Wiring circuit

Friday, October 17, 2014

Simple Sound Activated Switch

Control by sound may be very useful, not just on a robot but also for a bit of home automation, for example a sound activated light responding to a knock on the door or a hand clap. The light will be automatically switched off after a few seconds. An alternative use is burglar protection — if someone wants to open the door or break some-thing the light will come on, suggesting that someone’s at home. The circuit can work from any 5– 12 VDC regulated power supply pro-vided a relay with the suitable coil voltage is used.

Simple Sound Activated Switch Circuit diagram :

Sound Activated Switch Circuit Diagram

When you first connect the supply voltage to the circuit, the relay will be energised because of the effect of capacitor C2. Allow a few seconds for the relay to be switched off. You can increase or decrease the ‘on’ period by changing the value of C2. A higher value results in a longer ‘on’ period, and vice versa. Do not use a value greater than 47 µF. Biasing resistor R1 determines to a large extent the microphone sensitivity. An electret microphone usually has one internal FET inside which requires a bias voltage to operate. The optimum bias level for response to sound has to be found by trial and error.

Wednesday, October 1, 2014

Light Activated Switch Circuit Using IC 555

A very useful light activated switch circuit can be made by utilising a single 555 timer with its trigger and threshold inputs connected together.
The schmitt has a very low input current (1.5uA) and can directly drive a relay taking up to 200mA of current. The circuit shows a 555 schmitt being used to energise a relay when the light level on a photoconductive cell falls below a preset value; the relay energises when the voltage on pins 2 and 5 is greater than 2/3Vcc and de-energises when the voltage falls below I/3Vcc. This gives a hysteresis of 1/3Vcc, The circuit can be used in many other similar applications where a high input impedance and low out- put impedance are required with the minimum component count.

Thursday, September 18, 2014

USB Switch Schematic Circuit

Anyone experimenting or developing USB ported peripheral hardware soon be comes irritated by the need to disconnect and connect the plug in order to reestablish communication with the PC. This process is necessary for example each time the peripheral equipment is reset or a new version of the firmware is installed. As well as tiresome it eventually leads to excessive contact wear in the USB connector. The answer is to build this electronic isolator which disconnects the peripheral device at the touch of a button. This is guaranteed to reduce any physical wear and tear and restore calm once again to the workplace.

Circuit image :
USB Switch-Image

USB Switch Schematic Circuit Image

The circuit uses a quad analogue switch type 74HC4066. Two of the switches in the package are used to isolate the data path. The remaining two are used in a classic bistable flip-flop configuration which is normally built using transistors. A power MOSFET switches the power supply current to the USB device. Capacitor C2 ensures that the flip flop always powers-up in a defined state when plugged into the USB socket (‘B’ in the diagram).

The peripheral device connected to USB socket ‘A’ will therefore always be ‘not connected’ until pushbutton S2 is pressed. This flips the bistable, turning on both analogue gates in the data lines and switching the MOSFET on. The PC now recognises the USB device. Pressing S1 disconnects the device.

Circuit diagram :
USB Switch-Circuit-daigram

USB Switch Schematic Circuit Diagram

The circuit does not sequence the connections as a physical USB connector does; the power supply connection strips are slightly longer than the two inner data carrying strips to ensure the peripheral receives power before the data signals are connected. The electronic switch does not suffer from the same contact problems as the physical connector so these measures are not required in the circuit. The simple circuit can quite easily be constructed on a small square of perforated strip-board.

The design uses the 74HC(T)4066 type analogue switch, these have better characteristics compared to the standard 4066 device. The USB switch is suitable for both low-speed (1.5 MBit/ s) and full-speed (12 MBit/s) USB ports applications but the proper ties of the analogue switches and perf-board construction will not support hi-speed (480 MBit/s) USB operation.

The IRFD9024 MOSFET can pass a current of up to 500 mA to the peripheral device with-out any problem.

Source : www.ecircuitslab.com

Monday, September 15, 2014

Control Switch for Fan and Air Conditioner

An electronic switch that can be used to switch on both the air-conditioner as well as fan of your room, one by one. The schema consists of power supply and control sections. The power supply section is built around transformer X1, bridge rectifier BR1 and filter capacitor C1. The 50Hz, 230V AC mains is stepped down by transformer X1 to deliver a secondary output of 9V, 300 mA. The transformer output is rectified by the bridge rectifier and filtered by capacitor C1.

Control Switch for Fan and Air-Conditioner Circuit Diagram

When the mains is switched on for the first time, pin 3 of IC CD4017 (IC1) goes high and relay RL1 energies to switch on the fan. When mains is briefly switched off using S1 and then switched on, the power to IC1 is maintained by the charge on capacitor C1. At the same time, there is a trigger pulse on the clock input (pin 14) of IC1, which advances the decade counter and relay RL2 energies to switch-on the air-conditioner. Both the air-conditioner and the fan will be turned off if the switch is in the ‘off’ position.

Assemble the schema on a general-purpose PCB and enclose in a suitable case. Fix the unit onto the switchboard. Use relays RL1 and RL2 with proper contact ratings. The current rating depends on the load that you are going to control.

Sunday, September 14, 2014

Build a Zero Crossing Switch Wiring diagram Schematic

This is a simple Zero Crossing Switch Circuit Diagram. The zero-crossing is important for systems which send digital data over AC diagram, such as modems, X10 home automation control systems, and Digital Command Control type systems for Lionel and other AC model trains. When switching loads with the aid of a thyristor, a large amount of RFI can be generated unless some form of zero crossing switch is used.

Zero Crossing Switch Circuit Diagram

The schema shows a simple single transistor zero crossing switch. Rl and R2 act as a potential divider. The potential at their junction is about 10% of the ac voltage. This voltage level is fed, via R3, to the transistor`s base. If the voltage at this point is above 0, the transistor will conduct, shunting any thyristor gate current to ground. When the line potential is less than about 2 V, it is possible to trigger the thyristor.

The diode Dl is to remove any negative potential that might cause reverse breakdown. If electrical power is to be switched, no electrical interference is generated if switched at an instant when there is no current a zero crossing. Early light dimmers and similar devices generated interference; later versions were designed to switch at the zero crossing.

Saturday, September 6, 2014

Simple Light Switch

This is a light switch or light activated relay schema.The relay on when LDR uncoverd and relay off when LDR covered.Adjust VR1 for light sensitive.LED will turn on at the same time with relay Link