Led circuits

The device comprises two parts: LED control board and LED display board. The two PCBs are designed to fit together one behind the other using two sets of dual row connectors and 4 spacers. One of this connector is used for the electrical connections, while the other is only used as a mechanical connecting element. The core of the device is microcontroller PIC18F252 (U9). It controls all the functions of the device, generates the overall algorithm to control the LED matrix......

This circuit operates a LED in pulsing mode, i.e. the LED goes from off state, lights up gradually, then dims gradually, etc. This operation mode is obtained by a triangular wave generator formed by two op-amps contained in a very cheap 8 pin DIL case IC. Q1 ensures current buffering, in order to obtain a better load drive. R4 & C1 are the timing components: using the values shown in the parts list, the total period is about 4 seconds...

We hold the "first rights" to the presentation of this approach and the best part is: "It's FREE!" The PIC12C508A is one of the most amazing devices but because it does not come in a low-cost re-programmable form, it has never been presented in a "designers article." It is a one-time programmable device (OTP) and once it is programmed, it cannot be re-programmed. To develop with this chip is not an economical decision as it may take 30 to 100 modifications before you.....

This circuit uses a set of 13 differently colored LEDs to generate a full color spectrum. The photo does not fully represent the colors generated due to camera limitations. The real-world display is very eye-catching. If you want to "trick out" your PC, this circuit is for you. Forget about those boring blue PC light displays...

Views: 2303 | Votes: 108 | Comments: 0 | Rating: 1 | Rank: 6 | Added: Feb 19, 2013 |

This neat little circuit provides 8 LEDs directly driven from the PIC along with a single mode control switch. The firmware elsewhere on this page drives the LEDs with a 5 bit PWM signal providing each of the 8 LED channels with four levels of intensity; off, dim, mid, bright. A number of sequences are programmed into the firmware to provide some interesting visual effects and chase sequences, including the classic effect seen on the car in the Knight Rider TV series. ..

This indicator lets you see how much power an amplifier produces. The circuit uses an LM 3915, the logarithmic variation of the known IC LED VU Meter LM 3914. The circuit is connected directly to the speaker output of amplifier power and can indicate 0.2 watts to 100 watts. The sensitivity of the circuit can be varied by R1. The basic settings in the table...

This is a programmable clock timer circuit that uses individual LEDs to indicate hours and minutes. 12 LEDs can be arranged in a circle to represent the 12 hours of a clock face and an additional 12 LEDs can be arranged in an outer circle to indicate 5 minute intervals within the hour. 4 additional LEDs are used to indicate 1 to 4 minutes of time within each 5 minute interval. ..

This indicator shows through a dual-LED see if a fuse is intact. The module is designed for 230 V AC. The green LED illuminates when the fuse is still good, the red lights when the fuse is broken. Perhaps the circuit to adjust for other voltages by changing the value of R1...

To add tones or shades of the main colors to the tricolor LED, you do not need to modify the circuit in Figure 1; you need only consider the software. Software modifications consist of adding more color planes or pages of display buffer, adding memory locations (mapped onto the LED dots), and increasing the number of refresh times, in which the controller updates all LED dots to cover all added color planes. For example, if you decide to use four color planes, divided.....

By removing the LEDx_ON jumpers, LM27961 output currents can easily be measured. Removing the jumpers disconnects the anodes (DxA) and cathodes (DxB) of all LEDs from POUT (DxA) or GND (DxB), breaking the LED current paths. By placing a current meter between the two header pins the sum total of all LED currents can be measured. With the LEDx_ON jumpers removed, the current of an individual output can be measured by placing a current meter between a DxA header and.....

This simple and inexpensive circuit built around a popular CMOS hex inverter IC CD4069UB offers four sequential switching outputs that may be used to control 200 LEDs (50 LEDs per channel), driven directly from mains supply. Input supply of 230V AC is rectified by the bridge rectifiers D1 to D4. After fullwave rectification, the average output voltage of about 6 volts is obtained across the filter comprising capacitor C1 and resistor R5. This supply energises IC CD4069UB...

This circuit is same as the above setup to drive 25 small Xmas lights. The lights operate at about 200mA and 3 volts. The supply voltage is set to 5 volts and the 4017 counter output will drop about a volt using the 2N3053 transistors. The voltage on the emitters of the rows transistors will be about 0.7 volts less than the base so the lamp voltage will be about 3 volts. You can adjust the supply voltage for the desired current if necessary. It works the same way as the.....

This is the most simple phone busy indicator is possible with only three parts. Connect the circuit so that the green light illuminates when the line is free. If the receiver than the hook, the green LED light is weak. When connecting the red LED. ..

The 555 timer IC is connected for Astable Operation, the clock pulses are fed to the 4017 IC via the 10K resistor. The 4017 is a 10 stage counter, each of the outputs is connected to the appropriate LED, as some LEDs need to be on for more than one count, we use diodes to avoid a short circuit situation between outputs. The capacitor and resistor on pin 15 of the 4017 are used to reset the counter to zero at initial power up. The ULN2001N used on the bulb version is a.....

This is basically a flasher circuit modified to turn on and off a bulb instead of a LED. It uses a 555 timer IC working as an astable multivibrator. The flashing rate can be varied from very fast to a maximum of once in 1.5 sec by varying the preset VR1...

In the early `80s, I read some articles on LED arrays. They described using arrays of 64 or more LEDs as crude oscilloscopes and other interesting things. I decided I`d make one myself - a really big array, 256 LEDs arranged as 16 columns by 16 rows. In 1983, while I was in my final semester of electronics classes at Monterey Peninsula College, I designed my array. I wanted a high-density array, in part to make the PC board smaller, but mainly to give a better appearance......

Views: 4645 | Votes: 99 | Comments: 0 | Rating: 3 | Rank: 7 | Added: Feb 14, 2013 |

The LM3485 LED driver board is a buck regulator derived controlled current source designed to drive high power, high brightness LEDs (HBLEDs) such as the Luxeon¾ Emitter at dissipations of 1W to 5W. The board can accept an input voltage ranging from 5V to 30V and can control the output current delivered to series and/or parallel arrays of HBLEDs as long as the forward voltage of all LEDs in series is less than (0.9 x VIN). The accuracy of the output current is ±10%...

The LED flasher circuits below operate on a single 1.5 volt battery. The circuit on the upper right uses the popular LM3909 LED flasher IC and requires only a timing capacitor and LED. The top left circuit, designed by Andre De-Guerin illustrates using a 100uF capacitor to double the battery voltage to obtain 3 volts for the LED. Two sections of a 74HC04 hex inverter are used as a squarewave oscillator that establishes the flash rate while a third section is used as a.....

The basic circuit illuminates up to ten LEDs in sequence, following the rhythm of music or speech picked-up by a small microphone. The expanded version can drive up to ten strips, formed by up to five LEDs each, at 9V supply. IC1A amplifies about 100 times the audio signal picked-up by the microphone and drives IC1B acting as peak-voltage detector. Its output peaks are synchronous with the peaks of the input signal and clock IC2, a ring decade counter capable of driving up.....

If we have a lot of parallel telephones on a telephone line, we needed a unit that will have the possibility of showing if somebody of the telephone has raised the earphone. Our this possibility give the circuit. The circuit is connected at parallel with the two cables of telephone line. The bridge of rectification D1- D4, protect and ensure the circuit from error polarity connection. If no telephone is not raised, then voltage in telephone is 50V until 70V roughly. This.....