Chip with simple program for Toy

[Andrew Holme]

henszey@gmail.com wrote:

Hello,

This is my first time posting to USENET. I was wondering if anyone
could help me figure out if I have the correct circuit for what I am
trying to do. I have followed other peoples schematics before, and
this is the first time that I have tried to make something for myself.

You can see the schematics that I drew up here:
http://img68.echo.cx/my.php?image=schem1wn.png

I want to run 4 things off of one power supply. The 15V 4.5A is an old
laptop power adapter. The two fans run at 12V and .01A-.02A. The LED
runs from 3.5V-4V. The peltier will run upto 15V and 15A. I did'nt
have any images for the fans and peltier so I just used some random
ones.

What I don't understand is does a device draw as many amps as it
needs? like the fans and the LED or does that need to be limited some
how?

Thanks

With the fans, you're OK - they'll "draw as many amps as they need," but you
need a current-limiting resistor in series with LED. You would be
better-off connecting the LED, in series with a resistor, across the 12V or
15V supply. Forget about VREG1 altogether. Calculate the LED current using
Ohm's law:

I = (Vs - Vf) / Rs

Vs = Supply voltage
Vf = Approximate forward voltage drop across LED (3.5V ish)
Rs = Series resistor

You need decoupling capacitors (try 100nF) on the input and output of the
other (remaining) voltage regulator.

 

[Rheilly Phoull]

One day henszey@gmail.com got dressed and committed to text

Hello,

This is my first time posting to USENET. I was wondering if anyone
could help me figure out if I have the correct circuit for what I am
trying to do. I have followed other peoples schematics before, and
this is the first time that I have tried to make something for myself.

You can see the schematics that I drew up here:
http://img68.echo.cx/my.php?image=schem1wn.png

I want to run 4 things off of one power supply. The 15V 4.5A is an old
laptop power adapter. The two fans run at 12V and .01A-.02A. The LED
runs from 3.5V-4V. The peltier will run upto 15V and 15A. I did'nt
have any images for the fans and peltier so I just used some random
ones.

What I don't understand is does a device draw as many amps as it
needs? like the fans and the LED or does that need to be limited some
how?

Thanks

Yup, things that are designated as 12v 15v etc will only take what current
they need.
An LED needs to have the current limited, your schematic would likely
'terminate' the LED. While LED's have a forward voltage you have to deduct
that from the supply voltage and then calculate a resistance that will limit
the current. Say you have taken 3.3v as the LED forward voltage, 15v - 3.3v
= 11.7v .
So to limit the current to 20mA a resistor of 11.7v / .02mA is required,
which would be 585ohms (use 680ohms). No need for the voltreg here just the
resistor. Note that you can use a lower current for very little loss of LED
output, if power is an issue 10mA or less will still give a good output
(particularly with high intensity LED')s.

--
Regards ..... Rheilly Phoull

 

[John Fields]

On 12 Apr 2005 18:47:01 -0700, greenman_11_11@yahoo.com wrote:

Hello,

For a project, I need to switch 5V DC through one of eight different
resistors using the digital outputs of a small USB data acuisition
device. I'm thinking of using a 74LS138 3 to 8 line decoder. Will this
work? I need the resistance of the chip to be 50 Ohms or less, as
anything higher will affect the project. I've come up with a design
using a relay network, but if there is a better way to do it with a
multiplexer chip, I really wnat to go that route. The resistances are
50-300 Ohms, and the 5 VDC will be coming from USB power. Thanx.

gm

---

You could use eight P-channel logic-level MOSFETS, and an HC138, like
this:

+5V>---+-----------------------------+--[R8]----S D--+---->OUT
| | G |
| +-----------+ | | |
+-|G1 Y7-|O--------------|------------+ |
A2>----|A2 Y6-|O-----------+ | |
A1>----|A1 | | +--[R7]----S D--+
A0>----|A0 | | | G |
GND--+--O|G2A- | | | | |
+--0|G2B- Y0-|O--+ +--|------------+ |
+-----------+ | | |
HC138 | | |
. . .
. . .
. . .
| | |
| +--[R1]----S D--+
| G
| |
+------------------------+



--
John Fields
Professional Circuit Designer

 

[Bob Eldred]

"Lord Garth" <LGarth@Tantalus.net> wrote in message
news:iZ16e.393$gB4.208@newssvr30.news.prodigy.com...

wade_h@saber.net> wrote in message
news:1113089916.625215.320880@f14g2000cwb.googlegroups.com...
Bob Eldred wrote:
snip
It's still common in the US where houses are mixed with small motor
installations. That unexpected 208-to-neutral is(was) a problem on
water-well controls when you needed 120v for the control-circuit.
WAde H


Around here, all delta circuits are being replaced with a wye
configuration.
The utility has standardized on this...then all the other power utilities
came
on the scene so who knows !

Well, that certainly makes more sense than some sort of a nutty asymetrical
grounding scheme. Oh well, based on the above comments, I guess anything is
possible. What does the NEC have to say about it?
Bob

 

[John Fields]

On 13 Apr 2005 08:36:45 -0700, greenman_11_11@yahoo.com wrote:

Excellent suggestion, thank you very much. Another question: Is there
a digital potentiometer available that will carry a wiper current up to
25 ma continuously?

---
Dunno.
---

If so, I could replace all those discreet
components with the pot, and get 256 resistor values instead of 8,
which would be nice for this project.

---
What would _really_ have been nice would have been if that's what you
said you wanted in the first place. However, if you can't find a pot
you can replace the '138 with an HC594/595 and accomplish the same
thing.
---

The output of my circuit will
draw up to 20 ma of current at the lowest resistor value. I looked at
the AD8400 and it will only allow a max current of 5 ma when the wiper
is set at the lowest (50 ohm) setting. Is there another device similar
to the AD8400 that is designed to carry more current?

---
Dunno.
---

Thanks for your help.

---
You're welcome.

--
John Fields
Professional Circuit Designer

 

[Lord Garth]

<greenman_11_11@yahoo.com> wrote in message
news:1113406605.108780.90630@z14g2000cwz.googlegroups.com...

Excellent suggestion, thank you very much. Another question: Is there
a digital potentiometer available that will carry a wiper current up to
25 ma continuously? If so, I could replace all those discreet
components with the pot, and get 256 resistor values instead of 8,
which would be nice for this project. The output of my circuit will
draw up to 20 ma of current at the lowest resistor value. I looked at
the AD8400 and it will only allow a max current of 5 ma when the wiper
is set at the lowest (50 ohm) setting. Is there another device similar
to the AD8400 that is designed to carry more current? Thanks for your
help.

gm

Here is some reading re digital pots:
http://pdfserv.maxim-ic.com/en/an/AN1956.pdf

Looks like the current is always going to be a problem with analog switches.
Think about the voltage drop across a digital pot...that would be the
current
through the pot times the resistance of the pot. You might have to figure a
way to buffer the signal. You should not allow the signal to exceed the
power supply limits unless you want the magic smoke to appear.

 

[ME]

Also could be a transformer.

Depending on how they are wired.

Step up
Step down
or isolation transformer.
<munglet@hotmail.com> wrote in message
news:1113410353.880284.110290@f14g2000cwb.googlegroups.com...

I have no idea what these things are called so I don't know what
terms to search on to research them.

Anyway, it looks like a metal donut that a paired set of wires wrap
around and through multiple times.

Questions:

1. What is it called?
2. What purpose does it serve?

Thanks

-Marcus

 

[Kevin Aylward]

Michael Redmann wrote:

Kevin Aylward schrieb:

Bob wrote:
It doesn't make sense that the series voltage would be anything
other than 2*V.

Indeed.

Bob and Kevin: you're absolutely right! After replying on Pete's post
I was in doubt if this strange effect could really be true. It can't.

But what's wrong with Pete's and my computation. Neither conservation
of charge nor of energy lead to the correct answer.

Of course they do. One just has to know what one is modelling!

The root cause of the confusion is that the series calculation of
capacitance is completely meaningless. I have no idea what Pete was
trying to do there.

Moving a cap and connecting one of its ends to a potential does nothing
to the charge on it or voltage across it. Hint: the voltage on a cap
don't want to change. It will conserve both charge and energy.


Kevin Aylward
informationEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[Roger Johansson]

BobG wrote:

1. What is it called?
2. What purpose does it serve?

1) ferrite bead
2) Its an inductor. Blocks hi frequencies, passes lo frequencies

It can also be called a _core_ for a toroid inductor, or a core for
a transformer, if more than one winding is used.

An information page for beginners about beads, toroid cores,
transformer cores, scroll down to see pictures:
http://sound.westhost.com/xfmr2.htm

This is one of the most known makers of toroid cores
http://www.amidoncorp.com/product.htm


--
Roger J.

 

[Lord Garth]

<henszey@gmail.com> wrote in message
news:1113437187.407942.192560@g14g2000cwa.googlegroups.com...

Here is the revised version of my circuit:
http://img91.echo.cx/my.php?image=schem26xj.png

What do decoupling capacitors do? I know that a capacitor stores a
charge, but what purpose does the decoupling capacitor serve?

When digital circuits change states, there is a very brief time when both
output devices are conducting. That creates a spike on the power rails
which you can easily see on a scope. The caps absorb much of this by
providing a local source of power.

 

[Michael Black]

Rich Grise (richgrise@example.net) writes:

On Fri, 08 Apr 2005 23:56:35 +0000, Lord Garth wrote:


"Rich Grise" <richgrise@example.net> wrote in message
newsan.2005.04.08.23.18.34.70040@example.net...
On Thu, 07 Apr 2005 09:57:02 -0700, GotCoffee wrote:

How about using the timer on an automatic coffee pot. The power
supplied
to the heating element can be used. If hooked up properly, you can
get woke up a hot cup of coffee

Yeah, and set up a hot plate with some bacon, to get that nice aroma!
This would need a cutoff timer, of course, so it doesn't burn.


Mmmm, night old unrefrigerated bacon!!!! See you in the *burpppp!*
doctors office!

OK, then. Put a microphone next to the rooster. In the morning, when
the rooster crows, the sound is picked up by the microphone, amplified,
and detected, preferably by tuning-eye tubes or LED bar graphs - an
analysis of the spectrum of the rooster's crow should help minimize
false triggering. The proper spectrum causes your DSP to output an
active signal, which is inverted turning off the NPN transistor, which
de-energizes the solenoid electromagnet that's been holding the actuator
steelie at standby. Don't forget the reverse diode! The steelie falls
into the aquarium fish net, which is attached to the lid of your Igloo
Playmate Cooler, which you have cleverly prearranged to keep the bacon
refrigerated overnight. The resulting mechanical action releases the
bacon into the pan, triggering the catwhisker microswitch that starts
the timer relay on the hot plate burner.

Perfectly healthy bacon!

Cheers!
Rich



Don't forget the release mechanism to drop the bowling ball on the sleeper,

which is bound to wake them up.

Just put the vibrator under the pillow, and wire it to a relay controlled
by the clock radio.

Sometimes a ping pong ball is the best solution.

Michael

 

[Peter Bennett]

On 7 Apr 2005 11:03:49 -0700, "Jack// ani" <nospam4u_jack@yahoo.com>
wrote:

Hi there,

In 3-phase AC wiring, if phase to neutral voltage is 110V, then why is
phase to phase voltage 220? I know phase difference between any two
phases differ by 120 degree, so they should add up to give something
less than 220V! It should sum up to give 220V if the phase difference
were 0 degree or 360degree!

Thanks

In North America, line voltage is 120 volts to ground. With three
phase power this gives you 208 volts between phases.

If the phase difference between two circuits is 0 degrees, you will
measure zero volts between them.

In normal residential wiring, we have two wires that are 180 degrees
out of phase - this gives 240 volts between "phases" (some people
object to using the term "phase in this situation...)

Although the electrical distribution system as a whole is three-phase,
individual homes are fed from the secondary of a single phase
transformer. The secondary of the transformer is center-tapped, with
the tap grounded to form the neutral conductor. There is 240 volts
between the ends of the secondary.

--
Peter Bennett VE7CEI
email: peterbb4 (at) interchange.ubc.ca
GPS and NMEA info and programs: http://vancouver-webpages.com/peter/index.html
Newsgroup new user info: http://vancouver-webpages.com/nnq

 

[Lord Garth]

"phaeton" <blahbleh666@hotmail.com> wrote in message
news:1113439919.976272.41560@o13g2000cwo.googlegroups.com...

Lord Garth sez:

Okay, take a look at the datasheet:
http://cache.national.com/ds/LM/LM386.pdf

Well, there's a novel idea! ;-) These are actually the -3's, now that
i pull them out of the tray and look at them. I had read in another
writeup (not this pdf, but another document on National's website) and
saw the "0.2%THD" bit, but i suppose i didn't see the "at 1/8W" part,
nor the "10% THD" part, or the "32-ohm" load part. Silly me...

At what point does THD become noticeable?

designs that might serve you better though most of what I find is
toob
based.

I've got some toob amp schematics too, but i'll mess around with the
solid state stuff for awhile first

Roger Johansson says:
What kind of distortion are you hearing, describe the sound please.

snip

I'm sure the perceptible THD level is different from person to person
with most easily able to hear 3%.

Notice that the gain switch is placing a cap across the internal 1.35k
resistor in the input circuitry. Recall that power amps are have a gain
that is typically less than one...your guitar is simply over driving the
amps input. The datasheet shows that you can add a variable gain
as opposed to two levels, that should help you control the distortion.
I forgot whether you were coupling the guitar to the amp through a
cap or directly. You should be using a small cap as that would block
any DC offset.

GAIN CONTROL
To make the LM386 a more versatile amplifier, two pins (1

and 8) are provided for gain control. With pins 1 and 8 open

the 1.35 kW resistor sets the gain at 20 (26 dB). If a capacitor

is put from pin 1 to 8, bypassing the 1.35 kW resistor, the

gain will go up to 200 (46 dB). If a resistor is placed in series

with the capacitor, the gain can be set to any value from 20

to 200. Gain control can also be done by capacitively coupling

a resistor (or FET) from pin 1 to ground.

 

[petrus bitbyter]

<henszey@gmail.com> schreef in bericht
news:1113437187.407942.192560@g14g2000cwa.googlegroups.com...

Here is the revised version of my circuit:
http://img91.echo.cx/my.php?image=schem26xj.png

What do decoupling capacitors do? I know that a capacitor stores a
charge, but what purpose does the decoupling capacitor serve?

In this situation the caps restrain the regulator from oscillating.

Once more, switching on the Peltier will switch off or blow your power
supply.

petrus bitbyter

 

[Roger Johansson]

phaeton wrote:

saw the "0.2%THD" bit, but i suppose i didn't see the "at 1/8W" part,
nor the "10% THD" part, or the "32-ohm" load part. Silly me...

The sound you get in those samples have 95-99% distorsion, but
they sound good, for being such a simple amplifier.

Soundclips are worth 1000 words:
http://home.mia.net/~phaeton/Anklebiter/20-65.mp3 (637KB)
Same as above, but with the guitar volume turned down to 65%. As you
can hear, the resonance of the guitar itself (it's a solidbody guitar)

I don't think it is possible to hear the resonance of the body through
all that distorsion, but I can be wrong.

is about as loud as what's coming out of the amp. Still some
distortion there. If i turn it down any lower it seems to fall under
some threshold and nothing comes out at all (which is ok, it's a
simple, cheap toy )

Strange actually. Maybe there is some non-intended noise gate function
in the circuit.

Then i tried it using a stompbox (Ibanez Tubescreamer) that wasn't
switched on. The TS does not have true bypass switching, so AFAIK in
"bypass" mode it still acts like a small preamp:

There are many versions of the TS, but you probably have one with the
fet switching, so you have both input and output buffer active when it
is in bypass mode:

Look at these web pages.
http://www.geofex.com/Article_Folders/TStech/tsxtech.gif
http://www.geofex.com/Article_Folders/TStech/tsxtech.htm

There is no distortion coming from the pedal, it's all amp.

I think the sound is very different when the TS is connected, so there
is distorsion from that too, but a good kind of distorsion I would say.

This is
with gain at 200, volume all the way up, etc. I would expect
distortion here too, and this is fine, but it remains mostly the same
as i turn the guitar down.

I'll try the resistor, like you suggested.

The amplifier is running far too high in volume if you want clean sound.
There can be some other source of distortion too.

Suggestions:

Don't use the 200 times amplification, that is far too much, unless you
want a really distorted sound.

Put a volume control at the input of the power amp, so you can control
the volume. A 500k pot would be a suitable load for the guitar.

Try replacing the loudspeaker with earphones to see if the sound is
better that way.
That will allow you to run the amp at much lower level and you get
a cleaner sound.

If you do not want to use the TS all the time you should build an input
stage for the power amp, suitable for guitar. Copy the first transistor
stage in the TS schematic. This could be the solution to get much
cleaner sound, because I suspect your amp input is not a good input
circuit for a guitar.

See that 510k resistor from the base of that transistor to +4.5V?
That is the input impedance for the transistor stage, and it is a
good load for the guitar.


--
Roger J.

 

[Roger Johansson]

phaeton wrote:

There is no distortion coming from the pedal, it's all amp. This is
with gain at 200, volume all the way up, etc.

When you strum hard on the guitar the output voltage from the guitar is
a few Volt, lets say 2Volt max.

To get maximum output from your loudspeaker you need a few Volt, maybe
5 or so.

So you need only a voltage amplification of 2-3, not 200.

If you need 200 there is some mismatch in the input circuit which is
wasting most of the signal from the guitar.

The amp only has to amplify the current, not the voltage very much.

Set the amplification to 10-20, and use a volume pot to set the input
level.
Use a 500k pot so you can connect the guitar directly to the
amp if you like.

To test the amplifier without the guitar you could connect a small
radio, mp3 player or whatever to the input of the amp and see what
happens when you give it a clean input signal.


--
Roger J.

 

[Andrew Holme]

Thomas Vogel wrote:

What´s an MVB? Is it a special IC?

It might be a multivibrator.

 

[Andrew Holme]

Thomas Vogel wrote:

Where in the web can I find maps of circuits?

They are called schematics.

 

[Lord Garth]

"Maleki" <maleki401@yahoo.com> wrote in message
news:1m3cmaktlldvt.1ea5lj43350hj.dlg@40tude.net...

On Thu, 14 Apr 2005 10:51:15 -0400, Spehro Pefhany wrote:

snip
Yes, that's also nice. But a little bit morbid, requiring
someone actually cut up the dead. In Iran's Tower of Silence
the dead is left by themselves inside such enclosures up in
the mountains, and the family climbs down back to their
houses. A couple of weeks later they go up again to gather
the remaining bones and throw them in the central ditch the
place has. the ditch is open at the top, so the bones join
the ones of earlier generations and together they watch the
Sun and stars every day and night, and the snow and rain,
for ever. I'd like to go that way.

To paraphrase 'Airplane', "I don't where I'll be then, but it's sure
not going to smell nice!"

 

[John Bokma]

Andrew Holme wrote:

Thomas Vogel wrote:
Where in the web can I find maps of circuits?

They are called schematics.

or cicuit diagrams

http://images.google.com/images?safe=off&q=circuit%20diagram

have fun :-D

--
John MexIT: http://johnbokma.com/mexit/
personal page: http://johnbokma.com/
Experienced programmer available: http://castleamber.com/
Happy Customers: http://castleamber.com/testimonials.html