Understanding IC 555. Design note 3

We all used IC 555 in many applications. Why it is called as 555 Timer? There are three 5K resistors inside the IC that makes it as versatile IC for Timer applications. IC555 was introduced in 1971by the Signetics corporation as SE555 / NE555 and was called as “IC Time Machine”. Later its CMOS version IC 7555 and Dual Timer IC 556 were introduced.

Battery Protector for Emergency Lamp

Emergency lamps do not have a facility to prevent the deep discharge of battery if the lamp remains on during day time. The fluorescent lamp filament also damages if it is glowing in low battery voltage. This causes blackening of the filament side that indicates the damaged filament. So we have to switch off the lamp in the morning and switch it on again in the evening. By adding this circuit in the emergency lamp, you can reduce the job of daily switching. This circuit offers two advantages

1. It prevents unnecessary discharge of battery during daytime
2. It charges the battery only during night. This save energy and prevents overcharging of the battery.

Battery Protector for Emergency Lamp.Utility Circuits 1

Emergency lamps do not have a facility to prevent the deep discharge of battery if the lamp remains on during day time. The fluorescent lamp filament also damages if it is glowing in low battery voltage. This causes blackening of the filament side that indicates the damaged filament. So we have to switch off the lamp in the morning and switch it on again in the evening. By adding this circuit in the emergency lamp, you can reduce the job of daily switching. This circuit offers two advantages

1. It prevents unnecessary discharge of battery during daytime
2. It charges the battery only during night. This save energy and prevents overcharging of the battery.

CD 4024 Toggle Switch- Design Trick 2

CD4024 is the CMOS Ripple- carry Binary counter / Divider IC used in Control counters, Frequency dividers, Timers and in Time delay circuits.CD 4024 is the 7-stage ripple counter with Master slave Flip-Flops. The counter advances with each negative going pulse in its input. A high going pulse in the reset pin will reset all the counters in zero state. Schmitt trigger action in the input pulse line permits unlimited rise and fall times. All the inputs and outputs are buffered.

Design Your Circuit. Part XI- Schmitt Trigger in Action

Design of the popular Timer IC 555 is so interesting and this tiny chip can be exploited in various ways to make different types of circuits. It can be a Monostable, Astable, Bistable, Toggle, Schmitt trigger etc. The Schmitt trigger action is achieved by exploiting the activities of its two internal comparators. Let us make an Automatic Porch light using the Schmitt trigger property of IC 555. It is an ideal circuit to light the premises of home even if the inmates are not there.