You can find all the information you need at the library (any library). I understand that the instructor said all available sources but I don't think he means to have me design it for you. As someone who has never went to college and is self taught I know the value of finding the sources of information. I'll give you some basic information and you will have to find the values/formulas yourself.
For the power supply you'll have an AC input(120 VAC). For the output I believe the voltage needed is maybe 5 volts (Don't have one on hand). The steps are below.
1.) You need to step the AC voltage down to a "workable" AC voltage. Hence the transformer. Use the X:Y rating on the transformer to determine your final AC voltage 1:2 would be 60 VAC 1:4 would be 30 VAC etc.
2.) Now that ugly AC needs to be "massaged" into some workable DC voltage. Let's start with the 4 diodes. These will be made into a bridge rectifier (FYI, you can buy these as one package that gives you cleaner outputs.) These will be arranged to make the negative portions of the wave positive. Since I'm used to Navy training I won't use the Navy terminology for what the waveform will look like out of the rectifier, suffice it to say the wave will look like a bunch of hills on the 0 Volt line. Again, you have to figure out the values and arrangement of the diodes.
3.) Next you have to "knockdown" the hills to a DC voltage. Using a capacitor(s) you can stabilize the wave to get a somewhat flat DC voltage. You can manipulate the final DC voltage using caps and resistors to get a final DC out.
4.) That should be it. The walkman will have some voltage cleanup in it so you can be somewhat ugly with the output voltage.
For the amplifier:
1.)The 2N2222A (if you look in the spec book) can be made to output a gain from 100 to 300. You need to find at what collector current and collector emitter voltage is needed to attain this.
2.) Because of the level of collector current needed you will have to play with the input resistor to get your 1Mohm impedence.
3.) You'll have to get out the ol' books to calculate the values of resistors.
5.) Watch out, this baby will get HOT.
Good luck,
--------------------------------------------------------------------------------------------
Randy McHugh
Optimum Design Inc.
266 Corporate Drive
Madison, WI 53714
Voice: (608) 243-9418
Fax: (608) 243-9420
Email: [log in to unmask]
-----Original Message-----
From: *Crystale "The Angel" Vail* [SMTP:[log in to unmask]]
Sent: Monday, November 30, 1998 2:12 PM
To: [log in to unmask]
Subject: [DC] HELP!!!!
Hello,
I am a college student and this is my first time using the forum.
Anyway, I need help with two engineering projects I have been assigned.
Don't worry, you won't be helping me to cheat or anything because we have
been advised to access all available resources.
The first assignment is to build a power supply. I don't even know where
to start!!!
The power supply has to be able to run the tape deck of a walkman. The
transformer has to step the voltage down from 120Volts to about 4.5Volts.
There's four diodes connected creating a 4-way rectifier. Theres also a
resistor, capacitor, and zener diode connected in the circuit.
The second assignment is to build a class A amplifier with maximum
semetrical swing and 45dB of gain or more, using a 2N222A transistor and 1
meg of input impedeance or more.
I don't even know what half of these things mean. Also, for both
projects, we need to find the values of all of the components, they are
not given. Any help would be greatly appreciated. Thank you for your
attention.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Crystale Angel Vail
Morgan State University
1700 East Cold Spring Lane
Harper-Tubman room 367
Baltimore, MD 21251
(410)319-1651
[log in to unmask]
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"The thing that goes the farthest
towards making life worth while,
That costs the least, and does the most,
is just a pleasant smile."
--Wilbur D. Nesbit
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