It is a Easy make Electronic Circuit Project of Fiber optic led driver Circuit. 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 during the less difficult turn-on transition.

Fiber Optic LED Driver Circuit Diagram:


This asymmetric current handling capability of the output stage with its variable impedance substantially reduces the pulse-width distortion and long-tailed response. As the signal propagates through two NAND gates, each transition passes through the high-to-low and low-to-high transition once, normalizing the total propagation delay through the circuit.

This 6 channel LED driver circuit is designed using MCP34845 ic manufactured by Frescale Semiconductor with integrated power supply. The MCP34845 6 channel LED driver circuit operates from 5 to 21 volts and is specially designed for use in backlighting LCD displays from 10” to 17”+ for devices like: PC Notebooks, Netbooks, Picture Frames, Portable DVD Players , Small Screen Televisions , Industrial Displays, Medical Displays, etc.

6 Channel LED Driver Circuit Diagram:


The MCP34845 LED driver is capable of driving up to 16 LEDs in series in 6 separate strings. PWM dimming is performed by applying a PWM input signal to the PWM pin which modulates the LED channels directly.

Main features of this driver electronic project are : input voltage of 5.0 to 21 V , boost output voltage up to 60 V, 2.0 A integrated boost FET , fixed boost frequency - 600 kHz or 1.2 MHz , OTP, OCP, UVLO fault detection , LED short/open protection , programmable LED current between 3.0 mA and 30 mA.

This is a very simple Electronic Circuit Project for LED Circuit Project Using with 555 IC. This circuit LED reproduces the first LED sequence at this time used by FISA on behalf of Formula single racing. It may perhaps be alive used with slot car sets (such for example HO shin up AFX/Life Like/Tyco sets) or else means of communication controlled cars. IC1, a 555 timer IC, is used as a watch pulse generator. Its output is fed via NAND gates IC2a and IC2c to IC3, a 4024 binary counter. IC2b inverts the O4 output of 4024 binary counter IC3. originally, IC3 is reset and all its outputs are low, together with O4, which causes IC2b to present-day a rational climax to the pin 8 input of IC2c which after that passes pulses from the 555 timer circuit to the clock input of the 4024. IC3 then begins together with.

LED Circuit Project Using with 555 IC:



Following the count has reached binary 1111, the subsequently pulse sends the O4 output of IC3 high, which disables IC2c and IC3 stops with. The four used outputs of IC3 are connected to a resistor ‘ladder’ which acts to the same degree a clear-cut digital to analog convert-er (DAC). As the count increases so does the voltage produced by the side of the top of the ladder and this is connected to the inverting inputs of four comparators inside IC4 (an LM339) and to IC5, which is a 741 op amp furthermore connected while a comparator.

The categorical inputs of the comparators are connected to the taps of a voltage dividing wall, with the drumming voltages settle on using VR1, a 100kO trimpot. As IC3 counts, the rising stepped voltage from the DAC ladder switches the comparators on clothed in sequence, preliminary with IC4d and working up to IC5. in the same way as both comparator is curved on, its pair off of LEDs is lit; former LEDs 1 & 2, next LEDs 3 & 4 and so on. as soon as all five pairs of LEDs are lit, the then pulse from IC1 moves the binary count of IC3 to 10000, so the DAC voltage drops back to zilch and all LEDs are extinguished. by the same spell, with too stops, for the reason that the area of high pressure on O4 causes IC2c to check extra gate pulses. The circuit in that case remains reserve until the counter is reset by urgent pushbutton switch S1. This allows a recent sequence to initiate.


source By:w3circuits
 

Light emitting diodes are advantageous due to their smaller size, low current consumption and catchy colours they emit. Here is a running message display circuit wherein the letters formed by LED arrangement light up progressively. Once all the letters of the message have been lit up, the circuit gets reset. The circuit is built around Johnson decade counter CD4017BC (IC2). One of the IC CD4017BE’s features is its provision of ten fully decoded outputs, making the IC ideal for use in a whole range of sequencing operations.In the circuit only one of the outputs remains high and the other outputs switch to high state successively on the arrival of each clock pulse.

Running Message Display Circuit Diagram:



The timer NE555 (IC1) is wired as a 1Hz astable multivibrator which clocks the IC2 for sequencing operations. On reset, output pin 3 goes high and drives transistor T7 to ‘on’ state. The output of transistor T7 is connected to letter ‘W’ of the LED word array (all LEDs of letter array are connected in parallel) and thus letter ‘W’ is illuminated. On arrival of first clock pulse, pin 3 goes low and pin 2 goes high. Transistor T6 conducts and letter ‘E’ lights up. The preceding letter ‘W’ also remains lighted because of forward biasing of transistor T7 via diode D21. In a similar fashion, on the arrival of each successive pulse, the other letters of the display are also illuminated and finally the complete word becomes visible. On the following clock pulse, pin 6 goes to logic 1 and resets the circuit, and the sequence repeats itself. The frequency of sequencing operations is controlled with the help of potmeter VR1.

The display can be fixed on a veroboard of suitable size and connected to ground of a common supply (of 6V to 9V) while the anodes of LEDs are to be connected to emitters of transistors T1 through T7 as shown in the circuit. The above circuit is very versatile and can be wired with a large number of LEDs to make an LED fashion jewellery of any design. With two circuits connected in a similar fashion, multiplexing of LEDs can be done to give a moving display effect.

This proximity detector circuit is designed using a temperature sensor and TLC272 op amp. The temperature sensor can react to any heat generated by body heat.

Proximity Detector Using TLC272 Circuit Diagram:



The sensor used in this TLC272 proximity detector circuit has a sensitive surface which was divided in two, so that it can sense if the heat source is coming from the left or right. Indication for cold objects will be exactly opposite of the warm objects. IC1b form a symmetrical power circuit. Terminal "s" is the sensor output. Signal over the "s" will be amplified in IC1a, with a gain factor of 70, before being delivered to the output detector.