe) of IC LM311 are shorted to minimize the chance of oscillations.
The circuit is based on a voltage comparator circuit wired around IC 1. The non-inverting in put of IC1 is given with a reference voltage of 6V using resistors R3 and R4. The input to the inverting input will be the voltage across the LDR that is light dependent. At darkness the resistance of the LDR will be high and so do the voltage across it. At this condition the voltage at the inverting input will be higher than the reference at non inverting pin and the out put of the comparator will be low(~o V). Adjust POT R1 to set the desired light intensity for switching the relay. For this illuminate the LDR with the desire intensity light.
The relay will be either on or off. Adjust POT R1 slowly so that the state of the relay changes. That’s it. Now the circuit is set for the given intensity of light. When the LDR is illuminated, its resistance drops and so do the voltage across it. Now the voltage at inverting input will be lower than that at non inverting input and the out put of the comparator goes high (~12 V). This makes transistor Q1 on and it drives the relay. As a result we get a relay switching according to the intensity of the light falling on the LDR.
You can use either a 12 V battery or a well regulated & filtered 12V DC mains operated power supply. The pin out of LM311 is also given together with the circuit diagram. The pin 5&6 (Balance & Balance/Strobe) of IC LM311 are shorted to minimize the chance of oscillations.
Tuesday, April 9, 2013
Touch Switch Using FET
The series of touch this switch be an Touch Switch made using FET. This circuit serves to activate electronic devices only when we touch touch sensors.
Once we release a touch to the sensor, the electronic device that is connected is turned off again. The series of touch switch or touch switch is very simple, composed only of a FET, resistor and capacitor. The series of touch switches / touch switches work with source voltage 12VDC. Detailed series of touch switches / touch switch can be seen in thethe following figure .
Once we release a touch to the sensor, the electronic device that is connected is turned off again. The series of touch switch or touch switch is very simple, composed only of a FET, resistor and capacitor. The series of touch switches / touch switches work with source voltage 12VDC. Detailed series of touch switches / touch switch can be seen in thethe following figure .
FET Touch Switch
The series of touch switches / touch switch can only be used to illuminate DC, 12V DC lamp when it replaced the relay, the circuit can be used safely to load the AC network. Sensor touch to this series was made with 2 pieces of plate are arranged close together (within 1-2mm).
Friday, April 5, 2013
Intelligent Trailing Switch Circuit
This is a design effective circuit in which the equipments connected at the so called trailing sockets will run only if the equipment connected at the control socket is switched on. For example, let’s connect a motor is connected to the control socket and a lamp is connected at the trailing socket. The lamp will glow only when the motor is running. This is the figure of the circuit.
Explanation of the operation circuit is when the load connected at the control circuit is switched on, the load current flows through the diodes and as a result there will a voltage drop across the diodes. This voltage drop is sufficient enough to switch on the sensitive triac T1 and the equipments connected at the trailing sockets gets power supply. The components R2 and C1 forms a snubber circuit which protects the triac from transient fluctuations. The triac T1 must be a 600V, 8A, high sensitive gate type like TIC 225M. Fit the triac with a heat sink. The maximum load that can be connected at the trailing socket is 1000W. Take at most care while handling this circuit as it is connected to 230V AC.
Almost all equipments like motors, drills, blenders, fan, old TV, radio, amplifiers etc can be connected at the control socket. In case of modern TV, computers, amplifiers, etc the power switch does not completely isolate the equipment and the equipment will draw a small amount of current in the standby mode which is sufficient enough to trigger the triac. Such equipments cannot be used on the control socket because it makes the trailing equipments ON even if the control equipment is OFF.
Explanation of the operation circuit is when the load connected at the control circuit is switched on, the load current flows through the diodes and as a result there will a voltage drop across the diodes. This voltage drop is sufficient enough to switch on the sensitive triac T1 and the equipments connected at the trailing sockets gets power supply. The components R2 and C1 forms a snubber circuit which protects the triac from transient fluctuations. The triac T1 must be a 600V, 8A, high sensitive gate type like TIC 225M. Fit the triac with a heat sink. The maximum load that can be connected at the trailing socket is 1000W. Take at most care while handling this circuit as it is connected to 230V AC.
Almost all equipments like motors, drills, blenders, fan, old TV, radio, amplifiers etc can be connected at the control socket. In case of modern TV, computers, amplifiers, etc the power switch does not completely isolate the equipment and the equipment will draw a small amount of current in the standby mode which is sufficient enough to trigger the triac. Such equipments cannot be used on the control socket because it makes the trailing equipments ON even if the control equipment is OFF.
Subscribe to:
Posts (Atom)