Data Sheet
-135-
361. MOSFET
Connect points G and H with a 4-wire (4) in project #347. Press the
press switch (61) for a while and you will hear music in soft volume.
This is because the 100W resistor (41) limits the current through the
speaker (93). Release the press switch (61) and wait for a while. You
will eventually hear the music start breaking up and fading out.
The makeup of a Metal Oxide Semiconductor Field Effect Transistor
(MOSFET) is shown in the gure below. MOSFET’s operate the same as
JFET’s but the gate terminal is electrically isolated from the conductive
channel.
362. Amplied Siren
Build the circuit shown on the left, turn on the switch (62) and you
will hear a very loud siren. Turn off the switch (62) and the siren will
go off. In this circuit, the amplier (14) is taking the output from the
3-in-1 (11), amplifying it using transistor circuits like the ones you have
been learning about in previous projects, and then sending the amplied
signal to the speaker (93).
363. Amplier Gain
Connect points C and D with the 1kW resistor (42) in project #362.
Turn on the switch (62) and you will hear very loud gun shots and
machine gun sounds. Turn off the switch (62) and the sounds will go off.
If you had a voltmeter, you could measure the voltage across the 3-in-1
(11) speaker terminals SP1 and SP2 to be about 10mV (10 milli-volts
or 0.01 volt), while if you measured the voltage across the amplier
(14) OUT-R terminals you would see about 1.9V. This means that the
amplier is increasing the sound signal strength by a factor of 190.
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