Showing posts with label activated. Show all posts
Showing posts with label activated. Show all posts
Thursday, January 9, 2014
Sound Activated Lights
This diy sound activated lights circuit turns a lamp ON for a short duration when the dog barks (or a relatively strong sound) giving an impression that the occupants have been alerted. The condenser microphone fitted in a place to monitor sound and generates AC signals, which pass through DC blocking capacitor C1 to the base of transistor BC549 (T1). Transistor T1 along with transistor T2 amplifies the sound signals and provides current pulses from the collector of T2. When sound is produced in front of the condenser mic, triac1 (BT136) fires, activates lights and the bulb (B1) glows for about two minutes.
Assemble the sound activated lights circuit on a general purpose PCB (circuit board) and enclose in a plastic cabinet. Power to the sound activated switch circuit can be derived from a 12V, 500mA step-down transformer with rectifier and smoothing capacitor. Solder the triac ensuring sufficient spacing between the pins to avoid short circuit. Fix the unit in the dog’s cage or close to the sound monitoring spot, with the lamp inside or outside as desired. Connect the microphone to the sound activated lights circuit using a short length of shielded wire. Enclose the microphone in a tube to increase its sensitivity.
Caution:
Since the sound activated lights uses 230V AC, many of its points are at AC mains voltage. It could give you lethal shock if you are not careful. So if you don’t know much about working with line voltages, do not attempt to construct this circuit. We will not be responsible for any kind of resulting loss or damage.
Friday, April 12, 2013
555 Timer Touch Activated Alarm Circuit Diagram
This is the circuit diagram of touch activated alarm gadget which still activated on load shedding.\r\n Alarm device can be activated when any person touch the “touch plate” \r\nwhich is referred to as trigger. In this circuit the most up to date part is automatic\r\n battery activator which is made with the help of a relay. So don’t upset on load \r\nshedding you alarm gadget is activated. This circuit will be used at \r\nyour residence door, locker, car or steel gate and many others.
![](\"https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVyRQZG0OAmwmp81M5uzVpOnWJUyFzuiWe-EgCAqAnp0XbfWswfESwUDVCwwPqArJph5g-SInmgiweex9jpYA3Ivbj_Tk3PO_LZVlg146QVW35S0yFKvlY9lSXV503kXwaBtxOfWolTN0S/s400/Touch+Activated+Alarm+Circuit.jpg\")
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Monday, April 8, 2013
How to Make a Light Activated Day Night Switch Circuit – Science Fair Project
This is the circuit diagram of a light activated switch based on National Semiconductors comparator IC LM 311 and a LDR. 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). 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.
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). 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.
Light Activated Switch Circuit Diagram with Parts List .
Light Activated Switch Circuit Diagram
Notes.
- 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.
- Assemble the circuit on a good quality PCB or common board.
- You can use either a 12 V battery or a well regulated & filtered 12V DC mains operated power supply.
- The pin 5&6 (Balance & Balance/Strobe ) of IC LM311 are shorted to minimize the chance of oscillations.
- The pin out of LM311 is also given together with the circuit diagram.
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