Download English Proceedings

期 The English Proceedings of the College of Instrumentation & Electrical Engineering, Jilin University, in the Second Half of 2013
Iac = 1.8I 0 max = 1.08 A ，make it 2A。
(6)Cooling fin：
P = [(V ) AV − V 0 ]* I 0 ， P max = 12.4W
way they feel the signal. The sensitivity of the ball
switch is the detection angle. It can start the circuit.
Choose sw-18020 and sw-420. But in fact,
sw-18020 is likely to be broken sometimes, so finally
choose sw-420. It is more safe and stable.
(7)According to the advice of LM317, make Cadj
10uF/25v，C2 is the compensation capacitor of C1. C2
is 0.1uF ceramic capacitor ,R1=240Ω ， R2 ：
720Ω~2.2k potentiometer.
2.2.3 Scheme III
1) Overall design
The diagram is showed in Figure5. Use the shaking
signal from the vibroswitch to link to delay-circuit can
provide power to the coil. Then begin to time. It can
show the magnitude of voltage when the coil on or off.
When the time is up, the coil will cut off. It needs a
single chip to control. Like ADC0804, NE555 and so
on. These chips are wildly used in toys and alarm
systems and control circuit. And the device designed is
the combine of these things and serve the cantilever
damping device.
Spring switch
Ball switch
Figure6 Switches
The
The delay
switch
circuit
Drive circuit and
produces
starts to
the load
a signal
work
Display
Figure5 The diagram of the system
2)The choice of the elements and applications in
circuit
(1) Information of SW-420
Now a lot of vibroswitches can be bought. This kind
of switch can close when it feels the shaking signal
and it is really cheap. It also has simple structure and it
is widely used in many fields. It can be seen as spring
switch and ball switch. The two kinds have important
features. They are sensitivity and directivity. The so
called sensitivity is that the different switches have a
difference. Users can choose different kinds of
switches when they want to use them in different
situations. Directivity is the forced direction. Most
products have the requirement in sensitivity but not in
directivity. So there is a need to know something about
how the users use them then decide which to choose.
The difference between the two kinds of switch is the
112
Finally choose a sw-420 .It has a potentiometer to
change the sensitivity and a LM393 to ensure is can
produce stable wave. The product produces a high
level when the shaking signal comes while it produces
a low level when it does not feel the signal.
(2) The relay drived by the audion
sw-420 has a large resistance, the driving current is
more than 10mA.If put coil directly into the coil will
cause the problem that it cannot have enough current
so that the magnetism will too weak. So it is necessary
to add a audion to drive the relay in order to produce
enough magnitude of current.
According to the theory, the current in the coil
should be two times than the base of the audion.
Choose the 1N4001(25V).