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Simple Universal Timer

By assemble NE555 and some electronic components become a mono stable multi vibrator, we can get a universal timer for our need (as seen on figure 1). This circuit is very simple to be realized. The lasting of timer can be adjusted by using appropriate value of R and C. The minimum value of R is about 1 k ohm, the lasting time is about R multiply by C.

This circuit is useful for auto turn off some devices like mini hi-fi system. In normal condition, switch a-b is positioned in a. When we need this circuit works, then the switch on pin-2 must be pressed then the switch a-b is changed to b. Then our device will on for a moment (depends on value of R multiply by C). If we need longer time, we can choose the R and or C bigger.

  

Figure 1. Simple universal timer circuit.

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