Anyone who has designed circuits using the 555 timer chip will, at some time have wished that it could be programmed for longer timing periods. Timing periods greater than a few minutes are... Read more
The circuit described here is a testament to the ingenuity of two young designers from a specialist technical secondary school. The ‘garage timer’ began as a school electronics project and h... Read more
This circuit is innovative in more than one way and therefore belongs per se in Elektor’s Small Circuits Collection. Firstly, it demonstrates how the combination of a blue and a white LED ca... Read more
Most darkness activated alarms employ opamps and some logic ICs. Here, a less expensive approach is shown based on the eternal 555, this time in monostable multivibrator mode. Components R2... Read more
It features at least once in every Small Circuits collection: the 555 timer. In this simple circuit we give the chip a little more attention than usual (refer to ‘The Eternal 555’ in the Jul... Read more
This LED blinker manages with only a few components and is dimensioned to operate from an ac supply in the range of 4–16 V (6–24 V dc). As its current consumption is less than 1 mA, it’s als... Read more
This energy saving, a 12-V controller is nearly universally applicable. In addition to controlling battery powered lighting in a car, boat or caravan it is also quite able to control the spe... Read more
This infrared alarm can be used to detect persons passing through doorways, corridors, and small gates. The transmitter emits a beam of infrared light which is invisible to the human eye. Th... Read more
This is a tried and trusted design for the protection against overvoltages that can be configured for your own needs. The circuit can also be used to detect under voltages; in that case, the... Read more
This circuit is designed to help minimise the quiescent power consumption of PCs and notebooks, using just our old friend the 555 timer and a relay as the main components. The circuit itself... Read more
