Chip with simple program for Toy

[John Bokma]

Dave wrote:

Heh. Real bright.

I am sure you will be able to get there if you stop trying so hard.

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

 

[Bob Monsen]

htewam@yahoo.com wrote:

Hi Ed ... that was exactly the approach that I tried before (with the
'travel' transformer)... it just didn't give me enough current on the
output -- presumably it had a low number of turns. I think Larry
(above) gave me something to run with but thanks for the feedback!

The number of turns defines the voltage ratio. For a 110 to 220
transformer, the ratio is 1:2. This is also true of a 12 to 24 transformer.

I'm guessing your source is not keeping up it's part of the bargain, and
drooping under load. That is, unless there is something sinister about
the travel transformer that we don't know about.

You may not know that you'll have to supply a bit more than twice the
current at 12V than the 24V device needs. A transformer will keep
constant volts * amps (except for losses). Thus, you'll need to supply
at least 4.2A at 12V to keep up with your 50W motor.

Larry's suggestion also discards any isolation between the load and the
source. This may not be an issue for you, but then again, it may.

---
Regards,
Bob Monsen

 

[Larry Brasfield]

"Bob Monsen" <rcsurname@comcast.net> wrote in message
news:ZcydnXyHiuzihTPfRVn-sw@comcast.com...

htewam@yahoo.com wrote:
Hi Ed ... that was exactly the approach that I tried before (with the
'travel' transformer)... it just didn't give me enough current on the
output -- presumably it had a low number of turns. I think Larry
(above) gave me something to run with but thanks for the feedback!


The number of turns defines the voltage ratio. For a 110 to 220 transformer, the ratio is 1:2. This is also true of a 12 to 24
transformer.

I'm guessing your source is not keeping up it's part of the bargain, and drooping under load. That is, unless there is something
sinister about the travel transformer that we don't know about.

You may not know that you'll have to supply a bit more than twice the current at 12V than the 24V device needs. A transformer will
keep constant volts * amps (except for losses). Thus, you'll need to supply at least 4.2A at 12V to keep up with your 50W motor.

Losses are a big issue when a transformer is used at a
fraction of its design voltage. The OP's 2.1 A load, if
taken from a 110 to 220 transformer secondary, will
require a 460 VA transformer. The fact that the load
is only 50 VA means a much larger transformer would
be required, about 9 X. By using the secondary of a
50 VA transformer as I suggested, there is much less
iron and copper put to waste. (Copper is wasted due
to having 9 X as many turns as are needed for the core.
Iron is wasted to hold all that extra copper.) There is
some waste with my suggestion too, but not so much.
A dedicated 12 to 24 VAC autotransformer could be
built without the wasted copper of a 110 VAC primary.
But that waste nominally only about half the copper.

Larry's suggestion also discards any isolation between the load and the source. This may not be an issue for you, but then again,
it may.

When the OP stated "isolation isn't an issue so I could go
with an Autotransformer", I took him at his word, assuming
he understood the loss of isolation.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[John Larkin]

On 13 Jun 2005 16:04:46 -0700, "Bret Cahill" <BretCahill@aol.com>
wrote:

Electrons won't work, but it's not hard to

whack duterium with duterium or tritium

ions to get fusion...

This was supposed to replace lasers compressing/heating a glass capsule
of D2 but either the energy density isn't as high as lasers or
something.

You need density to get worthwhile fusion output. If you accelerate
one duterium ion at another, or at a lump of same, that takes a lot of
energy, and most of the time they'll just bounce off one another and
not fuse. If the fuel is dense and very hot, a missed collision wastes
no energy and the nuclei have many, many chances to try it again until
they finally connect and fuse. Stars do it by gravity, and h-bombs use
a fission bomb to briefly achieve the sort of temperature and density
needed to get productive fusion. Just accelerating particles isn't
enough.

John

 

[ehsjr]

Larry Brasfield wrote:

Losses are a big issue when a transformer is used at a
fraction of its design voltage.

<snip>

Your solution not only saves on the very real "technical"
losses, it also avoids the "wallet" losses incurred with
the 110:220 transformer my post mentions. I just looked at
the prices for the kind of transformer I had in mind - ouch.
We're talking the 100 dollar neighborhood. Should be able to
get something at 24V ct around 5 amps for around $25.

Sounds like your idea is a winner.

Ed

 

[John Bokma]

Dave wrote:

your witty response - ego I suppose. Have at it son. I'll be back the
next time I need something.

Sure, and you probably are going to do that the "smart" way again. Look at
how other people compose their subjects. Who is the person with an ego
problem? Yup, *you*.

A subject is a subject, not a place to put an off topic "funny" sentence.
Try to give a short and exact description of your problem. More people who
can help you will read it.

You get help here for free. You are wasting the time of people who decide
to read your post, but can't help you. You mislead people.

So who is the person thinking he's a smartass? Yup, *you*.

Have you learned anything from this? I am sure no. Because of your
"little" ego problem.

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

 

[Fred Abse]

On Mon, 13 Jun 2005 05:00:08 +0000, Don Kelly wrote:

Actually, if you were in the UK where the 3 wire single phase 120/240V
(Edison) system is not used, it is called 2 phase. Where it is used it is
called 3 wire single phase. Technically the Brits are right (balanced
polyphase = N equal voltages , 360/N degrees apart) but the terminology
single phase 3 wire is a historical rather than a strict technical
description dating back to Edison where it was used for DC.

"Single phase, 3 wire" is not instantly grasped by people unfamiliar
with North American practice. On the occasions I have had to describe it
to Europeans, I've tended to use such expressions as "biphase", or
" single phase, center-tapped to neutral". The easiest way to describe it
is just draw the damn thing.

P.S love the Leacock quote

Well, he *was* a compatriot of yours (at least in later life). I'm damned
if I can find my copy of "Literary Lapses". I had to use the Web to check
I'd remembered it right.

Another I like goes something like "If you stick your thumb between two
cogs, you keep on going in until the machinery is arrested by your
suspenders"


--
"Electricity is of two kinds, positive and negative. The difference
is, I presume, that one comes a little more expensive, but is more
durable; the other is a cheaper thing, but the moths get into it."
(Stephen Leacock)

 

[John Bokma]

Dave wrote:

Right, ego is a long winded response, or a lesson... You're trying so
hard to be right, and you have all the evidence in the world to be
right, that's ego.

No, that's being right. Trying to say that *you* did nothing wrong is just
being plain stupid.

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

 

[John Bokma]

Dave wrote:

I got what I wanted, my goal was fullfilled

and time of some people wasted. Did you pay them for your time?

If you had picked a good subject people could have read more selective.

Imagine that everybody here posts "Oh boy, Me needs help" etc subjects.
But wait, you are to stupid to understand my point, even after several
explanations.

Maybe instead of being a keyboard cowboy, and a Usenet hero you should
read this article and maybe, maybe you are able to learn... a lot...

http://www.catb.org/~esr/faqs/smart-questions.html

- I ALWAYS get help here

and will continue to do it my way, because it works me.

but it wastes time of other people. Do you pay them? No. Again, imagine
all people here posting stupid subjects and being a smart ass like you.

How readable does this group become then? Use your brain for a little
while.

Talk about ego, you want me to do what works for YOU, why whould I?

Because you need help smart pants.

There's no lesson from you,

The problem resides between the chair and the keyboard or in short:
*you*

why would I take one from you? What have
you done that would enroll me to see your way except be sarcastic?

Well, take it from this guy then:
http://www.catb.org/~esr/faqs/smart-questions.html

Or just look at the subjects in this group. How many are written by the
dumbest member of the Homer Simpson fanclub? Yup, one. It's yours.

[ idiot's rambling snipped for brevity ]

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

 

[Bob Monsen]

soolun@webtv.net wrote:

I need help in using a power mosfet to switch on and off 140 VDC. The
current is approximately 25 amps. The power will be on for one second
at a time, then off for twenty seconds. I have an old part number IRF
243, but it is no longer available. A mosfet in that class, 16 amp 150
volt 125 watt or higher would work. I need to know how to operate this
mosfet including how many volts to turn it on and the placement of any
resistors or other components to make it operate as a relay.

Here is a fairchild search of N-MOSFETS that will possibly work:

http://tinyurl.com/95vxn

For operational information, look at the datasheets.

--
"I'm mad as hell, and I'm probably going to just sit here and take it!"

 

[Bob Monsen]

bobchabot@yahoo.com wrote:

I am working on a model that calls for 12 randomly (or appears to be
random) blonking LED's. I am a total newbie to this so I am looking
for help in working up a list of items I will need and help with the
circuit board I am guessing I will need to make these LED's blink. Any
help would be much appreciated.

You can buy blinking LEDs. Depending on your application, they may be
just right.

There are also circuits that simulate random times using shift registers
and such. They are much more complex.

I'd just go with the self-blinking LEDs. In that case, you need a
voltage supply, and a resistor for each one. Try 1k and a 9V battery.

--
"I'm mad as hell, and I'm probably going to just sit here and take it!"

 

[Matthias Melcher]

Serach for Nluetooth Modules with builtin antennas and serial output. You
must program those modues to have an ID and password, but then you simply
connect them to your microcontroller and they appear (mostly) like a simple
serial cable between your PC and uC. This is especially great if you host
computer has builtin BT (Many PCs, Laptops, but also phones and handhelds).
Don't forget the built-in antenna, or you are up for a lot of trouble.

There are a lot of HF tranceivers out there, to that have a serial port.
However, you need two, and they do not have a protocol. You'd have to take
care of checksums, bad connections etc. yourself. BT on the other hand is an
all-or-nothing connection. Your bytes will either be there or not, but you
will never get faulty bytes.


<denidoank@gmail.com> schrieb im Newsbeitrag
news:1118967112.110103.227080@f14g2000cwb.googlegroups.com...

Hi...I need help to make system with wireless connection. There are
devices that send input to uC (8052) on wire less connection, and then
the uC connect to PC. One alternative that I can use is blue tooth, but
I don't know what to do with that...any body can help me...I have
search in google about tutorial, but I don't find one that easy to
understand....or any other suggestion about wireless connection....?
Thanx b4

 

[Bob Eldred]

<bobchabot@yahoo.com> wrote in message
news:1118979455.508549.119990@o13g2000cwo.googlegroups.com...

I am working on a model that calls for 12 randomly (or appears to be
random) blonking LED's. I am a total newbie to this so I am looking
for help in working up a list of items I will need and help with the
circuit board I am guessing I will need to make these LED's blink. Any
help would be much appreciated.

If it were me, I'd develop a single chip solution using a cheap PIC
microprocessor with only 12 LED's, 13 resistors and a capacitor as
peripheral components, nothing more. I'd use a two port processor and drive
the 12 LED's with 12 of the 16 available bit lines. I'd run an internal
oscillator and generate a low speed clock. I'd use this to run a 256 bit,
maybe longer, pseudo-random shift register in eight or more of the
processors registers. I would tap the registers at various points and output
those signals to the LED ports. As the processor runs, the LED's would blink
on and off in a random way. It sounds complicated but is really quite simple
and is all accomplished in software (code). If you want more information or
help with code, etc. please e-mail me at nsmontassocatyahoodotcom. Remove
the ns from the beginning and put the normal @ and . in their places.
Bob

 

[Larry Brasfield]

<thomson.eric@gmail.com> wrote in message
news:1119035364.768653.65170@g49g2000cwa.googlegroups.com...

I have been frustrated for months working through an introductory
circuits book, as I want to build many of the circuits, but many of
them include constant current sources. Why is it so easy to find
voltage sources at your local store (i.e., batteries!), but searching
for current sources on the web leads to a complicated bunch of circuit
diagrams?

Your desire to build many circuits but not any of the
simpler current sources is a puzzling combination.

Here is my naive question: using thevenin-norton equivalent circuits,
couldn't I transform a battery (i.e., voltage source) into the desired
equivalent current source using Vth=InorReq. That is, can I put a
voltage source in series with a resistor (as opposed to its equivalent,
a current source in parallel with the same resistor)? What is the
problem with doing that?

Maybe nothing. How much of a current source do you want?
How constant does it have to be versus terminal voltage?

Does anyone know where I could buy a cheap but reliable current source?

Your subject indicates you want to build a current source.
If that is out of the question, one of these parts,
http://www.rohm.com/products/shortform/26rstr/rstr_index.html
together with a battery could be called a "current source".

You can use a JFET, with its gate connected to its
source, as a current source. Put a variable resistor in
series with the source to adjust its value downward.
Somebody used to sell a two-terminal current source
which was just a JFET hooked up that way.

Why is this so hard?

It's not.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[Tom Biasi]

<thomson.eric@gmail.com> wrote in message
news:1119035382.037627.145820@g47g2000cwa.googlegroups.com...

I have been frustrated for months working through an introductory
circuits book, as I want to build many of the circuits, but many of
them include constant current sources. Why is it so easy to find
voltage sources at your local store (i.e., batteries!), but searching
for current sources on the web leads to a complicated bunch of circuit
diagrams?

Here is my naive question: using thevenin-norton equivalent circuits,
couldn't I transform a battery (i.e., voltage source) into the desired
equivalent current source using Vth=InorReq. That is, can I put a
voltage source in series with a resistor (as opposed to its equivalent,
a current source in parallel with the same resistor)? What is the
problem with doing that?

Does anyone know where I could buy a cheap but reliable current source?
Why is this so hard?

A constant current source would keep the current constant as the load
changed. If the load were a small percentage of the voltage source's
internal resistance the small changes in load would be small compared to the
source resistance and the current would change very little.
Examine a 12 volt source with a series resistance of 1 Meg. Ohm. How would
the current change as the load varied from 100 ohms to 1K ohms?
Tom

>

 

[Rich Grise]

On Fri, 17 Jun 2005 12:09:24 -0700, thomson.eric@gmail.com wrote:

I have been frustrated for months working through an introductory circuits
book, as I want to build many of the circuits, but many of them include
constant current sources. Why is it so easy to find voltage sources at
your local store (i.e., batteries!), but searching for current sources on
the web leads to a complicated bunch of circuit diagrams?

Here is my naive question: using thevenin-norton equivalent circuits,
couldn't I transform a battery (i.e., voltage source) into the desired
equivalent current source using Vth=InorReq. That is, can I put a voltage
source in series with a resistor (as opposed to its equivalent, a current
source in parallel with the same resistor)? What is the problem with doing
that?

Does anyone know where I could buy a cheap but reliable current source?
Why is this so hard?

If a current sink will do, then you can do it with an NPN transistor,
a couple of diodes, and a couple of resistors.

"output"
|
|= x mA
|
C
+V ---[R1]--+--B
| E
V |
--- |
| [R2]
V |
--- |
| |
GND GND

Where R2 is sized to give .6V at your desired current, R1 is maybe
1K or so, and you should recognize the two diodes. I think a 2N4401
can go up to almost a half an amp.

Turning that into a source, with a PNP transistor, is, of course,
left as an exercise for the reader. ;-)

Have Fun!
Rich

 

[Bob Monsen]

fudj.pakar@gmail.com wrote:

I'm a relative newbie with electronics, and I'm trying to build a small
555 based adjustable timing circuit.

I have a 555 set up in monostable mode which needs to be triggered by a
positive pulse that may be longer than the desired output pulse. The
555 also needs to be immediately reset if the trigger pulse goes low.

My current circuit

* = junction
^ = bypass
T = npn bjt transistor


12v ----------*-------*
| |
1k R1 10k R2
| |
*--*-0.1uF-*----- pin 2 (trg)
| C1
IN --*--1k--T pin 3 (out)--------- OUT
| R3 |
*------^----------*----- pin 4 (rst)
| |
| 10k R4
| |
0v --------*----------*


Current problems:

1. With the RESET pin connected as in the diagram above, the timer
output (OUT) does not pulse. It remains high as long as the input (IN)
is high and goes low when IN is low.

The chip is probably still in reset when the trigger pulse comes in.

2. If the RESET pin is disconnected and left floating, the output will
pulse when IN goes low to high, which is correct. However, it also
pulses on the high to low edge if it occurs after the initial output
pulse is complete.

This may be caused by improper power supply bypassing. If so, you need a
0.1uF cap between vcc and gnd.

Any help is greatly appreciated.

-Frank

If you have an AND gate laying around, you can use that to cut off the
pulse. Instead of tying reset to IN, tie it to Vcc. Then, attach IN to
one input of the AND gate, and the output of the 555 to the other. Now,
when you bring up the input, the pulse should be seen by the chip, and
the output will be gated by the input, just like you want.

There may also be a way to fool the reset, but it may not be portable
across different version of 555.

--
"I'm mad as hell, and I'm probably going to just sit here and take it!"

 

[Bob Monsen]

thomson.eric@gmail.com wrote:

I have been frustrated for months working through an introductory
circuits book, as I want to build many of the circuits, but many of
them include constant current sources. Why is it so easy to find
voltage sources at your local store (i.e., batteries!), but searching
for current sources on the web leads to a complicated bunch of circuit
diagrams?

Here is my naive question: using thevenin-norton equivalent circuits,
couldn't I transform a battery (i.e., voltage source) into the desired
equivalent current source using Vth=InorReq. That is, can I put a
voltage source in series with a resistor (as opposed to its equivalent,
a current source in parallel with the same resistor)? What is the
problem with doing that?

Does anyone know where I could buy a cheap but reliable current source?
Why is this so hard?

You can buy a constant current source. I have a cheap one myself. It is
basically a power supply with a voltage source and current limit. Turn
the current to 0, short the output, turn the voltage all the way up, and
then adjust the current to your liking. You can get them here:

http://www.mpja.com/

You can also build a constant current source, given a voltage source. An
LM317 voltage regulator makes a good one. It tries to keep the voltage
between it's output and adj terminal at 1.24V. Thus, if you put a
resistor of value R on the output, and connect the adj terminal after
it, before the load, the LM317 will try to adjust the voltage so that
there is a constant 1.24/R A across the load. If you use an R = 100, for
example, then it will try to keep 12.4mA across the output by varying
the output voltage. Note that it will only be able to adjust the voltage
within the limits of the original voltage source, minus some for
whatever the LM317 + resistor needs, probably 3 or 4 volts.

--
"I'm mad as hell, and I'm probably going to just sit here and take it!"

 

[Bob Monsen]

davidd31415 wrote:

Has anyone here damaged or known someone who has damaged 'sensitive'
electronic devices with ColdHeat? I've heard only terrible things
about it from people I know who solder on a regular basis and decided
not to try it out for that reason alone, but I am curious about this
because it seems "sensitive" devices are going to be sensitive to both
heat and currents; I've listened to one-sided arguments claiming that
the current would pose less of a threat than the heat and am interested
in investigating that claim further.

I have one. It uses large currents to melt the solder. It sparks when
you touch it to metal. However, it doesn't have enough oomph for even
small soldering jobs. Also, there are warnings about using it on
'sensitive' electronics. I wouldn't recommend it.

 

[johnoke]

pretty cheap replacement here:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5782103890&rd=1&sspagename=STRK%3AMESE%3AIT&rd=1