Chip with simple program for Toy

"hartly" <hartlyuk@yahoo.com> wrote in message
news:1f73b571.0504050809.52056475@posting.google.com...
If a camera draws 1 amp.,and I connect it to a battery that can supply
10A,will it do any harm to the camera ,IF the volts correct for the
camera?
Thanks.
The camera draws what it needs so this is perfectly okay.

It's like saying your sink needs 5 gallons but the faucet leads to Lake
Erie.
 
In article <1f73b571.0504050809.52056475@posting.google.com>,
hartlyuk@yahoo.com (hartly) wrote:

If a camera draws 1 amp.,and I connect it to a battery that can supply
10A,will it do any harm to the camera ,IF the volts correct for the
camera?
Thanks.
It should pose no problem, as the device using the power, not the device
supplying it, determines how much current will actually flow. Attach a
(correct voltage) source to it that can supply *at least* the amperage
required, and everything should "just work".

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.
 
"Thomas Vogel" <Tommi-Vogel@gmx.de> wrote in message
news:7f88d87.0504050839.7cbf63a1@posting.google.com...
I want to construct a circuit which switch a relay by a alarm clock.
Know anyone where I can find a plan in the internet or in a book or in
a magazine?

tommi
You must define what signal the alarm clock produces before you can
get any useful responses. What is the output voltage? Is it a pulse or
a level? What are the specs of the relay you wish to use? Is the relay
supposed to stay energized until it is manually reset? Is the relay circuit
powered by a battery or a line source?

Perhaps you mean you wish to build a digital alarm clock with a relay
output?
 
"Lord Garth" (LGarth@Tantalus.net) writes:
"Thomas Vogel" <Tommi-Vogel@gmx.de> wrote in message
news:7f88d87.0504050839.7cbf63a1@posting.google.com...
I want to construct a circuit which switch a relay by a alarm clock.
Know anyone where I can find a plan in the internet or in a book or in
a magazine?

tommi

You must define what signal the alarm clock produces before you can
get any useful responses. What is the output voltage? Is it a pulse or
a level? What are the specs of the relay you wish to use? Is the relay
supposed to stay energized until it is manually reset? Is the relay circuit
powered by a battery or a line source?

Perhaps you mean you wish to build a digital alarm clock with a relay
output?
It sounds to me like he wants someone to explain how to do it, the problem
being that the chances of two people having the same clock radio is pretty
low.

I did it to one, but it was really simple because I used a clock radio
that was fairly old, and the clock was on a separate board from the actual
radio. That made it real simple to find the wire that turned on the
radio, and use it to turn on a relay.

Not that it's that much more difficult in more recent clock radios,
just that it's jammed into a smaller space. The obvious thing is to
take a clock radio that's cheap, open it up and then find the datasheet
for the clock IC. That should give information about the "alarm" output.

Of course, given the tone of the original question, it might just be
simpler to rectify the audio from the radio, easily found since it's
available on the speaker terminals, and then amplify that up enough
to feed a relay.

Forest Mims did something like this one, using an SCR to detect the
signal intended for a piezo speaker in a battery timer, which then
could turn on something more. Of course, it latched, being an SCR,
so the output was turned on even after the "alarm tone" ended.

Michael
 
Thomas Vogel wrote:
I want to construct a circuit which switch a relay by a alarm clock.
Know anyone where I can find a plan in the internet or in a book or in
a magazine?
Why not just buy a timer? You can get them with plug outputs, that can
be set just like an alarm clock, or even set with ranges, so the plug
turns on at say 9pm, and turns off at 6am.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.
 
"Michael Black" <et472@FreeNet.Carleton.CA> wrote in message
news:d2ulms$ied$1@theodyn.ncf.ca...
"Lord Garth" (LGarth@Tantalus.net) writes:
"Thomas Vogel" <Tommi-Vogel@gmx.de> wrote in message
news:7f88d87.0504050839.7cbf63a1@posting.google.com...
I want to construct a circuit which switch a relay by a alarm clock.
Know anyone where I can find a plan in the internet or in a book or in
a magazine?

tommi

snip

Perhaps you mean you wish to build a digital alarm clock with a relay
output?


It sounds to me like he wants someone to explain how to do it, the problem
being that the chances of two people having the same clock radio is pretty
low.
snip
Michael
We'll see if he ever gets back to the group...

I took apart a Garfield alarm clock last year and found it had a clock
module
that was very similar to the modules produced by National in the (what?)
late 70's through mid 80's.
 
On Tue, 05 Apr 2005 18:34:04 +0000, Michael Black wrote:
"Lord Garth" (LGarth@Tantalus.net) writes:
"Thomas Vogel" <Tommi-Vogel@gmx.de> wrote in message

I want to construct a circuit which switch a relay by a alarm clock.
Know anyone where I can find a plan in the internet or in a book or in
a magazine?

You must define what signal the alarm clock produces before you can get
any useful responses. What is the output voltage? Is it a pulse or a
level? What are the specs of the relay you wish to use? Is the relay
supposed to stay energized until it is manually reset? Is the relay
circuit powered by a battery or a line source?

Perhaps you mean you wish to build a digital alarm clock with a relay
output?

It sounds to me like he wants someone to explain how to do it, the
problem being that the chances of two people having the same clock radio
is pretty low.

I did it to one, but it was really simple because I used a clock radio
that was fairly old, and the clock was on a separate board from the
actual radio. That made it real simple to find the wire that turned on
the radio, and use it to turn on a relay.
....

I did this once with a "modern" digital alarm clock with a piezo beeper.
I just picked off the pulses to the beeper, and triggered a retriggerable
one-shot to turn on my large alarm, which was just a MVB and big speaker.
Actually, it was two MVBs, so I got a two-tone blare that really annoyed
the neighbors. ;-)

Cheers!
Rich
 
hartly wrote:
If a camera draws 1 amp.,and I connect it to a battery that can supply
10A,will it do any harm to the camera ,IF the volts correct for the
camera?
Thanks.
No. The batteries set the upper bound on how much current a load can
draw (the short circuit current) and a practical upper bound on load
current, based on the capacity (ampere hours) and internal resistance
(that lowers the voltage as the load current drops some of the voltage
across the internal resistance. But if neither of these limits is in
effect, the load just uses as much current as it needs. A bigger
battery just lasts longer.
 
"Rich Grise" <richgrise@example.net> wrote in message
news:pan.2005.04.05.21.51.55.857477@example.net...
On Tue, 05 Apr 2005 18:34:04 +0000, Michael Black wrote:
"Lord Garth" (LGarth@Tantalus.net) writes:
"Thomas Vogel" <Tommi-Vogel@gmx.de> wrote in message

I want to construct a circuit which switch a relay by a alarm clock.
Know anyone where I can find a plan in the internet or in a book or in
a magazine?

You must define what signal the alarm clock produces before you can get
any useful responses. What is the output voltage? Is it a pulse or a
level? What are the specs of the relay you wish to use? Is the relay
supposed to stay energized until it is manually reset? Is the relay
circuit powered by a battery or a line source?

Perhaps you mean you wish to build a digital alarm clock with a relay
output?

It sounds to me like he wants someone to explain how to do it, the
problem being that the chances of two people having the same clock radio
is pretty low.

I did it to one, but it was really simple because I used a clock radio
that was fairly old, and the clock was on a separate board from the
actual radio. That made it real simple to find the wire that turned on
the radio, and use it to turn on a relay.
...

I did this once with a "modern" digital alarm clock with a piezo beeper.
I just picked off the pulses to the beeper, and triggered a retriggerable
one-shot to turn on my large alarm, which was just a MVB and big speaker.
Actually, it was two MVBs, so I got a two-tone blare that really annoyed
the neighbors. ;-)
Geez! I never needed such noise to awaken! What the heck knocked you out
so hard? The ticking of a mechanical clock keeps me awake.
 
"js5895" <JoshTmp@nycap.rr.com> wrote in message
news:1112760564.180299.140220@g14g2000cwa.googlegroups.com...
Hi,

I'm studying electrical, what's the best way to remember the P.I.R.E.
wheel.
Learn just one formula such as V=IR and rearrange terms mathematically
as needed. No escaping the math if you want this field.
 
Lord Garth wrote:

I'm studying electrical, what's the best way to remember the
P.I.R.E. wheel.

Learn just one formula such as V=IR and rearrange terms mathematically
as needed. No escaping the math if you want this field.
Pedantic mode on. :)
You have to learn _two_ equations, actually.

V=I*R (Volt=Amp*Ohm)
P=U*I (Watt=Volt*Amp)

Then learn how to re-arrange these equations as needed for the problem
at hand, and use a calculator to get the result.

The art of re-arranging equations is called algebra, and you need some
basic knowledge and experience in this.


An alternative is to use a visual diagram like the ones I have put on a
web site

http://humanist.250free.com/

Click on the two .jpg files at the bottom of the list, save them to
hard disk. Can be distributed freely.


--
Roger J.
 
<dewdrops@2die4.com> wrote in message
news:1112763002.323979.24920@z14g2000cwz.googlegroups.com...
i hope somebody can help me. i bought a doerr pump at a garage sale the
other day. they guy tol dme it had never been used but tis a little
old. it has a strange plug almost looks like a 240 volt. but the pump
says that its 115v. i know very little about motors! when i connect it
to my outlet with some wires.. it makes a humming noise and starts to
heat up. the motor is defineitly not spinning. im pretty sure the pump
works, im just doing something wrong. any ideas? the following is on
the pump patent:3311293 insul class a 5.4 A 60HZ 1725 rpm 1/4 hp mod no
0522v103c(?)186 single phase mtr ref 50156aa733 fr h487. thanks for
your help!

The motor might have a bad start capacitor. However, you have not said
what type of motor is on the pump. The motor could be a universal type
or an inductive type. The universal type has brushes and a commutator ring.
That would be the type with a capacitor for startup.
 
<dewdrops@2die4.com> wrote in message
news:1112766603.662249.49500@g14g2000cwa.googlegroups.com...
thank you very much for the replys! im goign to go open up what i think
may be the capacitor casing. how can i tell if the capacitor is any
good? the only electrical meter i have is for measuring resistence. im
thinking the plug may be weird because of the motors age??? thanks again

If you can temporarily unload the motor, (so it need
not drive anything), power it up, give its shaft a good
spin by hand or wound rope to get it started, then, if
it runs fast without overheating, the chances are very
good that just replacing that starting cap will solve any
problem at the motor. It could be that it is stalling due
to congealed lubricant or something in the mechanism.
It would not hurt to get that rotating as freely as you can.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.
 
<dewdrops@2die4.com> wrote in message
news:1112767705.668848.249400@l41g2000cwc.googlegroups.com...
i took out what i think is the capacitor. it has two wires going into
it and one other place where a wire can be connected. the back of it
(opposite the wires) is open and there is a metal disk that has a screw
righ tin the middle (variable?). like i said i have no idea what im
talking about lol. im not seeing any units of capacitence or anything
really. it does say pat 2585704 & others. also says klixon and
mee26rx-368 each terminal is numberd 1-3 thanks for your help! id hate
to see an expensive pump (that i got for $20 :) ) go to waste!

I could not find that patent # at http://www.uspto.gov/ .

The middle screw is probably for mounting. There
should be some kind of marking for the capacitance.
(Or maybe not that long ago.) If you take the part
to an appliance repair place, and tell them it is for an
old 1/4 HP motor, they may be able to find another
starter cap that would work.

But before replacing it, (unless you want to just go
ahead and spend money), I would try the free-running
hand-start experiment. If the motor will not run under
those conditions, it needs more help than a new cap.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.
 
"Larry Brasfield" <donotspam_larry_brasfield@hotmail.com>
wrote in message news:shL4e.102$3n3.1230@news.uswest.net...
dewdrops@2die4.com> wrote in message
news:1112767705.668848.249400@l41g2000cwc.googlegroups.com...
i took out what i think is the capacitor. it has two wires going into
it and one other place where a wire can be connected. the back of it
(opposite the wires) is open and there is a metal disk that has a screw
righ tin the middle (variable?). like i said i have no idea what im
talking about lol. im not seeing any units of capacitence or anything
really. it does say pat 2585704 & others. also says klixon and
mee26rx-368 each terminal is numberd 1-3 thanks for your help! id hate
to see an expensive pump (that i got for $20 :) ) go to waste!


I could not find that patent # at http://www.uspto.gov/ .
Woops, wrong search function. That patent appears
to have been issued in 1952 for a thermostat device.
I'm guessing it is the motor's thermal cutout for when
the starting or main winding overheats.


The only real use of this info is that it dates the motor.
That starting cap is very likely dried out a half century
later. I would replace it without further ado.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.
 
In article <1112766603.662249.49500@g14g2000cwa.googlegroups.com>,
dewdrops@2die4.com wrote:

thank you very much for the replys! im goign to go open up what i think
may be the capacitor casing. how can i tell if the capacitor is any
good? the only electrical meter i have is for measuring resistence. im
thinking the plug may be weird because of the motors age??? thanks again
Please attempt to describe (or better yet, if you've got the gear to do
so, snap a good clear picture of it, jpeg it down to a reasonable size
and put it online someplace, then post a pointer to it here) the plug a
bit better than "weird"?

Two vertical blades? One vertical, one horizontal? Both horizontal?
Three blades in a roughly circular pattern? Two round pins? Four blades
in a circle? Two *LARGE* blades plus a largish round pin? One blade
vertical, the other blade an "L" shape, plus a round pin? Something else?

Knowing *EXACTLY* what the plug looks like *CAN* (unfortunately, not
"will") give a good idea of what kind of juice it wants, but describing
it as "weird" is just about as useful as a screen door on a submarine in
terms of figuring out what it expects to be fed.

And as a bit of advice: If you need to ask "How can I tell if a
capacitor is any good?", then quite frankly (and with apologies in
advance for what's probably going to sound like a slam or a putdown, but
isn't intended to be one) you aren't qualified to consider opening the
beast up, and you should make no attempt to do so unless you don't care
that you'll probably screw something up (possibly including yourself...
Electricity's "bite" is MUCH worse than its "bark") beyond repair.

You've already gone FAR beyond what I'd recommend for anyone with what
your level of expertise seems to be by dinking around trying to run it
from an wires jury-rigged to an incompatible socket. Hell, to lay it all
out there for everyone to see, you've already gone further than *I*
would have, and I'm far from being a beginner at the electricity and
electronics game. If you're lucky, you didn't damage it. If you're not,
you may well have "smoke-tested" it, and it's never going to run no
matter what you do. The very fact that you need to ask "how do I..."
says that you're tinkering with something you don't have the proper
knowledge to be messing around with without standing a very good chance
of trashing it.

As I said, this isn't intended as a slam or putdown - It's simple
statement of fact. The need to ask "how do I..." about such a basic
concept as determining whether a capacitor is good or bad is almost
always an indicator of someone who is "in way over his head". Don't
despair, though... Stupidity might be forever, but simple ignorance such
as you're displaying can be easily cured with a dose of edgyookayshun :)

Here's your first dose:
Set up your meter for high ohms - 20K or thereabouts should be fine.
Once you've gotten to the leads of the capacitor, use a screwdriver with
a well-imsulated handle to short the leads of the capacitor together.
Get yourself mentally prepared for a miniature lightning bolt to go off
when the screwdriver makes contact. Eyeball the capacitor - Does it have
a polarity marking? (Usually a plus or a minus sign, possibly a line of
them, situated near one of the leads) If so, observe polarity - red/plus
to plus, black/minus to either minus or the other lead from the
capacitor - and touch the probes to the capacitor lead. If the cap isn't
totally dead, you should see almost zero ohms at first, then rising to a
higher value.

If you see that, leave the probes in place for a few seconds, then
remove them, switch your meter to read volts (20 will probably be
overkill, but if you've got a higher range, start there, and work down
until you get a reading) and touch the probes to the capacitor leads
again. You should see an initial high value that slowly drops to zero.

If either of these tests doesn't do what I told you would happen, then
the cap is probably toast, and you'll need a new one. If they both work
as described, put the lid back on. It's at least acting as a capacitor
should, regardless of whether age has sent it "off value" or not, and it
probably isn't the source of your problem.

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.
 
"Don Bruder" <dakidd@sonic.net> wrote in message
news:vFL4e.13520$m31.133841@typhoon.sonic.net...
In article <1112766603.662249.49500@g14g2000cwa.googlegroups.com>,
dewdrops@2die4.com wrote:

thank you very much for the replys! im goign to go open up what i
think
may be the capacitor casing. how can i tell if the capacitor is any
good? the only electrical meter i have is for measuring resistence.
im
thinking the plug may be weird because of the motors age??? thanks
again


Please attempt to describe (or better yet, if you've got the gear to
do
so, snap a good clear picture of it, jpeg it down to a reasonable size
and put it online someplace, then post a pointer to it here) the plug
a
bit better than "weird"?

Two vertical blades? One vertical, one horizontal? Both horizontal?
Three blades in a roughly circular pattern? Two round pins? Four
blades
in a circle? Two *LARGE* blades plus a largish round pin? One blade
vertical, the other blade an "L" shape, plus a round pin? Something
else?

Knowing *EXACTLY* what the plug looks like *CAN* (unfortunately, not
"will") give a good idea of what kind of juice it wants, but
describing
it as "weird" is just about as useful as a screen door on a submarine
in
terms of figuring out what it expects to be fed.

And as a bit of advice: If you need to ask "How can I tell if a
capacitor is any good?", then quite frankly (and with apologies in
advance for what's probably going to sound like a slam or a putdown,
but
isn't intended to be one) you aren't qualified to consider opening the
beast up, and you should make no attempt to do so unless you don't
care
that you'll probably screw something up (possibly including
yourself...
Electricity's "bite" is MUCH worse than its "bark") beyond repair.

You've already gone FAR beyond what I'd recommend for anyone with what
your level of expertise seems to be by dinking around trying to run it
from an wires jury-rigged to an incompatible socket. Hell, to lay it
all
out there for everyone to see, you've already gone further than *I*
would have, and I'm far from being a beginner at the electricity and
electronics game. If you're lucky, you didn't damage it. If you're
not,
you may well have "smoke-tested" it, and it's never going to run no
matter what you do. The very fact that you need to ask "how do I..."
says that you're tinkering with something you don't have the proper
knowledge to be messing around with without standing a very good
chance
of trashing it.

As I said, this isn't intended as a slam or putdown - It's simple
statement of fact. The need to ask "how do I..." about such a basic
concept as determining whether a capacitor is good or bad is almost
always an indicator of someone who is "in way over his head". Don't
despair, though... Stupidity might be forever, but simple ignorance
such
as you're displaying can be easily cured with a dose of edgyookayshun
:)

Here's your first dose:
Set up your meter for high ohms - 20K or thereabouts should be fine.
Once you've gotten to the leads of the capacitor, use a screwdriver
with
a well-imsulated handle to short the leads of the capacitor together.
Get yourself mentally prepared for a miniature lightning bolt to go
off
when the screwdriver makes contact. Eyeball the capacitor - Does it
have
a polarity marking? (Usually a plus or a minus sign, possibly a line
of
them, situated near one of the leads) If so, observe polarity -
red/plus
to plus, black/minus to either minus or the other lead from the
capacitor - and touch the probes to the capacitor lead. If the cap
isn't
totally dead, you should see almost zero ohms at first, then rising to
a
higher value.

If you see that, leave the probes in place for a few seconds, then
remove them, switch your meter to read volts (20 will probably be
overkill, but if you've got a higher range, start there, and work down
until you get a reading) and touch the probes to the capacitor leads
again. You should see an initial high value that slowly drops to zero.

If either of these tests doesn't do what I told you would happen, then
the cap is probably toast, and you'll need a new one. If they both
work
as described, put the lid back on. It's at least acting as a capacitor
should, regardless of whether age has sent it "off value" or not, and
it
probably isn't the source of your problem.

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb.
21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password
in the
subject unless it comes from a "whitelisted" (pre-approved by me)
address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.
Don,
I am glad you said all that because I often get bagged for saying things
like "You do not know enough to do what you want" when I am trying to
save the OP from killing himself or others.
--
John G

Wot's Your Real Problem?
 
Tommi-Vogel@gmx.de (Thomas Vogel) wrote:

I want to construct a circuit which switch a relay by a alarm clock.
Know anyone where I can find a plan in the internet or in a book or in
a magazine?
Is it possible that the OP wants to use an old-fashioned mechanical
alarm clock as the source? If so, that gives me an excuse for some
nostalgic recollections <g>.

About 20 years ago, chatting to a friend in the office about our
shared habit of early rising, he mentioned that he had to wake his
deaf teenage daughter each morning. She too had to leave early for
work but because of her handicap couldn't use normal alarms like a
clock or radio. That got me exploring some electronic possibilities:

Light - simulating the sun beaming down onto her face. A bright
spotlamp perhaps, or an infra-red lamp of the sort sometimes fitted in
bathrooms. Quickly dismissed as I didn't know enough to be sure of its
safety over prolonged exposure. I did try a few experiments with
flashing a normal domestic 100W spotlamp a couple of feet away but
decided that couldn't be reliably expected to wake her up, even if she
happened to be facing directly towards it.

Breeze - a pleasant stream of air from a bedside fan. Experiment
quickly showed it would need to be a largish fan to have any chance.
But impossible to devise a reliable way of ensuring it stayed in
position, short of strapping it to her head!

Electric Shock - fleetingly toyed with the idea of a (battery
operated!) wrist strap, delivering a 40 or 50V. Really was fleeting
<g>.

Vibration - finally settled on this, and built a gadget which she used
successfully for many months.

A small d.c motor with a lead weight attached eccentrically vibrated
sufficiently when placed under the pillow. Used an old, cheap
mechanical alarm clock with a modification to the striker mechanism so
that it repeatedly opened and closed an electric contact.

The clock was mounted on top of a home made wooden box, and the
ultra-simple electronics on a piece of stripboard. A jack plug and
socket were used to connect the circuit's output signal to the motor
unit via a pair of wires about a metre long. An l.e.d in parallel with
the socket provided a supplementary indication, useful for testing.
Improvised electrical contacts by epoxy gluing a strip of tin inside
the casing, isolated electrically by the glue, so that the hammer
could strike it without hindrance. While the contacts were closed, a
brief positive pulse was delivered to the base of a darlington pair
arranged as an emitter follower. If the plug was in place, then the
motor vibrated. In any case the l.e.d would light. With 3 x 1.5V
D-type batteries, after allowing for the two base-emitter drops this
delivered a little under 3V to the motor. Quiescent current was
negligible, so no additional ON/OFF switch was necessary in practice.
The existing mechanical one on the clock served the purpose. The
motor was mounted in a small plastic case. Finished unit:

http://www.terrypin.dial.pipex.com/Images/DeafAlarm.jpg

I was pleased to hear that it performed very well in practice. But
about six months later it got dropped from a shelf, disintegrating
beyond repair. At least, that's what my friend told me!

--
Terry Pinnell
Hobbyist, West Sussex, UK
 
"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> wrote in message
news:6bh751pmrss0soi22e3ji1e6tt9qmgon6p@4ax.com...
Tommi-Vogel@gmx.de (Thomas Vogel) wrote:

I want to construct a circuit which switch a relay by a alarm clock.
Know anyone where I can find a plan in the internet or in a book or in
a magazine?

Is it possible that the OP wants to use an old-fashioned mechanical
alarm clock as the source? If so, that gives me an excuse for some
nostalgic recollections <g>.

About 20 years ago, chatting to a friend in the office about our
shared habit of early rising, he mentioned that he had to wake his
deaf teenage daughter each morning. She too had to leave early for
work but because of her handicap couldn't use normal alarms like a
clock or radio. That got me exploring some electronic possibilities:

Light - simulating the sun beaming down onto her face. A bright
spotlamp perhaps, or an infra-red lamp of the sort sometimes fitted in
bathrooms. Quickly dismissed as I didn't know enough to be sure of its
safety over prolonged exposure. I did try a few experiments with
flashing a normal domestic 100W spotlamp a couple of feet away but
decided that couldn't be reliably expected to wake her up, even if she
happened to be facing directly towards it.

Breeze - a pleasant stream of air from a bedside fan. Experiment
quickly showed it would need to be a largish fan to have any chance.
But impossible to devise a reliable way of ensuring it stayed in
position, short of strapping it to her head!

Electric Shock - fleetingly toyed with the idea of a (battery
operated!) wrist strap, delivering a 40 or 50V. Really was fleeting
g>.

Vibration - finally settled on this, and built a gadget which she used
successfully for many months.

A small d.c motor with a lead weight attached eccentrically vibrated
sufficiently when placed under the pillow. Used an old, cheap
mechanical alarm clock with a modification to the striker mechanism so
that it repeatedly opened and closed an electric contact.

The clock was mounted on top of a home made wooden box, and the
ultra-simple electronics on a piece of stripboard. A jack plug and
socket were used to connect the circuit's output signal to the motor
unit via a pair of wires about a metre long. An l.e.d in parallel with
the socket provided a supplementary indication, useful for testing.
Improvised electrical contacts by epoxy gluing a strip of tin inside
the casing, isolated electrically by the glue, so that the hammer
could strike it without hindrance. While the contacts were closed, a
brief positive pulse was delivered to the base of a darlington pair
arranged as an emitter follower. If the plug was in place, then the
motor vibrated. In any case the l.e.d would light. With 3 x 1.5V
D-type batteries, after allowing for the two base-emitter drops this
delivered a little under 3V to the motor. Quiescent current was
negligible, so no additional ON/OFF switch was necessary in practice.
The existing mechanical one on the clock served the purpose. The
motor was mounted in a small plastic case. Finished unit:

http://www.terrypin.dial.pipex.com/Images/DeafAlarm.jpg

I was pleased to hear that it performed very well in practice. But
about six months later it got dropped from a shelf, disintegrating
beyond repair. At least, that's what my friend told me!
I think he was a troll Terry, there has been no return of the OP to the
group for any clairification.

I had a deaf person sleeping on my couch one weekend, she
slept so soundly that even a wet cloth on her face did not rouse her.
I hope she never has to contend with a fire. BTW, I'm told that her
dog would lick her hand at the sound of the alarm to awaken her
however the dog was not here. Using animals to wake her is about
the best solution I could imagine.


solution
 
"Michael Redmann" <redmann@despammed.com> wrote in message
news:d30a6c$7m9$04$1@news.t-online.com...
PeteS schrieb:

Let's do the actual mathematics :)

Assume we charge a 10uF and 1uF to 10V. The 10uF will have 100uC
(Q=CV) and the 1uF 10uC of charge. The total charge is 110uC.
Now lets stick them in series.
The first thing is to calculate the new effective capacitance =
C1*C2/(C1 + C2) = 0.909uF. A thing about series caps is the total
capacitance is always less than the smallest cap.

As Q = CV, then V = Q/C so 110uC/0.909uF = 121V (near enough).

Hi Pete

I did it by calculating the total energy stored in both capacitors which
is 5.5 mJ. The corresponding voltage with both caps in series is V = V0
* (C1+C2)/sqrt(C1*C2) after charging each cap to V0.

So, what's correct? Conservation of charge or energy?

Let's test your calculation with two equal capacitors, say 10 uF at 10
volts. If you were right voltage would be 200 uC/5 uF = 40 V ! That's
obviously wrong. Of course the correct answer is 20 V. That's the same
voltage you get using my formula.

Regards
--
Michael Redmann
"It's life, Jim, but not as we know it." (Spock)
If the method is:

1) Place two paralled caps, of different values, across a voltage source (of
magnitude V)
2) Remove the voltage source
3) Separate the caps and reconnect them in series
4) Measure the voltage across the series combination

It doesn't make sense that the series voltage would be anything other than
2*V. How can the voltage across either of the caps suddenly increase when
you separate them?

Also, I tried it. I used a 220uF cap and a 2200uF cap. The supply was 5V.
After I separated them, and then place them in series, I measured 10V across
the series combination.

Was this the method described for the so-called parametric amplifier? I did
a little searching on this subject, but never found this method described
for parametric amplifiers.

???

Bob
 

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