How Police Sirens Can Be Useful?

MAJOR M MAJORPOLICESUPPLY HOW POLICE SIRENS CAN BE USEFUL? GREEK MYTHOLOGY The word siren first originated in Greek mythology, was used to III According to Greek mythology, listening to a siren could have disastrous consequences. refer to mermaids and was often associated wi dangerous temptations. EARLY MODELS In the early 19th century the very first sirens were made of pneumatic tubes and two disks. HOW IT WORKS: A sound was made when air One disk was perforated flowed from the tube to the and one disk rotated. fixed disk and caused the other disk to rotate. BASIC TYPES OF SIREN MECHANICAL SIRENS PARTS: At the bottom of a Outside of this fan is metal mechanical siren, there 4 is an electric motor that is connected to a fan. At the top of the siren is a large cone, there to take in any air that's nearby. drum with holes cut out of it on the sides in two distinct alternating rows. HOW IT WORKS: When the The motor is The movement of the mechanical police siren is turned on, fan starts sucking air in through the air intake cone. connected to a fan or rotor, which the motor starts. starts to move. When the air enters the drum Because the fan is with fan, it is then expelled out the sides through the moving at high speeds (some in excess of 7000 rpm), the air is pushed out through the hole quickly, and this causes small holes in the drum. This vibration creates the metal to vibrate the familiar loud quickly and strongly. siren sound. ELECTRONIC SIRENS PARTS: Speaker Sound modulators Oscillators Power source HOW IT WORKS: It utilize the electronic It is usually programmed to parts to produce the desired sound. make a sound that are similar to mechanical siren. EUROPEAN MODEL Some countries in Europe have developed an in-between type of police siren known as the electro-mechanic siren. HOW IT WORKS: allult. The air compressor switches It uses two air horn between both sets of horns sets with both low and so the sound alters between a high pitches. high and low pitch. It use less power than mechanical siren. RUMBLER The Rumbler® is a Rumbler is an intersection traffic clearing system that interacts with most 100/200-watt siren amplifiers to provide secondary, low frequency tones. Low frequency tones have the distinct advantage of penetrating solid materials enabling vehicle operators and nearby pedestrians revolutionary new concept to audible warning. to feel the sound waves. Sources: http://www.ehow.co.uk/info_8586793_history-police-siren.html http://www.ehow.com/how-does_4968897_police-siren-work.html http://www.fedsig.com/products/253/rumbler POLICE & FIRE SUPPLY f https://www.facebook.com/majorpolicesupp in https://www.linkedin.com/company/major-police-supply y https://twitter.com/MajorPoliceSupp wWW.MAJORPOLICESUPPLY.COM