Wiring Material: switch

Showing posts with label switch. Show all posts

Wednesday, September 10, 2014

Infrared Switch

Infrared Switch schema for common use, please visit this page for complete explanation.

This is a single channel (on / off) universal switch that may be used with any Infra Red remote control using 36-38kHz. (This is a very common remote handset frequency). In place of IR1 a TSOP1738 receiver may be used.

Any "button" of any remote control may be used to work this universal switch. The button must be pressed for about one and a half seconds (determined by R3 and C2) before the relay will operate. The schema will remain in this state (latched) until reset. To reset, any button is pressed on the remote handset and held for a short duration.

For example, if you were watching TV, you could press and hold any button on the TV remote to trigger the schema. In order not to change channel, you could press the button of the channel you are watching. You can connect anything to the relay, for example a lamp, but make sure that the relay contacts can handle the rated voltage and current.

Tuesday, September 2, 2014

12v Light Dark Switch Wiring diagram Schematic

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 schema 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 schema is included to provide some hysteresis.

This keeps the schema 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 schema could control over 100 watts worth of 12v lighting. (July 22, 2008)

Source: DiscoverCircuits

Saturday, August 30, 2014

Video Switch for Intercom System Wiring diagram Schematic

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.

Circuit diagram :

Video Switch for Intercom System Circuit Diagram

Along with a video switch, the schema includes a video amplifier that has been used with good results in many other Elektor projects, which allows the brightness and the contrast to be adjusted separately. This amplifier is included because the distance between the street and the house may be rather large, so it is helpful to be able to compensate for cable attenuation in this manner. The switch stage is built around the well known 4060 IC, in which switches IC2a and IC2d alternately pass one of the two signals to the output. They are driven by switches IC2b and IC2c, which generate control signals that are 180 degrees out of phase. The switching rate for the video signals is determined by a clock signal from an ‘old standby’ 555 IC, which causes the signals to swap every 2 seconds with the speciﬁed com ponent values.

Naturally, this schema can also used in many other situations, such as where two cameras are needed for surveillance but only one video cable is available.

http://streampowers.blogspot.com/2012/06/video-switch-for-intercom-system_11.html

Wednesday, August 27, 2014

Solid State Switch For Dc Operated Gadgets

This solid state DC switch can be assembled using just three transistors and some passive components. It can be used to switch on one gadget while switching off the second gadget with momentary operation of switch. To reverse the operation, you just have to momentarily depress another switch.

The schema operates over 6V-15V DC supply voltage. It uses positive feedback from transistor T2 to transistor T1 to keep this transistor pair in latched state (on/ off), while the state of the third transistor stage is the complement of transistor T2’s conduction state.

Initially when switch S3 is closed, both transistors T1 and T2 are off, as no forward bias is available to these, while the base of transistor T3 is effectively grounded via resistors R8 and R6 (shunted by the load of the first gadget). As a result, transistor T3 is forward biased and gadget 2 gets the supply. This is indicated by glowing of LED2.

Solid-State Switch For Dc-Operated Gadgets Circuit diagram :

Solid-State Switch For Dc-Operated Gadgets Circuit Diagram

When switch S1 is momentarily depressed, T1 gets the base drive and it grounds the base of transistor T2 via resistor R4. Hence transistor T2 (pnp) also conducts. The positive voltage available at the collector of transistor T2 is fed back to the base of transistor T1 via resistor R3. Hence a latch is formed and transistor T2 (as also transistor T1) continues to conduct, which activates gadget 1 and LED1 glows.

Conduction of transistor T2 causes its collector to be pulled towards positive rail. Since the collector of T2 is connected to the base of pnp transistor T3, it causes transistor T3 to cut off, switching off the supply to gadget 2) as well as extinguishing LED2. This status is maintained until switch S2 is momentarily pressed. Depression of switch S2 effectively grounds the base of transistor T1, which cuts off and thus virtually opens the base-emitter schema of transistor T2 and thus cutting it off. This is the same condition as was obtained initially. This condition can be reversed by momentarily pressing switch S1 as explained earlier.

EFY lab note. During testing, it was noticed that for proper operation of the schema, gadget 1 must draw a current of more than 100 mA (i.e. the resistance of gadget 1 must be less than 220 ohms) to sustain the latched ‘on’ state. But this stipulation is not applicable for gadget 2. A maximum current of 275 mA could be drawn by any gadget.

Author : Praveen Shanker - Copyright : EFY

Tuesday, August 26, 2014

Simple Sound Operated Switch Wiring diagram Schematic

This is a Simple Sound Operated Switch Circuit Diagram. This sound-operated switch will sense the ring of the phone and translate this to a lamp that will go on and off. The amplified signal across R2 reaches D1 through capacitor C2. The rectified audio signals provide a negative bias for Q2, a pnp transistor. This causes Q2 to conduct so the current that triggers SCR1 is provided at the gate. Potentiometer R4 sets the sensitivity. R3 and C3 delay the operating voltage for Ql so that the schema will not be triggered on by the sound of the on/off switch, SI or by the current surge. Set the lamp atop a TV receiver, turn it on and set the potentiometer so that a finger snap at two feet will trigger the lamp on. Place the speaker close to the telephone and give it a try.

Simple Sound Operated Switch Circuit Diagram

Friday, August 15, 2014

Simple Switch Debouncer With Auto Repeat Wiring diagram Schematic

This is a Simple Switch Debouncer With Auto Repeat Circuit Diagram. This schema produces an output pulse when SW1 (pushbutton) is depressed. It also becomes a hysteresis gate oscillator. Dl and R2 add asymmetry. The DBRT (delay before repeat time) is caused by the oscillator start-up conditions: CI has to change from zero to the upper gate threshold rather than to the lower threshold. The auto repeat time: Gate hysteresis Â« 1 V for 74HCT14 gate, DBRT= 0.7T (upper gate threshold hysteresis). Upper gate threshold 2.3 V for HCT14, Ri<

Switch Debouncer With Auto Repeat Circuit Diagram

Sunday, August 10, 2014

Simple Automatic Load Sensing Power Switch

This schema will automatically switch on several mains-powered "slave" loads when a "master" load is turned on. For example, it will switch on the amplifier and CD player in a stereo system when the receiver is turned on. It works by sensing the current draw of the "master" device through a low value high wattage resistor using a comparator. The output of that comparator then switches on the "slave" relay. The schema can be built into a power bar, extension cord or power center to provide a convenient set of "smart" outlets that switch on when the master appliance is powered (turn on the computer monitor and the computer, printer and other peripherals come on as well).
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Simple Automatic Load Sensing Power Switch Circuit Diagram

Parts

Part	Total Qty.	Description
C1, C3	2	10uF 35V Electrolytic Capacitor
C2	1	1uF 35V Electrolytic Capacitor
R1	1	0.1 Ohm 10W Resistor
R2	1	27K 1/2W Resistor
R3, R4	1	1K 1/4W Resistor
R5	1	470K 1/4W Resistor
R6	1	4.7K 1/2W Resistor
R7	1	10K 1/4W Resistor
D1, D2, D4	3	1N4004 Rectifier Diode
D3	1	1N4744 15V 1 Watt Zener Diode
U1	1	LM358N Dual Op Amp IC
Q1	1	2N3904 NPN Transistor
K1	1	Relay, 12VDC Coil, 120VAC 10A Contacts
S1	1	SPST Switch 120AVC, 10A
MISC	1	Board, Wire, Socket For U1, Case, Mains Plug, Socket

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Notes

This schema is designed for 120V operation. For 240V operation, resistors R2 and R6 will need to be changed.
A maximum of 5A can be used as the master unless the wattage of R1 is increased S1 provides a manual bypass switch.
THis schema is not isolated from the mains supply. Because of this, you must exercise extreme caution when working around the schema if it is plugged in.