The siren light uses that general use motor help in the whirl lamp or refect go to around, which weigh very and when be usable go to for a long time will cause the wearing out. but if we modify light running pretend siren make get siren that weighs light and can be usable for a long time go up.
How it works
The work of the circuit will divide the work goes out to are 3 the part, be origin frequency part will compose IC1 555 numbers will perform frequency origin. Which fix get with the value of R1, R2 and C1. By send signal the frequency goes out pin 3 ways s of IC1 second part is the part of counter circuit. Which compose IC2 number CD4017. Which build the circuit counts 4 the order.
There is the order volt output at 3, 2, 4 pin and 7 respectively whirl to go to continually. Which the speed in the measurement is will under frequency signal at 14 pin of IC2 and in third part be lamp driver circuit.
Which compose Q1-Q4 and R3-R6 by have the principle works to are when have voltage level at pin 3 of IC2 have current flow through R3 reach pin B of Q1 make Q1 bias cause L1 and L2 stick bright in case same of at pin 2, 4 and 7. When have voltage level as a result make transistor work by Q1-Q4 will work respectively of a signal from pin 3, 2, 4 and 7 which make lamp bright in order.
If you want to see more Siren circuits please see them.
+ Most common emergency sirens circuits
+ Police bicycle siren circuits
+ Electronic siren circuit with two transistor
+ High power siren circuit using CD40106
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