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The improvement of 555 Great Wall floor fan electronic selec

2014-11-01 09:01  
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The improvement of 555 Great Wall floor fan electronic selection time circuit
The great wall FS7-40 floor fan adopts the general mechanical electromagnetic relay,as a result,when we are shifting,it's always being the mechanical metal contact's contacting and opening which produces the mechanical noise and discharge spark. Using solid relay and connecting control circuit which consists of 555 can solve this problem. The figure 12-16 is an improved selection time circuit.The solid relay adopts sp1110-2.Its input voltage is between 2vand 6v,and the input current is between 10mAand 50mA,the on state current is 3A. To avoid the influence of the power voltage's change on the triggering and turn-on,we should use w7805 or w7806 to stabilize the +12V original power voltage. Through changing the vibration period and the Duty ratio can Change the RP1 and RP2. The R3 is the relay's limiting current.The D3 is used for the relay's over voltage protection.The R4 and C2 is used for absorpting the surge current to increase the safety.