Hi! Would anyone like to give a brief description of how the work-
electrical principles etc? Thanks.

Hello all,

Thought id join this group to see what ideas are being flung around.

Im in my 3rd year of 4 in Electronics with AI at uni, hope i may be
able to contribute

cheers
Scott

Depends on the amount of doping. Most CMOS transistors fabricated
today have highly doped source and drains, sitting in a "well" of
lightly doped (opposite doping) material. The source and drains
transmit passibly, but the wells transmit very poorly.
In old CMOS designs (circa 1980), the gates and interconnect were
made of a single layer of metal. "Crossovers" were done using highly
doped underpasses (same doping as source and drain). Theses didn't
conduct nearly as well as the metal, but were generally sufficient
for local interconnect.

Tim

--- In Electronics_101@y..., Jim Purcell <jpurcell@w...> wrote:

d,

N-type has extra electrons that can be pushed around easily. P-

type has

"missing" electrons, but the "holes" can be pushed around.

I have often wondered whether a single slice of N or P type

material would

conduct. They don't make single slices of course,
they add impurities of each type to different parts of a single

slice to make

either diodes or transistors. And the process is a bit different

with Field

Effect transistors and MOS types.

Jim

I need to record on three hand held cassette recorders from another
so as to make three copies at one time. I once found a circuit that
would allow me to do that on the Net, but nave lost it. Does anyone
have such a circuit, or tell me where to find one?

Thank you for your valuable time.

Best regards,
Don
Don A. Herrington
Cebu City Philippines
Where the Mountains Meet the Sea
In the Land of Smiles

www.geocities.com/livinginthephilippines/index.html
Home of the "Living in the Philippines for Expats" List

I'm a high school student with a rudimentary knowledge of
electronics. I'm building a very simple ethernet continuity tester
(testing current only, not signal quality), and using CMOS NAND logic
on the board. (Radio Shack boards can be a major pain, if you didn't
already know. Anyone have a better solution for someone without a
laser printer and little cash? Back to the question...)

I realised that having the device on with no wire plugged in
wouldn't be the best thing for the CMOS, but I just can't remember
where I have to stick a resistor (and what resistance) to pull a high-
Z (cable disconnected) signal to low.

Back to playing with a school copy of Proteus and laying out this
silly board (gave up on 2-side circuit, too much of a pain).

-Ben Stiglitz

--- In Electronics_101@y..., Jim Purcell <jpurcell@w...> wrote:

Tako,

Can anyone give me some guidelines about the kind of signal
appropriate to feed an audio line input? (i.e. the RCA jacks on an
amplifier/receiver).

about .5 V RMS. (ac) is a pretty good value.

.776 VRMS=0db on most -4 consumer line level gear.

Karl M

开云体育

Seeing as how someone here has had the experience....

I used the stereo miniplug method to attach a small tape
player/radio to a home stereo/amp.

I think it happens about this time of year... when it starts getting
cold.

I could swear (and routinely do so at the thing when this
happens), the plug seems to no longer fit. IOW, it gets so the
plug is no longer seated firmly in the player's ear jack.

Anyone know why?

a. Does the cold shrink the plug (but not the jack too???),
b. the metal loses its firmness and loses springy character,
c. some strange metal-to-metal conduction effect from cold,
d. dampness (instead of cold),

I would gladly rip out the minijack and substitute a 1/4" but
there's no room in the walkman.

BTW- When connecting to amp with a longer cable, I also get
weird "short wave" reception on the AM band. (Hint: Most people
know how the earphones to walkmen act as antennas--BUT
THAT ONLY APPLIES TO FM. Also, few radio portables seem to
bother with AM antennas.)



From an old post:

[Larry Hendry]

I agree with Jim on size. The 1/4 phone jack has long been

standard

for audio patching. The nice thing about that standard is that

you

can find many sources of these ready made or custom made.
Personally, I prdfer to spend time on circuits and leave the

cable

soldering to somone else. I just soldered so many in my life, I
would rather not.

Now, whether you use 1/4 mono 2 conductor, or 1/4 3

conductor TRS

(tip, ring, sleeve) often called stero, really depends on your
application.

Larry Hendry


--- Jim Purcell <jpurcell@w...> wrote:

andrij,

I'm building a couple simple audio circuits, but want to be

able

to use

modular input devices.

Larger jacks are better unless you plug them in only on rare
occasion.

Jim

__________________________________________________

Do You Yahoo!?
Make a great connection at Yahoo! Personals.

You don't need to use the clock on a JK is you want to operate it as
a RS. Forget about the J,K, and CLK inputs (ground them) and only use
Set and Reset inputs. That will make it a fully RS flip flop. You'll
even get an unknown state when Set and Reset are active :)

Mounir


--- In Electronics_101@y..., "Tim" <onesize_fitzall@y...> wrote:

Yes, a JK is functionally equivalent if R and S are mutually
exclusive. This assumes, of course, you want a clocked version of

an

SR.

Tim

--- In Electronics_101@y..., "Mounir Shita" <mshita@c...> wrote:

As far as I know, RS flip flops can't be found within the normal

74-

family or 4000-family. Maybe there is a special part out there
somewhere. But JK are the same thing (almost).

Mounir


--- In Electronics_101@y..., drewcook2000@y... wrote:

Hey i use workbench a lot in school. I went to make a prject

that

used a bunch of rs flip flops but i couldt find them. does

anyone

actuly maek RS flip flops or do i just have to make due with

JKs??

Yes, a JK is functionally equivalent if R and S are mutually
exclusive. This assumes, of course, you want a clocked version of an
SR.

Tim

--- In Electronics_101@y..., "Mounir Shita" <mshita@c...> wrote:

As far as I know, RS flip flops can't be found within the normal 74-
family or 4000-family. Maybe there is a special part out there
somewhere. But JK are the same thing (almost).

Mounir


--- In Electronics_101@y..., drewcook2000@y... wrote:

Hey i use workbench a lot in school. I went to make a prject

that

used a bunch of rs flip flops but i couldt find them. does

anyone

actuly maek RS flip flops or do i just have to make due with JKs??

As far as I know, RS flip flops can't be found within the normal 74-
family or 4000-family. Maybe there is a special part out there
somewhere. But JK are the same thing (almost).

Mounir

How about a soft copy you can print out? If so, go to
www.freetradezone.com - They have millions of datasheets for all
kinds of components. Just register (free), search for the part,
download the pdf and print it out.

Mounir

I am a student goign to shcool for basic elctronics. DOes it have to
be about telecomunications. If nto i can probably give you a couple
of ideas that i am going to make.

Hey i use workbench a lot in school. I went to make a prject that
used a bunch of rs flip flops but i couldt find them. does anyone
actuly maek RS flip flops or do i just have to make due with JKs??

living,

I plan to use the earphone output as you say, Jim. But the circuit I
saw had some kind of splitter, fairly common I understand,

Since the output of the cassette machines will be rather high and you will
want to the volume up on the source machine you could use a number of say,
ten thousand ohm resistors, tied together at the source speaker end and one
for each recorder input. The grounds for all machines would be connected
together. The resistors will give you some isolation machine to machine and
reduce the level so it won't overload the mic input.

Jim

Tim,
Most CMOS transistors fabricated

Actually there are no cmos transistors, MOS, yes. The C in CMOS means
'complimentary' as in one N type and one P type. Together they form a very
high impedance input in CMOS chips. The high input Z (impedance) is also whey
those devices are so sensitive to static.

Jim

living,

I need to record on three hand held cassette recorders from another
so as to make three copies at one time. I once found a circuit that
would allow me to do that on the Net, but nave lost it. Does anyone
have such a circuit, or tell me where to find one?

Tape recorder microphones used to be high impedance, I'm not sure what
impedance they are these days, but probably fairly high. Are you recording
the three machines from the earphone output of another? The earphone output
is low impedance so you can probably connect all three cassette mic inputs
together with no problem. Try it, you may like it. :-)

Jim

quant,

I think it happens about this time of year... when it starts getting
cold.

I've never had that experience, however there are a lot of those mini
connectors, are you always using the same earphones?

BTW- When connecting to amp with a longer cable, I also get
weird "short wave" reception on the AM band.

That's nothing, many years ago I fixed up an old reel to reel tape machine
and connected a long extension to the mic input. Before I connected the mic
to the extension I grounded the center lead and got a local radio station
just as clear as if it were coming from a tuner. In fact I recorded music and
programs. Audio amplifiers can sometimes rectify (detect) RF signals, in this
case the mic cable was a perfect tuned circuit for the station and the tube
amplifier in the tape machine was a detector.

As for headphones causing short wave stations on an AM radio, the earphone
'antenna' must be de-tuning the input circuit as well as picking up the SW
station. RF circuits are strange creatures and sometimes produce some
strange results. Maybe it's those solar flares. :-)

Jim

Hi!
Welcome to the troublesome world of RF!! Could you tell us why you
need a 50Mhz oscillator? Does it have to have tunability? If not, why
not a crystal oscillator?

C U