Led circuits

Inserting two 1-MO resistors, R1 and R2, in the output stage of one of the circuit"s inverters limits the current needed by the oscillator tone more than a few pA. This circuit includes a CD4007 package, which has three CMOS inverters. It forms a standard three-inverter oscillator. Resistors R1 and R2, in series with separate drains on inverter pins 8 and 13, limit the oscillator"s supply current. Capacitor C1 and resistors R5 set the off time of the oscillator, C1; R6.....

Views: 35 | Votes: 68 | Comments: 0 | Rating: 9 | Rank: 5 | Added: Mar 27, 2013 |

Have you ever wondered how many different colors can illuminate a LED? One, two or maybe three? Constructing this simple circuit, you will find it much more. The key component in this design is a dual LED. One such accessory includes two inside the 'slices' of different diode LED, that each of them produces a different color (usually green and red). For the drive requires three pins, a common cathode and two separate roots. In this way each of the two integrated diodes can.....

Views: 1058 | Votes: 19 | Comments: 0 | Rating: 8 | Rank: 5 | Added: Mar 19, 2013 |

The flash rate is determined by CI and R4. ..

Views: 3262 | Votes: 78 | Comments: 0 | Rating: 1 | Rank: 4 | Added: Mar 16, 2013 |

The circuit will modulate the light from the LED using a crystal microphone or a loudspeaker output. To obtain the maximum range, the optical system must be efficient (see example). Either a convex lens or a concave mirror can be used to convert the LED output into a parallel beam. The received light is concentrated onto a sensitive photodarlington transistor. ..

Views: 5072 | Votes: 19 | Comments: 0 | Rating: 8 | Rank: 6 | Added: Feb 27, 2013 |

The pull-up transistor of the totem-pole output is used-to turn on the LED and the pull-down transistor is used to turn ·off the LED. The lower impedance and higher current handling capability of the saturated pull-down transistor is used as an effective method of transferring the charge from the LED"s anode to ground as its dynamic resistance increases during turn-off. The slightly higher output impedance of the pull-up stage ensures that the LED is not over peaked.....

Views: 8 | Votes: 63 | Comments: 0 | Rating: 9 | Rank: 5 | Added: Jan 22, 2013 |

Uses a low cost CMOS IC to tum four LEDs on and off at a rate that is set by the values of R1, R2, Cl, and C2. The pulse rate for the component values given for R1 and R2 is about one cycle every four seconds. By lowering the values of Rl and R2 to 220 KO, the pulse rate increases to 1Hz. The LEDs flash in pairs, with LEDl and LED4 turning together for one half of the time period, while LED2 andLED3 are on for the other half. ..

Views: 9 | Votes: 15 | Comments: 0 | Rating: 5 | Rank: 5 | Added: Dec 6, 2012 |

A relaxation oscillator is used to flash an LED in the base circuit. Cl is charged slowly through R1 by the power source, then discharged periodically through R3 and the LED by the UJT. ..

Views: 2928 | Votes: 27 | Comments: 0 | Rating: 9 | Rank: 4 | Added: Dec 4, 2012 |

The ·circuit includes a peak detector that irrunediately drives the readout to any new higher signal level and slowly lowers it after the signal drops to zero. The readout is a moving dot or expanding bar display. The circuit can be expanded for a longer bar readout. Tapping five or more LED peakmeters into a frequency equalizer or series of audio filters should give a unique result. ..

Views: 15 | Votes: 11 | Comments: 0 | Rating: 5 | Rank: 5 | Added: Nov 3, 2012 |

Battery-operated equipment can work on one set of batteries for a long time nowadays. However, if it is left on inadvertently,..

Views: 5 | Votes: 37 | Comments: 0 | Rating: 1 | Rank: 5 | Added: Nov 1, 2012 |

A bar column of LEDs is arranged so that as the audio signal level increases, more LEDs in the column light up. The LEDs are arranged vertically in 6 dB steps. A fast response time and a one second decay time give an accurate response to transients and a low "flicker" decay characteristic. On each of the op amps inverting inputs is a dc reference voltage, which increases in 6 dB steps. All noninverting inputs are tied together and connected to the positive peak envelope of.....

Views: 5456 | Votes: 98 | Comments: 0 | Rating: 5 | Rank: 5 | Added: Oct 27, 2012 |

Indicator was designed for displaying the peak level of small ac signals from a variety of transducers including microphones, strain gauges and photodiodes. The circuit responds to input signals contained within the audio frequency spectrum, i.e., 30 Hz to 20 kHz, although a reduced response extends up to 40 kHz. Maximum sensitivity for the component values shown, with VR1 fully clockwise, is 30 mV peak-to-peak. ..

Views: 1470 | Votes: 8 | Comments: 0 | Rating: 4 | Rank: 5 | Added: Oct 24, 2012 |

Three individual flashing circuits that use an LM3909 LED flasher/oscillator IC create the appearance of a pseudo-random firing order. The combination of CX!RV C.JRb, and C^R control the blink rate, which is between 0.3 and 0.8 s, and the inherent wide tolerance range [-20% to +80%) of standard electrolytic capacitors add to the irregularities of the blink cycles. The continuous current drain is about 10 mA; however, if you decrease the values of R4 through R6 or CI.....

Views: 30 | Votes: 18 | Comments: 0 | Rating: 6 | Rank: 5 | Added: Oct 16, 2012 |

The project is designed for LED based street lights with auto intensity control using solar power from photovoltaic cells. As awareness for solar energy is increasing, more and more individuals and institutions are opting for solar energy. Photovoltaic panels are used for charging batteries by converting the sunlight into electricity. A charge controller circuit is used to control the charging. Intensity of street lights is required to be kept high during the peak.....

Views: 64 | Votes: 95 | Comments: 0 | Rating: 8 | Rank: 10 | Added: Oct 9, 2012 |

By using two switching transistors and two LEDs, this circuit can distinguish low-level ac and dc signals. If the red LED i..

Views: 11 | Votes: 83 | Comments: 0 | Rating: 0 | Rank: 5 | Added: Oct 5, 2012 |

The alternating LED flasher is simply a twotransistor oscillator witb LEDs connected to tbe collector of each transistor, ..

Views: 14 | Votes: 30 | Comments: 0 | Rating: 7 | Rank: 5 | Added: Sep 12, 2012 |

The timing components are Rl, R2, and C,. Cl is a bypass capacitor used to reduce the effects of noise. At start-up, the voltage across C, is less than the trigger level voltage (1/3 Vnn). causing the timer to be triggered via pin 2. The output of the timer at pin 3 increases, turning LEDl off, LED2 on, the discharge transistor at pin 7 off, and allowing C, to charge through resistors Rl and R2. When capacitor C, charges to the upper threshold voltage (2 /3 Vvv). the.....

Views: 13 | Votes: 71 | Comments: 0 | Rating: 3 | Rank: 5 | Added: Sep 8, 2012 |

The precision voltage-monitor chip contains a temperature-compensated voltage reference. R1 divides down the battery voltage to match the built-in reference voltage of ICl (15 volts). When the voltage at pin 3 falls below 15 volts, pin 4 supplies a constant current of 7 mA to drive a small LED..

Views: 1993 | Votes: 104 | Comments: 0 | Rating: 0 | Rank: 5 | Added: Aug 15, 2012 |

Originally intended as a 3-bell animation circuit for Christmas decorations, the circuit can be used for many other purposes that require a flasher of this kind. By re-connecting U2 (see the data manual),..

Views: 50 | Votes: 84 | Comments: 0 | Rating: 2 | Rank: 5 | Added: Aug 8, 2012 |

When power is first turned on, two of the LEDs are on and the other two remain off until the timing cycle reverses. The LEDs flash in pairs, but by pressing and holding Sl closed until only one of the LEDs is on, and then releasing it, the four LEDs can be made to flash in sequential order. The number of LEDs flashing in a sequential ring can be easily increased to eight by adding another 4001 quad NOR gate. Just repeat the circuit and connect the additional circuit in.....

Views: 13 | Votes: 70 | Comments: 0 | Rating: 0 | Rank: 5 | Added: Jul 29, 2012 |

The LED is the CSL310L which contains a red LED and a green LED connected back to back and mounted close together in a single moulding. The LED can emit red or^green light by controlling the polarity of the applied voltage and if the polarity is switched at a rate of several hundred Hertz the emitted light appears yellow. The four combinations of inputs A and can therefore be converted to four LED states—red, green, yellow and off. ..

Views: 3532 | Votes: 39 | Comments: 0 | Rating: 5 | Rank: 4 | Added: Jul 21, 2012 |