Chip with simple program for Toy

[Anand Dhuru]

Hi Gene,

If what I suspect is right, this strategy will not help; you need to
get a *non-twisted* cable for your extension, even if you do use RJ45
connectors at the ends. CAT5 cable will not do!

Regards,

Anand Dhuru


genejocky2000@yahoo.com (Genejocky) wrote in message news:<5b42948.0308111446.6819f483@posting.google.com>...

Thank you John G & Anand for your help.

I'll try connecting the unused cores to the cable shielding. Perhaps
the additional shielding will sort things out.
I can't see any other reason for the cable's failure to function.

I'm trying this because I'd like to aoid buying a "usb over cat5"
setup as they are a bit excessively expensive here.
The theory behind what I'm trying sees ok though so I'm persisting
with the concept.

Thanks Gang

Gene

chrisjhodges@yahoo.com (Chris Hodges) wrote in message news:<d36a713e.0308080228.6bb01224@posting.google.com>...
genejocky2000@yahoo.com (Genejocky) wrote in message news:<5b42948.0308070128.27cb9c7a@posting.google.com>...
Hey Brett,

I'm trying to keep the USB Specs in mind (what I know of them anyhow).
If there are any specifics you could throw at me I would be very happy
to run with them.
The current process has progressed this far.
- taken functional USB a to USB b cable & cut it in half.
- crimped shielded RJ45 clips/connectors to the ends of the halves.
- used a RJ45 coupler to check the cable
- checked the wiring with a continuity tester & all seem ok.

I must admit that I have tried to send data to a printer through this
cable & found that it failed.
I'm very interested to know what is reason for this failure.

Does anyone have any suggestions??

Lack of a screen on the USB may well cause this. It's possible that
commoning-up the unused cores and connecting them to the screen at
both ends would do it. I'm still not sure why you're doing it this
way though. You can buy USB A-Male to A-female extension cables for
about the same cost as a USB cable, or buy a 5m USB cable and splice
that on the your device.

If you're trying to do more than 5m, as (I think) has been stated
earlier you _will_definately_ need an active device.

I've beeen using a USB-over-CAT5 kit (Ł225 ~ $340 I guess) for 40m +
hub and interconnects.

btw I've found that routing USB through a 4PDT switch works, although
it seems to take longer to register the device when switched in (USB
plug make power before comms, my switch doesn't).

Chris

 

[Phil Brady]

Pete wrote:

Hello,

I am trying to build a very basic parallel port interface to control a
relay. (I've copied the basic schematic, that I found elsewhere on the
web, to: http://rbanks.customer.netspace.net.au/pport.htm for your
reference.)

The problem I'm having is simple: it just won't work! : )

I've connected the 5v+ pin of my parallel port to the 4.7k resistor.
(It doesn't matter which direction the resistor goes does it?)

Correct, the resistor will fit either way round. But did you connect
to the 5 volt pin, or a data pin?

I've
then connected the resistor to the base pin (B) of my transistor (an
NPN 2N2222A). I've connected the ground pin of my parallel port to the
emitter pin (E) of my transistor. This is as much as I've built for
now as I'm not even getting a signal from my transistor! (The signal
from my transistor is supposed to trigger the relay.)

Okay, but what is the collector connected to? Do you have it connected
to the relay coil/diode and the other side of those to VCC? By Vcc it
means a supply of (say) 5 volts with the other supply rail of that
supply connected to the ground. You might have such a power supply from
a pin on the connector.

Note the diode must be fitted right way round - it prevents spikes from
the coil from doing damage at switch off.

I then send 5v+ out my parallel port (or just under 5 volts, maybe 4.8
volts). I've measured it with my multimeter. Then I put the red cable
of my multimeter on the collector pin (C) of my transistor and the
black cable of my multimeter on the emitter pin of my transistor and I
get nothing! However, when I put the red cable of my mulitmeter on the
other side of the resistor (after resistance) I get between 2 and 3
volts (I think, that's from memory). Then if I put the red cable of my
multimeter on before the resistor I get just under 5volts (probably
about 4.8 volts, but my multimeter is one of those analogue ones with
the needle so I can't be sure, it may be a little more or a little
less).


It seems everything works fine until the transistor. I would really
appreciate any help... as you can probably see from my
I-put-the-red-cable-there language, I'm very new when it comes to
electronics, but I am a great java programmer : D

Kind regards,

Pete

regards
Phil

 

[Roger Johansson]

peter.williams@lycos.com (Pete) wrote:

I then send 5v+ out my parallel port (or just under 5 volts, maybe 4.8
volts). I've measured it with my multimeter. Then I put the red cable
of my multimeter on the collector pin (C) of my transistor and the
black cable of my multimeter on the emitter pin of my transistor and I
get nothing!

A transistor works like a valve, you use the base current to open or
close it. You have not connected anything to the collector yet, that
is why you get no reaction.
It is like opening and closing a water valve without connecting it to
a water supply, nothing happens at the opening of the valve.

Connect a resistor, 1k for example, between the collector and +5V and
you will see a reaction on the collector.

When the transistor is letting current through the voltage on the
collector will be rather low, close to ground.
When the transistor is not letting current through the voltage on the
collector will be high, because it is connected to +5V via the
resistor you connected between the collector and +5Volt.

This is how you use a transistor.
It amplifies a small current coming in through the base into a bigger
current through the collector-emitter to ground.
The voltage on the collector will be high when the voltage on the base
is low, and vice versa, so the transistor inverts the signal.

You should use a base resistor between the output from the port and
the base of the transistor, this can be 10k for example.

If you replace the 1k collector resistor with a 300Ohm resistor and an
LED in series you can turn the LED on and off with the port output.
The long lead on the LED is connected to the more positive point.


--
Roger J.

 

[Si Ballenger]

On 13 Aug 2003 07:01:30 -0700, peter.williams@lycos.com (Pete)
wrote:

Hello,

I am trying to build a very basic parallel port interface to control a
relay. (I've copied the basic schematic, that I found elsewhere on the
web, to: http://rbanks.customer.netspace.net.au/pport.htm for your
reference.)

The problem I'm having is simple: it just won't work! : )

I've connected the 5v+ pin of my parallel port to the 4.7k resistor.
(It doesn't matter which direction the resistor goes does it?) I've
then connected the resistor to the base pin (B) of my transistor (an
NPN 2N2222A). I've connected the ground pin of my parallel port to the
emitter pin (E) of my transistor. This is as much as I've built for
now as I'm not even getting a signal from my transistor! (The signal
from my transistor is supposed to trigger the relay.)

I then send 5v+ out my parallel port (or just under 5 volts, maybe 4.8
volts). I've measured it with my multimeter. Then I put the red cable
of my multimeter on the collector pin (C) of my transistor and the
black cable of my multimeter on the emitter pin of my transistor and I
get nothing! However, when I put the red cable of my mulitmeter on the
other side of the resistor (after resistance) I get between 2 and 3
volts (I think, that's from memory). Then if I put the red cable of my
multimeter on before the resistor I get just under 5volts (probably
about 4.8 volts, but my multimeter is one of those analogue ones with
the needle so I can't be sure, it may be a little more or a little
less).


It seems everything works fine until the transistor. I would really
appreciate any help... as you can probably see from my
I-put-the-red-cable-there language, I'm very new when it comes to
electronics, but I am a great java programmer : D

Kind regards,

Pete

To test your transistor, set your meter to measure resistance,
connect the red meter wire to the transistor collector and the
black meter wire to the transistor emitter. The resistance
reading should be high. Then connect the + terminal of a 9v
battery to the 4.7k resistor (the other end of the resistor is
connected to the transistor base). Connect the - terminal of the
9v battery to the transistor emitter. The meter resistance
reading should now go very low. If this works, then disconnect
the meter and connect your relay setup to the transistor. Test it
using the 9v battery in place of the parallel port pins. If the
relay works, then try connecting the transistor to the parallel
port pins and see if it works there. If it does not work there,
then you may not be connecting to the right parallel port pins
that can supply a couple of ma. Pins 2 through 9 are the ones
usually used in this type of setup. I've got a web page below
that shows a simple web cam video switcher I made that I control
via the web. Bottom link shows it in action. You can control that
relay via the net too. ;-)

http://www.geocities.com/zoomkat/ppswitcher.htm
http://www.geocities.com/zoomkat/ppswitcher-demo.htm

 

[Pete]

Firstly, thanks so much for the replies! It's been so helpful to this
electronics ditz (so that's what a transistor does! : ) It's finally
working now... with one last little problem.

I put around 10 volts "into" the relay. This is the current that is
supposed to be switched (based on the signal from my parallel port).
So I put 10 volts in and sure enough, nothing comes out the other side
when my parallel port is giving nothing. When my parallel port is
outputing 5 volts (actually it's just under 5 volts), I would expect
the other side of the relay to output the 10 volts I put into it.
Instead it outputs 5 volts!

Is it normal for a relay to suck up power like that? Or is it the
whole circuit?

The valve that I'm using this circuit to open and close (using my
parallel port) seems to operate well on 10 volts (I've wired up 10
volts to it directly). But when I wire up the valve to this circuit,
of course the ouput is only 5 volts and the valve doesn't work
(because, I assume, 5 volts isn't enough power for the valve to
operate).

So, if it is normal for a relay (or the whole circuit to suck up power
like that), if I want the end power to be 10 volts, I should put in,
what, say, 15 volts to the circuit?

Kind regards,

Pete

http://www.geocities.com/zoomkat/ppswitcher.htm
http://www.geocities.com/zoomkat/ppswitcher-demo.htm

btw remote control via the web of a cameara, that's pretty cool! i'm
trying to turn my garden watering on via the web!

 

[Roger Johansson]

peter.williams@lycos.com (Pete) wrote:

I put around 10 volts "into" the relay. This is the current that is
supposed to be switched (based on the signal from my parallel port).
So I put 10 volts in and sure enough, nothing comes out the other side
when my parallel port is giving nothing. When my parallel port is
outputing 5 volts (actually it's just under 5 volts), I would expect
the other side of the relay to output the 10 volts I put into it.
Instead it outputs 5 volts!

I am not sure how you have connected your components, but I will
describe how you should connect them.

The output from the parallell port should be connected to the base of
the transistor via resistor, say 10kOhm.

This resistor limits the current you are pushing into the base of the
transistor when the port output is high, that is +5Volt.
The current will be a maximum 5Volt divided by 10k, 5/10000 Amps,
which is enough to make the transistor conduct.

The input side of the transistor is the base and the emitter, the
current you send through the base to the emitter control the
transistor.

The output side of the transistor is the collector to emitter path.
You can use this to control a much bigger current than the current you
control the transistor with on the input side.

If you want to control a relay you connect the relay between a plus
voltage, +5 or +12, for example and the collector of the transistor.

When the transistor conducts current it will now pull current through
the relay and activate it.

There is one thing you should know about relays. The current doesn't
start and stop immediately because the relay coil is an inductance.
So when you cut off the current with the transistor the coil will try
to push current through it for a short time before it realizes that
the contact has been lost.

This will raise the voltage very much at the lower side of the coil.
This is the way the ignition in cars work, by the way. It creates a
spark, or it destroys the transistor.
So you must always connect a diode over the relay coil, which can lead
the current back to the positive voltage when the transistor stops the
current.

This diode must be connected to conduct current from the normally
negative side of the relay coil to the other side of the relay coil,
the positive side. During the normal operation this diode will not be
active, because it has the wrong direction to conduct, but when the
transistor cuts off the connection it will lead the electrons pumped
through the coil back to the other side of the coil.

The lower side of the relay should, when the transistor is conducting,
be very low, it is the collector of the transistor as well as the
lower side of the relay coil, so the transistor pulls down the voltage
in this point close to ground when the transistor is fully conducting.

Remember to think about limiting the current to a safe value every
time you connect a positive voltage to a negative voltage.

At the base of the transistor the base resistor limits the current you
push through the base-emitter path inside the transistor.

On the output side of the transistor you limit the current with the
relay coil in this case. It is made to be connected to a voltage
difference, if it is a 5 volt relay it needs to be connected to +5
volt at one end and ground at the other end, but now we have inserted
a transistor between the lower end of the relay coil and ground, to
steer it.

The collector will be very close to ground when the transistor is
conducting, so it will be like ground to the relay coil.
When the transistor is not conducting it will be like the lower end of
the coil is connected to nothing, just air. That is why it has to be
connected to a diode back to the other end of the coil, otherwise the
pumping action of the coil will create a spark, probably through the
closed transistor and destroy it.

The current through the relay coil when the transistor is conducting
will be limited by the resistance in the coil to a value which is
suitable, if you connect the coil to the voltage it is made for.

For this circuit to work you need to use a transistor which can cope
with the current the relay coil needs and will create.

The amplification factor of the transistor also needs to be high
enough so it can amplify the base current into a collector current
which is enough for the relay coil.
You can lower the base resistor to 1k instead of 10k to make the
transistor conduct better if it has a low amplification factor.

If the current is not enough the voltage on the collector will not be
close to ground, as it should be when the transistor conduct and the
relay is activated.


I can tell you a little more about the mystical "pump" action of
coils.

It is a problem when we use a coil in a relay, but it is a useful
feature when we want to create sparks.

The coil is kind of slow to start conducting, and it is also slow to
stop conducting, it needs to build up a magnetic field to start
conducting, and the magnetic field keeps on pumping current through it
even after we have removed the voltage over it.

This is used in cars to create sparks, as I said before, and it is
also used to ignite the current through neon tubes, fluoroscent tubes.

The fluoroscent tube is connected in series with a coil, and an
"igniter" is connected in parallell to the tube.
The igniter conducts current to begin with, and when the current has
started through the coil the igniter stops conducting, the coil pumps
current to the end of the tube, the voltage rises to thousands of
volts, a spark goes through the neon tube and the tube starts
conducting current.

The igniter may have to make several tries to get the neon tube to
conduct, that is why you see neon tubes blink a couple of times before
it starts glowing steadily.

--
Roger J.

 

[Brian]

Aaron Banks wrote:

Hi I have a series RLC circuit (resonant) with an AC source and the
measured voltage across each component is 100 V. How can I find out
what the source voltage is and what the voltage should be across:1.
the inductor and capacitor2. the capacitor and resistor3. the
inductor, capacitor and resistor I'm thinking because the circuit is
supposed to be resonant, the capacitor/inductor cancel each other out
and the 100 V value measured across the resistor would be the value of
the AC source...Am I on the right track? Thanks! Aaron
Banksabanks@telus.net

If you put a resistor, a capacitor and inductor in series (in that
order) that is resonant:
1. the voltage across the inductor and capacitor will be zero

2. the voltage across the capacitor and resistor will be
E = Z * I
Z = square root of (R square + Xc square)
I = V / R

3. The voltage across the resistor, capacitor and inductor will be the
AC source voltage.

All this is if you have perfect components (no loses).

E = voltage across the resistor and capacitor
I = current through the series circuit
Z = impedance of the resistor and capacitor combination
Xc = capacitive reactance
R = resistor value
V = AC source voltage


--
Building user friendly software for electronics.
http://www.fncwired.com

 

[JeffM]

As a former installer (only 1-1/2 year), I agree.
I think it's a manufacturer covering his butt
(idiots who can't tell aluminum from steel,
idiots who can't figure out how to use a ladder, etc.).

...eight years of my life as the owner/operator of a ... alarm company.
... know of no failures due to the magnet losing it's strength.
Frank Pickens

 

[John]

How the heck could this happen?? Isn't there safety systems in place to
prevent this? I mean really, we have circuit breakers in our homes to
prevent mishaps. I would think that on this scale, someone would have
thought of a system to prevent this from happening.

Can anyone shed any light on the matter??? How does a whole grid overload
without something being tripped before it got to this level? Are there not
measures in place to contain a power outage?

TIA.....
John

 

[anonymous]

"John" <johncr@NOSPAMshaw.ca> wrote in message
news:tGV_a.725699$ro6.14965169@news2.calgary.shaw.ca...

How the heck could this happen?? Isn't there safety systems in place to
prevent this? I mean really, we have circuit breakers in our homes to
prevent mishaps. I would think that on this scale, someone would have
thought of a system to prevent this from happening.

Can anyone shed any light on the matter??? How does a whole grid overload
without something being tripped before it got to this level? Are there
not
measures in place to contain a power outage?

The way I understand, if a power plant, major transmission line(s), or
substation goes down, other power sources are supposed to compenstate for
the loss in supply to meet the demand and if nothing could meet the demand,
a switching station is supposed to cut off affected area. This was to
prevent overloading the lines and power plants.

I'd like to know why the power failure was so widespread today. In theory,
the power failure should have been, at worst, limited to lower New York but
something happened and several power plants are offline including all 9
nuclear plants in the affected area.

I was nearly the victim. At about 4:15 the light suddenly went dim and
flickered like there's a big energy guzzling overworked motor nearby. All
of the PCs I've had on quit right at the start of the brownout (strangely
the one Macintosh continued running fine) and the brownout/flickering lasted
for a minute before the power went back on normal. I guess the power plant
for my area was in the northern part of Michigan and a substation somewhere
kicked in, separating my area from the affected area. If I took a 30
minutes drive south, it'd be like ghost town as everything there and south
is powerless. BTW I'm near Flint, MI if anyone's trying to map the blackout
area. I do know Lansing, Fenton (south of Flint), and pretty much
everything south of those 2 cities are in nthe dark.

PS. And yes, that one Macintosh was still running unafected by the brownout.
I want the phone number to Aztec that made the power supply for my Mac so I
could get some for all of my PCs. That's a damn good power supply to
remain functional at greatly reduced power.

 

[Baphomet]

http://www.bigdoggie.net/messageboards/freespeech/msgs/posts/53129.html

"John" <johncr@NOSPAMshaw.ca> wrote in message
news:tGV_a.725699$ro6.14965169@news2.calgary.shaw.ca...

How the heck could this happen?? Isn't there safety systems in place to
prevent this? I mean really, we have circuit breakers in our homes to
prevent mishaps. I would think that on this scale, someone would have
thought of a system to prevent this from happening.

Can anyone shed any light on the matter??? How does a whole grid overload
without something being tripped before it got to this level? Are there
not
measures in place to contain a power outage?

TIA.....
John

 

[Arthur Jernberg]

What amazed me is the fact that the same geographic area was affected by a
power outage in Fall of 1965. That also was blamed on anomalies in the
"Niagara Power Grid" area. The documents produced by the electrical
suppliers and government investigators allude to implementation of
safeguards to make sure the domino effect would not happen again. Living in
the Greater Detroit Area and having just put up with no electrical service
for over 35 hours was a nuisance. There were customers in the area that
waited even longer. Personally it seems that either they did not learn or
the procedures implemented did not function per design. Either way "The
Lights Did Go Out!!"
"John" <johncr@NOSPAMshaw.ca> wrote in message
news:tGV_a.725699$ro6.14965169@news2.calgary.shaw.ca...

How the heck could this happen?? Isn't there safety systems in place to
prevent this? I mean really, we have circuit breakers in our homes to
prevent mishaps. I would think that on this scale, someone would have
thought of a system to prevent this from happening.

Can anyone shed any light on the matter??? How does a whole grid overload
without something being tripped before it got to this level? Are there
not
measures in place to contain a power outage?

TIA.....
John

 

[Bob]

"Bob" <bob@bob.com> wrote in message news:9BD0b.153034$cF.55969@rwcrnsc53...

I read about discharging potentially dangerous high voltage caps by
grounding the positive terminal to chassis ground with some resistors in
between.

I'm wondering what happens here to the charge - does it just "go away", or
is it stored in the chassis, or is the point that there's no longer a
charge
differential?

Do I then have to be careful not to touch the chassis, after discharging a
cap like this?

I ask this in reference to a component unplugged from the wall socket.

Thanks

Bob

Oops, I'm guessing the resistors heat up and there goes the charge, but if
anyone can confirm I'd appreciate!

 

[Robert Monsen]

"Bob" <bob@bob.com> wrote in message news:9BD0b.153034$cF.55969@rwcrnsc53...

I read about discharging potentially dangerous high voltage caps by
grounding the positive terminal to chassis ground with some resistors in
between.

I'm wondering what happens here to the charge - does it just "go away", or
is it stored in the chassis, or is the point that there's no longer a
charge
differential?

Its the charge difference that is dangerous (the voltage). If you touch the
two ends, that difference makes lots of charge flow through you, which is
what you want to avoid.

Do I then have to be careful not to touch the chassis, after discharging a
cap like this?

No, because now there isn't a charge differential. Its spread evenly around
in the system.

I ask this in reference to a component unplugged from the wall socket.

You should be OK.

Thanks

Bob

 

[Terry]

Terry wrote:

Melissa Frye wrote:

I (with my complete lack of and electronics background) am trying to
build a gadget that does the following:

When started makes a buzzing noise for a pre-set, but variable amount
of time (.1 to 30 secs ideally), and automatically shuts itself off.

For example
Set for 17 secs. start. Buzzzzzzzzz (for 17 secs) autoshut-off.

Or
Set for 3.5 secs. start. Buzzzzzzzzz (for 3.5 secs) autoshut-off.

Can anyone give me any assitence with this? I can find buzzers at
radioshack, but not timers like I need....

Melissa

Sounds like you could use the electronic timer panel from a
scrapped microwave oven.
Some of them have what's called "Timer Delay" IIRC. Normally I
believe Timer Delay is often used as a reminder to check on
something. many electronic timer panels have their own samll
built in power supply off of the mains voltage (115 or 230 volts,
depending where you are in the world).
Two possible methods suggest theselves?
In one method you would wire it up so that instead of switching
on the microawave to cook it operates a buzzer, for, in this case
17 seconds. Then stops.
Conversely you could use the 'buzzer' of the timing panel itself;
set the timer for 17 seconds, press start, after 17 seconds the
timer gives an audible signal that the 17 seconds has elapsed by
beeping or whatever.
Just ideas.

Second idea. IIRC one can buy a small non electronic timer at
cook-ware outlets. Some merely give a ringing or buzzing sound
when timing completes. I believe there is one that you plug your
electric appliance into. It then switches OFF when timing
completes. Whether some of those manually set ones would be
sufficiently accurate I don't know. A stop watch would also work?
Sounds like you could use a timer designed for use by amateur
photographers who develop their own film! Try a photography
supplies outfit.

 

[Fred Abse]

On Wed, 20 Aug 2003 16:37:34 +0100, Jesse wrote:

Australia has never been on the for-front of anything.

Apart from Gallipoli, and quite a few British fuckups since. Go look at
the war graves.

Grrrrrrr!

--
Then there's duct tape ...
(Garrison Keillor)
nofr@sbhevre.pbzchyvax.pb.hx

 

[Baphomet]

sales@dimco.grey.com
contact: Jeffrey S. Hartley

Melissa...I would give you further information but their website seems to be
down. They have a wide range of electro-mechanical timers (ask about their
model 300)
Explain your requirements.

Good luck

"Melissa Frye" <mfrye@surfree.com> wrote in message
news:371a4c54.0308200906.6b267b26@posting.google.com...

I (with my complete lack of and electronics background) am trying to
build a gadget that does the following:

When started makes a buzzing noise for a pre-set, but variable amount
of time (.1 to 30 secs ideally), and automatically shuts itself off.

For example
Set for 17 secs. start. Buzzzzzzzzz (for 17 secs) autoshut-off.

Or
Set for 3.5 secs. start. Buzzzzzzzzz (for 3.5 secs) autoshut-off.

Can anyone give me any assitence with this? I can find buzzers at
radioshack, but not timers like I need....

Melissa

 

[John Popelish]

Kevin wrote:
(snip)

Basically, I would like to
know of anyone has any good links to some fun stuff I could build
while (re)learning how it all works. Also, any info on where I might
find a list of chips, along with what they do would be great, too.
Anyone interested in helping and old dog learn some new tricks? Thanks
and have a great day!

I think you should dive into opamp circuits. They do more with less
than almost any other kind of active devices, except maybe for
microprocessors. They allow you to do all sorts of signal processing
and decision making things with very cheap parts (many opamps are well
under a dollar each). About all you might need in the form of test
equipment would be a used oscilloscope, to let you look at waveforms.

Here are some ap notes that catalogs some of the things you can do
with opamps:
http://www.national.com/an/AN/AN-4.pdf
http://www.national.com/an/AN/AN-20.pdf
http://www.national.com/an/AN/AN-31.pdf

--
John Popelish

 

I second the OpAmp...I started in Digital Electroinics...great stuff but
most of the connections to the real world are through OpAmps...a lot you can
do with them...
-Gary

"John Popelish" <jpopelish@rica.net> wrote in message
news:3F44051E.8A8AC25E@rica.net...

Kevin wrote:
(snip)
Basically, I would like to
know of anyone has any good links to some fun stuff I could build
while (re)learning how it all works. Also, any info on where I might
find a list of chips, along with what they do would be great, too.
Anyone interested in helping and old dog learn some new tricks? Thanks
and have a great day!

I think you should dive into opamp circuits. They do more with less
than almost any other kind of active devices, except maybe for
microprocessors. They allow you to do all sorts of signal processing
and decision making things with very cheap parts (many opamps are well
under a dollar each). About all you might need in the form of test
equipment would be a used oscilloscope, to let you look at waveforms.

Here are some ap notes that catalogs some of the things you can do
with opamps:
http://www.national.com/an/AN/AN-4.pdf
http://www.national.com/an/AN/AN-20.pdf
http://www.national.com/an/AN/AN-31.pdf

--
John Popelish

 

[petrus bitbyter]

"Kevin" <No_Fate@comcast.net> schreef in bericht
news:90482fd9.0308201408.53760092@posting.google.com...

Hello, I took basic electronics in high school some 20 odd years ago,
much of which has been forgotten (maybe just suppressed), and I would
like to get back into it. I have some renewed interest in this field
and others, such as robotics. As this will only be a hobby I don't
want to go back to school or anything, but I would like to freshen up
on ic chip usage, learn about photo sensors, stuff like that. I have
been in the auto electronics biz for nearly 20 yrs, so I do know a lot
about electrical stuff in general, but most of what I did was 12
volts, things like car alarms, stereos, remote starters, amps,
etc..but I do miss the circuitry at it's basic level. I remember in
10th grade we spent what seemed like a whole year on resistors, and
when we finally built a circuit that made an led come on, it was
exciting! Something happened, a change had been made and we could see
the results immediately. Building something from scrap parts.. a
timer, a clock, anything was a lot of fun. Basically, I would like to
know of anyone has any good links to some fun stuff I could build
while (re)learning how it all works. Also, any info on where I might
find a list of chips, along with what they do would be great, too.
Anyone interested in helping and old dog learn some new tricks? Thanks
and have a great day!

Kevin,

You was in high school some 20 years ago? Your still young! Real old timers
were in high school over 40 years ago. (So I don't call myself an oldtimer
already.)

As for your question, find a good text book. Amazone may be a good place
if you want to buy one. Your local library will be cheaper.

There are Gigabytes of hobby schematics on the internet. One off the sites
I like is:
http://www.zen22142.zen.co.uk/

So welcome back in the world of electronics.

pieter






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