Ramsey Electronics PG13 Manuál s instrukcemi stáhnout pdf (Strana 4)

ECS1• 4

INTRODUCTION

Everyone has heard the crickets outside their window peep, peep, peeping,

but some people don’t know that those chirps can be used to measure

temperature! If you count the number of chirps in 15 seconds and add 40,

you have roughly the Fahrenheit temperature. Isn’t that swell? The ECS1 is

an electronic version of those little temperature telling crickets. It will chirp to

temperature just like them. So all you do is build it, tweak it, then: peep, peep

peep, “Hey it’s 72 degrees out”.

ECS1 CIRCUIT DESCRIPTION

Well for all of you who haven’t seen enough of the uber-classsic LM555 timer

IC, this circuit is for you. If by some chance there is someone who has not

used one before, this kit will indoctrinate you into the “in” crowd and you will

now be cool. There be three timers: U1, U2, and U3. They have teamed up

to create the sound of the cricket. Before you understand the electronics you

must understand the cricket chirp. I, the kit designer, have spent much time

learning about this so that my kit will sound right. So, now you, the kit builder,

shall be enlightened. A cricket chirp is composed of a group of three

amplitude modulated sine waves occurring in rapid succession. Observe the

picture. Each group of three is one chirp. This picture is an actual output from

a wave file of recorded cricket sound. When it is played the result is: “chirp

chirp chirp”. If you zoom way in on one chirp it looks like the next picture.

As you can see, it is made up of a sine wave of a single frequency (about

5KHz) that ramps up and then back down again. This is the essence of the

cricket chirp. The ECS1 is meant to reproduce this closely enough that it

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Ramsey Electronics PG13 Manuál s instrukcemi Strana 4