This kit wires the popular 555 IC as an astable, free-running multivibrator. In other words it is wired as a square wave oscillator. It has a double ended output connection in which one LED is OFF when the other is ON, and vice versa.
This kit wires the popular 555 IC as an
astable, free-running multivibrator. In other words it is
wired as a square wave oscillator. It has a double ended
output connection in which one LED is OFF when the other is
ON, and vice versa.
For an animation of what happens in this kit
go to
http://www.williamson-labs.com/assets/htm/480_555.htm" target=_blank
Note the animated
charging and discharging of the capacitor. Note which
resistors are involved with the charging and with the
discharging. Watch which LEDメs are on in what part of the
cycle. A few minutes watching this animation and making it go
faster will give an excellent understanding of how this
circuit works. The capacitor C2 charges exponentially through
resistors R1, R2 and the resistance of the trimpot. When C2
has charged to about 2/3 VCC
it stops charging
and it discharges to about 1/3 VCC
through R2 and
the trimpot resistance via pin 7. There are links on this site
to download the 555 Data Sheet
and a lot of other relevant information.
For another excellent website devoted to the
555 see
you can enter values for R1, R2 and C and see
what flash rates they would give.
Assembly.
It is best to add the lowest height components ヨ the
resistors ヨ first. Read the color code to make sure they are
the right ones in the right places. The ecap and the LEDs must
be put in the right way around. The two pins make it easy to
attach alligator clips to the board. You do not have to use
them if you do not want to. Finally, connect a battery or
power supply between 5V and 15V DC to the pins. The LEDs
should start to flash off and on.
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