Mutchus

This is a circuit for emergency lighting with LEDs that uses electricity from the telephone line . Generally the phone line has a DC voltage 48V and somewhere around 20 mA , and when the phone rings , the voltage rises to 96V AC . This works in a way that the phone line will not be busy while the LEDs are turned on and when you pick up the phone , the light goes off and lets you use your phone normally .  Emergency Light using Phone Line Circuit Diagram

This circuit may be used for transforming music into dancing light patterns. The operation of the circuit is very simple, the music input is fed to the bases of the shown transistor array, each of them are configured to conduct at a specific voltage level in the incrementing order from the top to the bottom transistor. Thus the uppermost transistor conducts with the input music is at the minimum volume level and the subsequent transistor starts to conduct in sequence as per the volume or the pitch of the music. Each transistor is rigged with individual lamps which light up in response to the music levels in a “chasing” dancing light pattern. Parts List All the base presets are = 10K, All the collector resistors are 470 Ohms, All the diodes are = 1N4148, All NPN transistors are = BC547, The single PNP transistor is = BC557, All the triacs are = BT136, The input capacitor = 0.22uF/25V non polar.

T his  automatic  bicycle  light  makes cycling in the dark much  easier (although you still need  to pedal of course). The circuit  takes  the  ambient  light  level  into account and only turns on  the light when it becomes dark.  The light is turned off when no  cycling has taken place for over  a minute or if it becomes light  again. The biggest advantage of  this circuit is that it has no manual controls. This way you can  never ‘forget’ to turn the light  on or off. This makes it ideal for  children and those of a forgetful  disposition. Bicycle Light Image : To detect when the bicycle is  used (in other words, when the  wheels turn), the circuit uses a  reed switch (S1), mounted on  the frame close to the wheel.  A small magnet is fixed to the  spokes (similar to that used with  most  bicycle  speedometers),  which  ...

This is a very basic circuit for flashing one or more LEDS and also to alternately flash one or more LEDs.It uses a 555 timer setup as an astable multivibrator with a variable frequency.With the preset at its max. the flashing rate of the LED is about 1/2 a second. It can be increased by increasing the value of the capacitor from 10uF to a higher value.  For example if it is increased to 22uF the flashing rate becomes 1 second. There is also provision to convert it into an alternating flasher. You just have to connect a LED and a 330ohm as shown in Fig.2 to the points X and Y of Fig.1. Then both the LEDs flash alternately.Since the 555 can supply or sink in upto 200mA of current, you can connect upto about 18 LEDS in parallel both for the flasher and alternating flasher (that makes a total of 36 LEDs for alternating flasher).  Light Flasher Circuit Diagram

This white-LED driver circuit is ideal for use in a garden light. It automatically turns the LED on at night and runs from a single 1.2V nicad cell which is recharged by a solar cell during the day. The prototype used the existing casing and solar cell from an old garden light but you could also use a solar cell from a solar education kit. Diode D1 allows the solar cell to charge the battery during the day and prevents it from discharging back into the solar cell at night. Transistor Q1 controls the LED driver circuit. This transistor is normally on during the day (ie, when there is output from the solar cell) and so Q2 and the LED are off. At night time, Q1 is off and this allows a simple blocking oscillator circuit based on T1, R2 and Q2 to operate. This circuit in turn drives LED1 via a 1W resistor which limits the peak current into the LED. T1 is wound bifilar, with the two windings configured to produce a center-tapped winding. Winding AB is the main primary winding and winding BC...

In essence, this circuit is a 15 to 20-second courtesy light extender for cars. It is activated in the usual way by opening a door but it also samples the negative lock/unlock signals from a car alarm or central locking and does two more things. First, when an unlock signal is received, it turns on the courtesy light for 15-20 seconds before you open the door. Second, when a lock signal is received, it turns off the courtesy light immediately, with no fade-out. This is done to eliminate false triggering of the burglar alarm through current drain sensing. When a car door is open or the unlock relay is activated, the 33µF capacitor discharges through diode D1 and this keeps transistor Q1 turned off. Circuit diagram: Courtesy Light Extender Circuit Diagram This allows Q2 and Q3 to turn on and the courtesy lamp is activated. When the door is closed, the courtesy lamps stay illuminated and the 33µF electrolytic capacitor starts charging through the associated 1MO resistor. As the voltages ...

Joe Collier and Kai Wei Tang created a concept cell phone Light Phone size of a credit card, which is connected to the main cell phone and has only the function calls. 

The circuit detects a sudden shadow falling on the light-sensor and sounds the bleeper when this happens. The circuit will not respond to gradual changes in brightness to avoid false alarms. The bleeper sounds for only a short time to prevent the battery running flat. Normal lighting can be used, but the circuit will work best if a beam of light is arranged to fall on the light-sensor. Breaking this beam will then cause the bleeper to sound. The light sensor is an LDR (light-dependant resistor), this has a low resistance in bright light and a high resistance in dim light. Simple Light Sensitive Alarm Circuit Diagram The light-sensitivity of the circuit can be adjusted by varying the 100k preset. The length of bleep can be varied from 0.5 to 10 seconds using the 1M preset. Using the 7555 low-power timer ensures that the circuit draws very little current (about 0.5mA) except for the short times when the bleeper is sounding (this uses about 7mA). If the circuit is switched on contin...

Introduction I created this circuit in an attempt to make the simplest possible solar powered project. It would make for an excellent science fair project, and would also serve as a good introduction to solar powered circuitry. It may also have some practical uses, such as shedding some light into a dark part of your house. The idea is simple, the solar panel converts sunlight into a trickle of electricity. The electricity is used to run a white LED. Specifications Operating Voltage: 3.7V DC Solar Current: 25ma max. LED Lamp Operating Current: 10-25ma. Theory The remote solar powered LED light takes advantage of the current limited nature of solar photovoltaic cells. If light shines on the solar array, current will flow through the circuit. For a typical size of solar cell, there is a maximum current that can be produced. The maximum solar cell current is simply matched to a value of current that the LED can handle. If there is enough light to raise the solar panel's voltage ab...

This is a very basic circuit for flashing one or more LEDS and also to alternately flash one or more LEDs.It uses a 555 timer setup as an astable multivibrator with a variable frequency.With the preset at its max. the flashing rate of the LED is about 1/2 a second. It can be increased by increasing the value of the capacitor from 10uF to a higher value.  For example if it is increased to 22uF the flashing rate becomes 1 second. There is also provision to convert it into an alternating flasher. You just have to connect a LED and a 330ohm as shown in Fig.2 to the points X and Y of Fig.1. Then both the LEDs flash alternately.Since the 555 can supply or sink in upto 200mA of current, you can connect upto about 18 LEDS in parallel both for the flasher and alternating flasher (that makes a total of 36 LEDs for alternating flasher).  Light Flasher Circuit Diagram

Description  This circuit is designed on request and can be useful to those whishing to have, say, a red LED illuminated when an appliance is on and a green LED illuminated when the same appliance is off. Any mains operated appliance can be monitored by this circuit provided a suitable mains switch, capable of withstanding the full load current, is used for SW1.When SW1 is closed, the load and D4 are energized, Q1 is saturated and shorts D3, thus preventing its illumination. Circuit Diagram: Parts: R1 = 27K-1W R2 = 27K-1W R3 = 6.8K D1 = 1N4007 D2 = 1N4007 D3 = Green D4 = Red Led Q1 = BC337 SW1 = SPST Mains Switch Notes: Change R1 and R2 to 15K 1W for 115Vac mains operation. SW1 must be capable of withstanding the appliance's full load current and volage Source- http://www.redcircuits.com/#home

Very often when enjoying music or watching TV at high audio level, we may not be able to hear a telephone ring and thus miss an important incoming phone call. To overcome this situation, the circuit presented here can be used. The circuit would automatically light a bulb on arrival of a telephone ring and simultaneously mute the music system/TV audio for the duration the telephone handset is off-hook. Lighting of the bulb would not only indicate an incoming call but also help in locating the telephone during darkness. Circuit diagram : Telephone line Based Audio Muting and Light-On Circuit Diagram On arrival of a ring, or when the handset is off-hook, the inbuilt transistor of IC1 (opto-coupler) conducts and capacitor C1 gets charged and, in turn, transistor T1 gets forward biased. As a result, transistor T1 conducts, causing energisation of relays RL1, RL2, and RL3. Diode D1 connected in antiparallel to inbuilt diode of IC1, in shunt with resistor R1, provides an easy path for AC cu...

Light Emitting Diode The LESD is basically a device which changes input electrical energy into output optical radiation in the visible or infrared position of spectrum depending on the semiconductor material used. LEDs have replaced incandesced lamp in many applications because of low voltage long life and fast on off switching. He materials used in manufacturing the LEDs are 1.        Gallium Arsenide Phosphide (GaAsP): It provides either red light or yellow light. 2.        Gallium Phosphide (GaP): It provides red or green light. 3.        Gallium Arsenide (GaAs): It provides infrared radiation Principle: When a P-N junction forward biased, charge carrier recombination take place at a junction as electron cross from the n- side and combine with holes on the p- side. Free electrons are in the conduction band of energy level while holes are in the valence band. Therefore electronics are at place ...

The above circuit is a light sensitive automatic switch which functions in the absence of light. We are using IC 4060 in this circuit which works as an oscillator and the generated signal is applied to the base of T4 transistor.Phototransistor T3 is in conduction by existence of light and it keeps the T5 transistor’s base at ground potential. When no light reaches the phototransistor, it gets in insulation. T3 reaches positive potential through 22kohm. T4 and T5 both gets in conductance. The oscillator signal reaches the optic coupler and lamp(s) shines.