My Light Diagram

Description:  This circuit is used to slowly illuminate and fade a pair of red LEDs (light emitting diodes). The fading LEDs could be installed as 'eyes' in a small pumpkin or skull as a Halloween attraction, or mounted in a Christmas tree ornament. Or, they might be used as a fancy power indicator for your computer, microwave oven, stereo system, TV, or other appliance. In operation, a linear 3 volt (peak to peak) ramping waveform is generated at pin 1 of the LM1458 IC and buffered with an emitter follower transistor stage. The 22uF capacitor and 47K resistor connected to pin 2 establish the frequency which is about 0.5 Hz. You can make the rate adjustable by using a 100K potentiometer in place of the 47K resistor at pin 2. The circuit consists of two operational amplifiers (opamps), one producing a slow rising and falling voltage from about 3 volts to 6 volts, and the other (on the right) is used as a voltage comparator, the output of which supplies a alternating voltage swit...

Digital cameras are becoming more and more affordable. At the economy end of the market cameras are usually equipped with a small built-in flash unit that is ideal for close-ups and simple portraiture. The power rating of the built-in flash unit is quite low so that any subject further away than about 2 to 3 metres (maybe 4 m if you are lucky) tends to disappear into the gloom. You soon become aware of the limitations if you need to photograph a larger group of people say at a function under artificial light in a large hall or outdoors. Project image : Slave Flash With Red-Eye Delay Image The majority of these cameras are not fitted with an accessory socket so it is not possible to simply connect a second flash unit to increase the amount of light. Single lens reflex cameras also need additional lighting (e.g. fill-in flash) to reduce the harsh contrast produced by a single light source. For all these cases an additional slave flashgun is a useful addition to the equipment bag. Rat...