Showing posts with label switch. Show all posts
Showing posts with label switch. Show all posts
Thursday, July 11, 2013
Simple Electronic Quiz Switch
One of the common rounds in the quizzes is the buzzer round. We are describing here a simple electronic circuit that can be used in any test or quiz competition. In this circuit, only four persons can participate, and every participant is assigned a certain number. Whenever a switch is pressed, the circuit locks the remaining three entries. At the same time, an alarm sounds and the designated switch number is displayed on the seven segment LED display.When a player presses his switch, the corresponding output of IC1 goes high. Let us suppose, when switch S1 is pressed, D1 input of IC1 goes low and its corresponding output Q1 goes high. As a result, current passes through D5 to piezo buzzer PZ1, which creates a beep. At the same time, current also passes through diodes D6-D7 to show the number on the LED display.
Circuit diagram:
Simple Electronic Quiz Switch Circuit Diagram
Similarly, when any other switch (S2-S4) is pressed, the corresponding number gets displayed on seven segment displaying DIS1 and buzzer sounds. Switch S5 is used to reset the display exclusively. Switch S5 is a push to on switch. The circuit is powered by 9V battery. Assemble the circuit on a general purpose PCB and enclose it in a suitable case along with seven segment display and piezo buzzer. The assembled circuit can be kept near the host and the switches connected through the external can be assigned to the players.
http://streampowers.blogspot.com/2012/06/simple-electronic-quiz-switch.html
Monday, July 8, 2013
Schematic 10 Way Electronic Switch
This is a 10 way electronic latching switch using just two switches. Each output can be latched on and off independently.
10 Way Electronic Switch Circuit Diagram
Notes
The schematic is shown above, and two switches S1 and S2 are used to control the outputs. The main work is done by U2 a CMOS4017 decade counter divider IC. At switch on, C1 is quickly charged by R4 and a brief reset pulse is applied to to the reset pins of both U1 and U2. This results in U1, a 7 segment display display driver and decade counter showing "zero" on the 7 segment display and pin 3 (which is the output zero) of the 4017 becoming high.
Each time S1 is pressed the clock input of U2 is incremented, by one count and the display and 4017 will cycle through all 10 outputs. A separate reset switch is not provided as the display reads the currently selected output.
When the 4017 is on a particular output, for example zero, then the controlled circuit can be turned on or off using switch S2. To latch the output a type JK flip-flop is used at each of the ten outputs. This works as follows. When the 4017 is at output zero, pin 3 will be high. This enables both JK inputs of the flip flop (U4A at output zero) and the circuit can then be toggled via pulses applied from switch S2. The Q output of each flip-flop drives and NPN transistor and then a small relay. The NPN transistors can be any general purpose type, e.g. 2N2222, BC108, BC548 etc. The relay allows external loads of different voltage and current to this circuit to be controlled.
For clarity, the schematic is drawn with outputs, zero, six and nine shown only. The pinouts for the CMOS ICs 4017 and 4026 can be found in the practical section.
The CMOS 4026 is available at ESR Electronics in the UK.
If required, the external circuits power supply can be used to power the driver transistor and relay. This is shown on output 6, the dotted lines representing the power coming from an external battery. The only other requirement here is that the external circuits common negative terminal is tied to this circuits common chassis (negative) terminal.
10 Way Electronic Switch Circuit Diagram
The schematic is shown above, and two switches S1 and S2 are used to control the outputs. The main work is done by U2 a CMOS4017 decade counter divider IC. At switch on, C1 is quickly charged by R4 and a brief reset pulse is applied to to the reset pins of both U1 and U2. This results in U1, a 7 segment display display driver and decade counter showing "zero" on the 7 segment display and pin 3 (which is the output zero) of the 4017 becoming high.
Each time S1 is pressed the clock input of U2 is incremented, by one count and the display and 4017 will cycle through all 10 outputs. A separate reset switch is not provided as the display reads the currently selected output.
When the 4017 is on a particular output, for example zero, then the controlled circuit can be turned on or off using switch S2. To latch the output a type JK flip-flop is used at each of the ten outputs. This works as follows. When the 4017 is at output zero, pin 3 will be high. This enables both JK inputs of the flip flop (U4A at output zero) and the circuit can then be toggled via pulses applied from switch S2. The Q output of each flip-flop drives and NPN transistor and then a small relay. The NPN transistors can be any general purpose type, e.g. 2N2222, BC108, BC548 etc. The relay allows external loads of different voltage and current to this circuit to be controlled.
For clarity, the schematic is drawn with outputs, zero, six and nine shown only. The pinouts for the CMOS ICs 4017 and 4026 can be found in the practical section.
The CMOS 4026 is available at ESR Electronics in the UK.
If required, the external circuits power supply can be used to power the driver transistor and relay. This is shown on output 6, the dotted lines representing the power coming from an external battery. The only other requirement here is that the external circuits common negative terminal is tied to this circuits common chassis (negative) terminal.
Sunday, July 7, 2013
Mini RS232 Data Switch
Only simple materials and a little bit of skill are needed to build an RS232 switch. All that you need are two 9-way sub-D plugs with solder pins, a small piece of sheet aluminium, two sets of screw retainer posts, a 4-pole double-throw switch, a strain relief sleeve and a suitable plastic connector shell for a 25-way sub-D connector, with both in-line and right-angle cable entries (such as Conrad Electronics #711322). What is important is that the side cable entry together with its associated strain relief leaves enough room for the switch. If necessary, you may have to cut away a few square millimetres of the sidewall or a few ribs of the plastic shell.
Project image :
Mini RS232 Data Switch Image
The switch is operated via the in-line cable opening, as can be seen from the photo. A suitable switch with an overall length of 29 mm can be found in the Conrad catalogue under order number 708232. The only modification that must be made to the connector shell is to drill two holes for the retaining screws for the switch (M2.6 screws) at a spacing of 24 mm.
Circuit diagram :
Mini RS232 Data Switch Circuit Diagram
Connect the two sub-D connectors together using the piece of aluminium and the screw retainer posts. Then solder the cable to the connectors and the switch as indicated. The two connectors are wired somewhat differently. While the upper sub-D plug is connected 1:1 with the input cable (with the switch in the appropriate position), the DCD, DTR, DSR and RI pins of the lower connector are left open. This is because RTS and CTS are fully sufficient for handshaking, as long as DTR and DSR are connected to each other. The only leads that are switched are RXD, RTS, TSD and CTS. The ground potential is fed from the cable to both connectors. After everything has been properly soldered together, you can fit everything into the cable shell as shown.
http://streampowers.blogspot.com/2012/06/mini-rs232-data-switch.html
Cell Phone Controlled Audio Video Mute Switch
This cell-phone-controlled audio/ video mute switch is highly useful in automobiles. The circuit automatically disconnects power supply to the audio/video system whenever the mobile handset is lifted off the holder for making or receiving a call. You can use any readily available cell-phone holder with some mi-nor alterations or fabricate it yourself as shown in Fig. 1.
Fig. 1: Proposed cell-phone holder The circuit is wired around IC LM555 (IC1), the CMOS version of timer NE555, as shown in Fig. 2. IC1 is used as a medium current line driver with either an inverting or non-inverting output. It can sink (or source) current of up to 50 mA only, so take care while handling it. The audio/video system is connected to the circuit via normally opened (N/O) contacts of the relay.
Fig. 2: The circuit of the cell phone-controlled audio/video mute switch When the cell phone is in its holder, LDR1 does not receive any light from white LED1 and its resistance is high. As a result, the voltage at pin 2 of IC1 re-mains high to provide a low output at pin 3. The low output of IC1 activates relay RL1 and the audio/video system gets power supply via its N/O contacts. LED3 glows to indicate that the audio/video system is ‘on.’ When the handset is taken off the holder, light rays from LED1 fall on LDR1 and its resistance decreases.
As a result, the voltage at pin 2 of IC1 de-creases to provide a high output at its pin 3. The high output of IC1 deactivates relay RL1 and the audio/video system does not get power supply. LED2 glows to indicate that the audio/video system is ‘off.’ Preset VR1 is used to control the sensitivity of the circuit. Zener diode ZD1 is used for protecting white LED1 from the higher voltage. The circuit works off a 12V car battery. Switch S1 can be used to manually switch on/off the audio/video system.
http://streampowers.blogspot.com/2012/06/cell-phone-controlled-audiovideo-mute.html
Wednesday, July 3, 2013
AC Mains Bistable Switch
This AC mains-operated bistable switch turns on or turns off a device using a miniature neon lamp and a few discrete components. This switch can be used for control pan-els, appliances and lighting controls. A push-to-on switch is used to light up the neon lamp. The light emit-ted by the neon lamp, in turn, enables the switching action of the circuit. Use of a 555 timer wired for bistable operation makes the circuit act as a bistable switch.
Circuit diagram :
AC Mains Bistable Switch Circuit Diagram
The neon lamp (NL1) and the push-to-on switch (S1) are directly connected to 230V AC mains. The 12V DC supply for timer 555 (IC1) is derived from 230V AC mains through capacitive dropper C1, resistor R1 and a 12V zener diode. IC1 works as a flip-flop circuit, with the signal at its output pin 3 toggling every time it receives a pulse at its pins 2 and 6.
The operation of the circuit is simple. When you press switch S1 momentarily, the neon lamp glows, making phototransistor T1 conduct to provide a pulse at pins 2 and 6 of IC1. When switch S1 is pressed, the output of IC1 goes high and LED1 glows. Pressing S1 again makes the output of IC1 low and LED1 stops glowing.
In place of LED1, you can use an optodiac or suitable relay (not shown in the circuit) along with a suitable driver circuit to drive AC loads. Assemble the circuit on a general-purpose PCB with the neon lamp and the phototransistor housed in a small black tube isolated from the external light source, and enclose in a suitable cabinet. Fix switch S1 on the front panel of the cabinet, and mains power cord at the rear. At the rear, also fix a 3-pin socket to connect the AC load.
Caution. Take care when operating this circuit as it is directly connected to 230V AC mains. Better still, don’t attempt this circuit if you have no experience in handling high-voltage circuits.
http://streampowers.blogspot.com/2012/06/ac-mains-bistable-switch.html
Monday, June 3, 2013
Switch Lights Wiring Diagram
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Switch Light Power Switch.
Way Switch With Lights Wiring Diagram.
Way Switch Wiring Diagram Variation 6 Electrical Online.
Help With Fog Light Wiring Problem Ford Mustang Forums.
Way Switch Wiring Diagram Variation 6 Electrical Online.
Two Way Light Switch Using 3 Core Cable.
How To Wire Two Lights On One Switch Ehow Com.
Wednesday, April 10, 2013
Automatic TV Lighting Switch
The author is the happy owner of a television set with built-in Ambilight lighting in the living room. Unfortunately, the television set in the bedroom lacks this feature. To make up for this, the author attached a small lamp to the wall to provide background lighting, This makes watching television a good deal more enjoyable, but it ’s not the ideal solution. Although the TV set can be switched off with the remote control, you still have to get out of bed to switch off the lamp.
Automatic TV Lighting Switch Circuit diagram:
Consequently, the author devised this automatic lighting switch that switches the background light on and off along with the T V set. The entire circuit is fitted in series with the mains cable of the TV set, so there’s no need to tinker with the set. It works as follows: R1 senses the current drawn by the TV set. It has a maximum value of 50 mA in standby mode, rising to around 500 m A when the set is operating. The voltage across R1 is limited by D5 during negative half- cycles and by D1– D4 during positive half-cycles. T he voltage across these four diodes charges capacitor C1 via D6 during positive half-cycles. This voltage drives the internal LED of solid-state switch TRI1 via R2, which causes the internal triac to conduct and pass the mains voltage to the lamp. Diode D7 is not absolutely necessary, but it is recommended because the LED in the solid-state switch is not especially robust and cannot handle reverse polarisation. Fuse F1 protects the solid-state switch against overloads. T he value of use d here (10 Ω) for resistor R1 works nicely with an 82-cm (32 inch) LCD screen.
With smaller sets having lower power consumption, the value of R1 can be increased to 22 or 33 Ω, in which case you should use a 3-watt type. Avoid using an excessively high resistance, as otherwise TRI1 will switch on when the TV set is in standby mode. Some TV sets have a half-wave rectifier in the power supply, which places an unbalanced load on the AC power outlet. If the set only draws current on negative half-cycles, the cir-cuit won’t work properly. In countries with reversible AC power plugs you can correct the problem by simply reversing the plug. Compared with normal triacs, optically cou-pled solid-state relays have poor resistance to high switch-on currents (inrush currents).
For this reason, you should be careful with older-model TV sets with picture tubes (due to demagnetisation circuits). If the relay fails, it usually fails shorted, with the result that the TV background light remains on all the time. If you build this circuit on a piece of perf-board, you must remove all the copper next to conductors and components carrying mains voltage. Use PCB terminal blocks with a spacing of 7.5 mm. This way the separation between the connections on the solder side will also be 3 mm. If you fit the entire arrangement as a Class II device, all parts of the circuit at mains potential must have a separation of at least 6 mm from any metal enclosure or electrically conductive exterior parts that can be touched.
Author :Piet Germing - Copyright : Elektor
Source : http://www.ecircuitslab.com/2012/03/automatic-tv-lighting-switch.html
Tuesday, April 9, 2013
Triac Light Switch as a dimers
The series of light switches this time slightly different from the voltage of work. The series of light switches can work directly on the AC power network. Light switches are using the main component of TRIAC and LDR. The circuit is very simple and the components were sold in the market.
If you want a light reception sensitivity of this circuit can be arranged then the 3.3 MOhm resistor can be replaced with a variable resistor. For more details can be seen from the following series of images.
If you want a light reception sensitivity of this circuit can be arranged then the 3.3 MOhm resistor can be replaced with a variable resistor. For more details can be seen from the following series of images.
 |
| Circuit Diagram |
With Triac Light Switch series is as dimers, but dimers control performed by the reception of light around the LDR. The lower the intensity cayaha received LDR then bright lights. For installation LDR need to be considered so as not exposed to light from the lamp directly.
Wednesday, April 3, 2013
Photo Switch Circuit using 555 IC
Here’s a design circuit for simple photo switch suitable for home and industrial purpose. The circuit switches on a relay when the light intensity falling on the sensor crosses the set limit. The circuit is based on a NE 555 and two transistors for driving the relay. The resistor R1 is adjusted such a way that under normal condition the voltage across the LDR is less than 1/3 the supply voltage. In this condition output of IC is high.
This makes transistor Q1 on. Transistor Q2′s base is connected to collector of Q1. So Q2 will be off keeping the relay de energized. When light falls the voltage across LDR rises above 2/3 Vcc. This makes the output of IC go high making the relay to energized. The result we get a relay that operates according to the intensity of light falling on the LDR. To setup the circuit switch on power supply, connect a multi meter across LDR and adjust R1 so that voltage across LDR is just below 1/3 supply voltage. Ensure that relay is off in this condition. If not reduce voltage across LDR further more by adjusting R1 to make relay off.
Now cover the top of LDR using a black paper and see the relay gets activated. If not, make further adjustments with R1.Nothing to care after some trial and error you will get the correct set point of R1 where the circuit works. This circuit is nothing great, but some simple basics. I have tested this and got good results. So no problem .Just proceed. If there is some chattering in the relay , that may be because off the difference between the turning on and turning off voltages. This can be avoided by connecting a resistor whose value is equal to 1/2 the resistance of LDR at illuminated condition.
readmore...
This makes transistor Q1 on. Transistor Q2′s base is connected to collector of Q1. So Q2 will be off keeping the relay de energized. When light falls the voltage across LDR rises above 2/3 Vcc. This makes the output of IC go high making the relay to energized. The result we get a relay that operates according to the intensity of light falling on the LDR. To setup the circuit switch on power supply, connect a multi meter across LDR and adjust R1 so that voltage across LDR is just below 1/3 supply voltage. Ensure that relay is off in this condition. If not reduce voltage across LDR further more by adjusting R1 to make relay off.
Now cover the top of LDR using a black paper and see the relay gets activated. If not, make further adjustments with R1.Nothing to care after some trial and error you will get the correct set point of R1 where the circuit works. This circuit is nothing great, but some simple basics. I have tested this and got good results. So no problem .Just proceed. If there is some chattering in the relay , that may be because off the difference between the turning on and turning off voltages. This can be avoided by connecting a resistor whose value is equal to 1/2 the resistance of LDR at illuminated condition.
Tuesday, March 26, 2013
Vehicle Interior Lighting With Switch Off Delay
Nowadays, a switch-off delay for the vehicle interior lighting is a naturally a standard feature. However, with certain models having only spartan fittings, or older-model vehicles, you’re left sitting in the dark as soon as you climb in and close the door. That calls for an aftermarket accessory! The author built this circuit using ‘normal’ components (with leads), but in the SMD manner, which means fitting the components on the copper side. The only holes drilled in the circuit board were the four fixing holes, and the entire assembly was firmly attached to the surface of the heatsink for power transistor T3 (the author used a finned heat sink rated at 7.2 °C/W). The heatsink is at ground potential.
A value of 1 Ω was used for R3 with satisfactory operation of the darlington. The light goes on when the door is opened. After the door is closed, it continues to illuminate the interior of the car at full brightness for around 30 seconds,after which it slowly dims. Approximately 1 minute after the door is closed, the quiescent current drops to zero.
readmore...
A value of 1 Ω was used for R3 with satisfactory operation of the darlington. The light goes on when the door is opened. After the door is closed, it continues to illuminate the interior of the car at full brightness for around 30 seconds,after which it slowly dims. Approximately 1 minute after the door is closed, the quiescent current drops to zero.Sunday, March 24, 2013
USB Printer Share Switch
This simple device allows two computers to share a single USB printer or some other USB device, such as an external flash drive, memory card reader or scanner. A rotary switch selects the PC that you wish to use with the USB device, while two LEDs indicate the selected PC.
The most common way to share a USB printer between two PCs is to use one machine as a print server. However, that’s not always convenient because it means that the server PC must always be on if you want to print something.
Picture of the project:
That can be a real nuisance if you just want to quickly fire up the other machine and print something out. It also means that the two PCs must be networked together, either via a hub/router or directly via an ethernet crossover cable. Another way is to use a dedicated USB print server. However, as before, this must be connected to an ethernet network, along with the PCs. Such devices also need their own power supply, generally cost well over $100 and are overkill if you just want to share a single USB printer between two computers for occasional printing in a home set-up.
Parts layout:
That’s where this simple device comes in. It’s basically a 2-way switch box that lets you manually switch your USB printer from one PC to the other, as required. The switching is performed using a rotary switch, while two LEDs on the front panel indicate which PC has been connected to the printer. This method has several advantages. First, you don’t need to network your two computers. Second, you can print from either machine with the other turned off. And third, the device doesn’t need a power supply.
Circuit diagram:
The circuit uses switch poles S1a-S1c to select either USB socket CON1 or CON2 and connect its pins through to CON3. The fourth pole (S1d) selects either LED1 or LED2, to indicate which PC has been selected.
Source: Silicon Chip14 April 2009
Thursday, March 21, 2013
Automatic TV Lighting Switch
The author is the happy owner of a television set with built-in Ambilight lighting in the living room. Unfortunately, the television set in the bedroom lacks this feature. To make up for this, the author attached a small lamp to the wall to provide background lighting, This makes watching television a good deal more enjoyable, but it ’s not the ideal solution. Although the TV set can be switched off with the remote control, you still have to get out of bed to switch off the lamp.
Circuit diagram :
Automatic TV Lighting Switch Circuit Diagram
Consequently, the author devised this automatic lighting switch that switches the background light on and off along with the T V set. The entire circuit is fitted in series with the mains cable of the TV set, so there’s no need to tinker with the set. It works as follows: R1 senses the current drawn by the TV set. It has a maximum value of 50 mA in standby mode, rising to around 500 m A when the set is operating. The voltage across R1 is limited by D5 during negative half- cycles and by D1– D4 during positive half-cycles. T he voltage across these four diodes charges capacitor C1 via D6 during positive half-cycles. This voltage drives the internal LED of solid-state switch TRI1 via R2, which causes the internal triac to conduct and pass the mains voltage to the lamp. Diode D7 is not absolutely necessary, but it is recommended because the LED in the solid-state switch is not especially robust and cannot handle reverse polarisation. Fuse F1 protects the solid-state switch against overloads. T he value of use d here (10 Ω) for resistor R1 works nicely with an 82-cm (32 inch) LCD screen.
With smaller sets having lower power consumption, the value of R1 can be increased to 22 or 33 Ω, in which case you should use a 3-watt type. Avoid using an excessively high resistance, as otherwise TRI1 will switch on when the TV set is in standby mode. Some TV sets have a half-wave rectifier in the power supply, which places an unbalanced load on the AC power outlet. If the set only draws current on negative half-cycles, the cir-cuit won’t work properly. In countries with reversible AC power plugs you can correct the problem by simply reversing the plug. Compared with normal triacs, optically cou-pled solid-state relays have poor resistance to high switch-on currents (inrush currents).
For this reason, you should be careful with older-model TV sets with picture tubes (due to demagnetisation circuits). If the relay fails, it usually fails shorted, with the result that the TV background light remains on all the time. If you build this circuit on a piece of perf-board, you must remove all the copper next to conductors and components carrying mains voltage. Use PCB terminal blocks with a spacing of 7.5 mm. This way the separation between the connections on the solder side will also be 3 mm. If you fit the entire arrangement as a Class II device, all parts of the circuit at mains potential must have a separation of at least 6 mm from any metal enclosure or electrically conductive exterior parts that can be touched.
http://streampowers.blogspot.com/2012/06/automatic-tv-lighting-switch_11.html
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