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Need a simple nightlight circuit ...

E

Edward Clapper

Jan 1, 1970
0
All,

I'm a non-EE designer and need to show a nightlight prototype for
demonstration.

I have a single-cell AAA attached to a mini-Maglite replacement bulb
(designed for this battery size), and it is plenty bright. Of course, I
can add a manual switch.

Can anyone suggest the simplest circuit that would provide automatic on/off
based on lighting intensity? I think I need a photocell or photodiode, but
beyond that I'm clueless. Obviously it would be nice to adjust the
sensitivity using a small pot in the circuit. Also, it's desireable to
keep the AAA single-cell battery configuration if at all possible.

Hope someone can help!

Thanks,

Ed Clapper
 
I

Ian Stirling

Jan 1, 1970
0
Edward Clapper said:
All,

I'm a non-EE designer and need to show a nightlight prototype for
demonstration.

I have a single-cell AAA attached to a mini-Maglite replacement bulb
(designed for this battery size), and it is plenty bright. Of course, I
can add a manual switch.

You do know that the life of this bulb is probably under 20 hours?
 
F

Frank Bemelman

Jan 1, 1970
0
Edward Clapper said:
All,

I'm a non-EE designer and need to show a nightlight prototype for
demonstration.

I have a single-cell AAA attached to a mini-Maglite replacement bulb
(designed for this battery size), and it is plenty bright. Of course, I
can add a manual switch.

Can anyone suggest the simplest circuit that would provide automatic on/off
based on lighting intensity? I think I need a photocell or photodiode, but
beyond that I'm clueless. Obviously it would be nice to adjust the
sensitivity using a small pot in the circuit. Also, it's desireable to
keep the AAA single-cell battery configuration if at all possible.

Who wants a nightlight running on a single AAA battery. It will
only last one or perhaps two nights, and then your battery is
flat.

Nightlights should run on mains power. For a demo, you can
just tell it will turn on when it gets dark. If that is
not convincing enough, buy one cheap and rip the internals.
 
W

Walter Harley

Jan 1, 1970
0
Edward Clapper said:
All,

I'm a non-EE designer and need to show a nightlight prototype for
demonstration.

I have a single-cell AAA attached to a mini-Maglite replacement bulb
(designed for this battery size), and it is plenty bright. Of course, I
can add a manual switch.

Can anyone suggest the simplest circuit that would provide automatic on/off
based on lighting intensity? I think I need a photocell or photodiode, but
beyond that I'm clueless. Obviously it would be nice to adjust the
sensitivity using a small pot in the circuit. Also, it's desireable to
keep the AAA single-cell battery configuration if at all possible.


I'm assuming that battery life is not a problem, as others alluded; that
this is just a concept demo, or maybe part of something else.

In general, photosensitive devices (like photocells) turn themselves 'on'
when they see light. So, you need something to invert that logic: when the
photocell turns on, the light turns off. Second, you need to make sure that
the photocell can't "see" the light it's controlling: otherwise, when it
gets dark it will turn on the light, which will make it think it's light
again, so it will turn off the light, and so forth. You don't want that.
Finally, you want "hysteresis" - you want it so that the threshold to turn
"on" is a bit darker than the threshold to turn "off", so that when it's
dusk, it doesn't flicker.

Off the cuff, I think the untested circuit below will do that for you.
Transistors are not critical, any NPN (for the 2n2222) and PNP (for the
2n2907) will do just fine. Depending on the photocell you find, the
resistor values might not be quite right. I'll go try it out soon as I get
a chance...

.-------o-----o------------.
| | | |
| .---o | | LAMP
| | | | .-.
| | .-. | 2n2907 ( X )
| '->| | | '-'
| 25k | | >| ___ |
| '-' |- -|___|--o
| | /| 10k |
| | | |
1.5v | | | |
--- .-. .-. |
- | | | |100k |
| | | | | |
| 1k'-' '-' |
| | | |
| | | |/
| o-----o----------| 2n2222
| | |>
| | |
| .-. |
| | | cadmium sulfide |
| | | (CdS) photocell |
| '-' |
| | |
| | |
'-------o------------------'
created by Andy´s ASCII-Circuit v1.22.310103 Beta www.tech-chat.de
 
S

Seth Koster

Jan 1, 1970
0
I have a single-cell AAA attached to a mini-Maglite replacement bulb
(designed for this battery size), and it is plenty bright. Of course, I
can add a manual switch.

Is this for camping or something (why battery?)? Do you really
want it that bright (or need it to be)? An LED or LED cluster should
draw less power (depending on how many LEDs), but 1.5V is going to be
tough. Keep in mind that maglights are not really meant to be
running all night every night.
Can anyone suggest the simplest circuit that would provide automatic on/off
based on lighting intensity? I think I need a photocell or photodiode, but
beyond that I'm clueless. Obviously it would be nice to adjust the
sensitivity using a small pot in the circuit. Also, it's desireable to
keep the AAA single-cell battery configuration if at all possible.

You could hang a photodiode off the base of a transistor going to
ground creating a high impedance and letting the transistor turn on,
then when the diode turns on (has light shining on it) it would drain
the current to ground. I threw an LED in as the nightlight source,
the resistors will depend on your voltage but I doubt 1.5V is going to
be enough to run the solid state here. You'll drop around 1.4V over
the LED alone, depending on the LED, and about another .7 over the
transistor. If you use mains (as suggested by others), you could use
a relay coil and freewheeling diode to switch power to a lightbulb in
place of the resistor and LED. IF YOU USE MAINS BE CAREFUL!!!
Don't play with mains wiring if you dont know what you are doing,
people die every year due to inability combined with disproportional
self-confidence (with all sorts of stuff, from cars to electricity).
Thats about as simple as it gets, I guess.




VCC
+
|
o--------o
| |
| /
\ \
/ /
\ |
/ V LED
| -
| |
| |/
o------|
| |\
| * NPN
| |
- |
PHOTODIODE ^ |
| |
| |
=== ===
GND GND
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de
 
E

Edward Clapper

Jan 1, 1970
0
Actually, there are reasons to prefer a battery-powered nightlight beyond
a simple concept demo if it's possible.

How about those landscaping lights that collect solar energy all day and
run all night without needing traditional batteries or wired power?

Ignoring expense, etc. what would the circuit look like if it had to
drive 2-3 white LED's (assumed for better power-to-light efficiency), and
used a solar cell to collect energy during the day? The assumption would
be that the light collected would be internal incandescent or flourescent
rather than sunlight (again thinking of it as a night light). The basic
goal is to provide a nightlight function without requiring mains power
(mostly for safety reasons).

The help so far has been greatly appreciated.

Ed Clapper
 
T

Terry Pinnell

Jan 1, 1970
0
Walter Harley said:
Off the cuff, I think the untested circuit below will do that for you.

<snip>

Here's how it looks when simulated with CircuitMaker:

http://www.terrypin.dial.pipex.com/Images/NightLight2.gif

Apart from being a little slow to switch on, looks good to me.
Surprising for such a low supply voltage! (OK at 1.24V, failed at
1.23V.)

Also posted in alt.binaries.schematics.electronic.
 
F

Frank Bemelman

Jan 1, 1970
0
Edward Clapper said:
Actually, there are reasons to prefer a battery-powered nightlight beyond
a simple concept demo if it's possible.

How about those landscaping lights that collect solar energy all day and
run all night without needing traditional batteries or wired power?

Ignoring expense, etc. what would the circuit look like if it had to
drive 2-3 white LED's (assumed for better power-to-light efficiency), and
used a solar cell to collect energy during the day? The assumption would
be that the light collected would be internal incandescent or flourescent
rather than sunlight (again thinking of it as a night light). The basic
goal is to provide a nightlight function without requiring mains power
(mostly for safety reasons).

Those (cheap) garden lights with solar panels only work because they
are placed outside and enjoy the powerful sunshine. On cloudy days
or in wintertime their performance is terrible, close to nothing at all.

Indoors, the light is even less. You would need a very large solar
panel.

Perhaps a tritium light source is better for your indoor nightlight.
http://www.angelfire.com/electronic/cwillis/rad/tlight.html

Light with no battery, no solar panel, 24hrs a day. It will
only light up your gadget, not the room ;)
 
F

Fred Bloggs

Jan 1, 1970
0
Edward said:
Ignoring expense, etc. what would the circuit look like if it had to
drive 2-3 white LED's (assumed for better power-to-light efficiency), and
used a solar cell to collect energy during the day?

Send $500 to the SED international account- and we MAY do a preliminary
evaluation- otherwise bug off.
 
E

Edward Clapper

Jan 1, 1970
0
You may bug off, yourself. I don't think that my request deserves your
tone, and I certainly would not pursue any endeavor with someone who
represents themselves the way that you do. What an introduction!
 
T

Terry Pinnell

Jan 1, 1970
0
Terry Pinnell said:
<snip>

Here's how it looks when simulated with CircuitMaker:

http://www.terrypin.dial.pipex.com/Images/NightLight2.gif

Apart from being a little slow to switch on, looks good to me.
Surprising for such a low supply voltage! (OK at 1.24V, failed at
1.23V.)

Also posted in alt.binaries.schematics.electronic.

Walter: Over in alt.binaries.schematics.electronic, Win Hill pointed
out that hysteresis was too high. I suggest that increasing R2 could
fix that; 10k for example gives much lower H.
 
R

Roger Gt

Jan 1, 1970
0
X-No-Archive: yes
"Edward Clapper" wrote insultingly
: You may bug off, yourself. I don't think that my request
deserves your
: tone, and I certainly would not pursue any endeavor with someone
who
: represents themselves the way that you do. What an
introduction!
:
: Fred Bloggs wrote
: > Edward Clapper wrote:
: >> Ignoring expense, etc. what would the circuit look like if
it had to
: >> drive 2-3 white LED's (assumed for better power-to-light
efficiency),
: >> and used a solar cell to collect energy during the day?
: >
: > Send $500 to the SED international account- and we MAY do a
: > preliminary evaluation- otherwise bug off.

The guy offered to do a complex evaluation pretty cheaply, a real
bargain.

However I CAN give you the free version.

It would be dark lines on a white page which represent circuit
elements used to perform the desired function. At a cost of about
$500 from some contractors, and about $12,000 from me since I
would also do a complete evaluation of the components for
suitability and predict life expectancy in the expected service!
I also do testing over temperature and any safety compliance
testing is included!

See? No charge!
Is my tone and better? Light tan I think!
 
E

Edward Clapper

Jan 1, 1970
0
The guy offered to do a complex evaluation pretty cheaply, a real

He agreed to do nothing of the sort; he told me to send $500 to get his
attention, and then arrogantly stated that he MAY take a look at it. As
a degreed engineering professional with 15 years of experience, I can
tell you that his response was nowhere near professional in nature. If
you think that it is, I would have to wonder about your credibility.
However, I was not looking for a service.

Often on a newsgroup of this sort, people share basic circuits that they
have built or devised for no charge at all. I was looking for a short-
cut of this sort, and have no problem admitting that I was looking to get
something for free. There are, in fact, several such schematics freely
available on the internet, and in books on my shelf. I was looking to
see what this community had to offer.

As for the complexities of an actual nightlight product as discussed,
that certainly requires engineering. I would expect that an engineer
would be required to develop such a product, and that it would cost money
to do so. My interest in pursuing that level was mainly philosophical
and educational. I will not be productizing this device myself, and if
the people I demo to decide to do so, I guarantee that they will work
with a design service selected for their competency and not their
arrogance and rudeness.
Is my tone and better? Light tan I think!

Yes, your tone is better, certainly. However, again I'm not looking for
a design service. I can cobble what I need together with what I already
know. Thanks anyway.

Regards,

Ed Clapper
 
R

Roger Gt

Jan 1, 1970
0
X-No-Archive: yes
"Edward Clapper" wrote
: > The guy offered to do a complex evaluation pretty cheaply, a
real
: > bargain.
:
: He agreed to do nothing of the sort; he told me to send $500 to
get his
: attention, and then arrogantly stated that he MAY take a look at
it. As
: a degreed engineering professional with 15 years of experience,
I can
: tell you that his response was nowhere near professional in
nature. If
: you think that it is, I would have to wonder about your
credibility.
: However, I was not looking for a service.

So you were only looking for a freebie and really didn't need it?
Hum_ Err_ Okay! BTW: Getting my attention is also sending money!

I agree that his response was rather curt, it could easily be
misinterpreted.
Questions about my credibility are moot. I only have 40 years
experience and no ego about my skills, but I do charge for my
services. Feel free to think anything you like, it has no effect
on anything at all.

I have yet to encounter anyone on this or any news list who is not
"arrogant" Indeed it is the norm! Manners are also lacking and in
some cases non-existent.
The nature of the Beast!

: Often on a newsgroup of this sort, people share basic circuits
that they
: have built or devised for no charge at all. I was looking for a
short-
: cut of this sort, and have no problem admitting that I was
looking to get
: something for free. There are, in fact, several such schematics
freely
: available on the internet, and in books on my shelf. I was
looking to
: see what this community had to offer.
:
: As for the complexities of an actual nightlight product as
discussed,
: that certainly requires engineering. I would expect that an
engineer
: would be required to develop such a product, and that it would
cost money
: to do so. My interest in pursuing that level was mainly
philosophical
: and educational. I will not be productizing this device myself,
and if
: the people I demo to decide to do so, I guarantee that they will
work
: with a design service selected for their competency and not
their
: arrogance and rudeness.

You just said you are an engineer, so you don't think this is
worth YOUR effort? I don't get it. If you didn't need anything,
why ask? (Rhetorical, you have already said.)

: > Is my tone and better? Light tan I think!
:
: Yes, your tone is better, certainly. However, again I'm not
looking for
: a design service. I can cobble what I need together with what I
already
: know. Thanks anyway.
: Regards, Ed Clapper

"Cobble" is a good word But I wouldn't use it, it's not a
customary description used by an engineering professional.

Sorry I butted in. Clearly my input was unneeded! Bye
 
F

Fred Bloggs

Jan 1, 1970
0
Edward said:
You may bug off, yourself. I don't think that my request deserves your
tone, and I certainly would not pursue any endeavor with someone who
represents themselves the way that you do. What an introduction!

Like I give a flying F.....K about any goddammed impressions or any of
this other riffraff oriented social formalisms of the mediocre? This
newsgroup is about hobbyists, students, and recreation, it's not about
providing a free lunch to a "productizer."
 
W

Walter Harley

Jan 1, 1970
0
Edward Clapper said:
You may bug off, yourself. I don't think that my request deserves your
tone, and I certainly would not pursue any endeavor with someone who
represents themselves the way that you do. What an introduction!

When posting to a newsgroup, it often soothes one's emotions to first read
the responses of regular posters to other questions. You'll discover that
some folks are habitually unpleasant. You have the choice of whether to
attend to their responses, or to teach your newsreader not to show them.
Sometimes these people are knowledgeable, so hiding their responses means
you may miss valuable information, but you also avoid unnecessary
irritation. Fred is in this category. There is no point in taking his
responses personally, as history demonstrates they are not personal.
 
W

Walter Harley

Jan 1, 1970
0
Edward Clapper said:
Actually, there are reasons to prefer a battery-powered nightlight beyond
a simple concept demo if it's possible.

How about those landscaping lights that collect solar energy all day and
run all night without needing traditional batteries or wired power?

Ignoring expense, etc. what would the circuit look like if it had to
drive 2-3 white LED's (assumed for better power-to-light efficiency), and
used a solar cell to collect energy during the day? The assumption would
be that the light collected would be internal incandescent or flourescent
rather than sunlight (again thinking of it as a night light). The basic
goal is to provide a nightlight function without requiring mains power
(mostly for safety reasons).

The circuit would look quite radically different. For that matter, my
original circuit would look rather different if I were designing it for use
beyond a demo - I thought, based on your original post, you just needed
something quick-and-dirty.

But as I gather Fred Bloggs also responded, at that point, you're asking for
some real design work, and for that I charge money unless I'm feeling
awfully bored :)
 
R

Roger Gt

Jan 1, 1970
0
X-No-Archive: yes
"Fred Bloggs" wrote
: Edward Clapper wrote:
: > You may bug off, yourself.
: > I don't think that my request deserves your
: > tone, and I certainly would not pursue any
: > endeavor with someone who represents themselves
: > the way that you do. What an introduction!
:
: Like I give a flying F.....K about any goddammed impressions or
any of
: this other riffraff oriented social formalisms of the mediocre?
This
: newsgroup is about hobbyists, students, and recreation, it's not
about
: providing a free lunch to a "productizer."

Your right of course. Of course I thought it had something to do
with electronics, My BAD!!!!
 
E

Edward Clapper

Jan 1, 1970
0
Thanks, Walter. That is solid advice. Also, thank you for your posting
regarding my request.

You'll
 
E

Edward Clapper

Jan 1, 1970
0
snipped
The circuit would look quite radically different. For that matter, my
original circuit would look rather different if I were designing it
for use beyond a demo - I thought, based on your original post, you
just needed something quick-and-dirty.

The goal was ALWAYS for demo only. However, I asked the more advanced
design questions for my own education. Regardless of what circuit I used
in a demo, it would not be used in a product - even if I had paid someone
to design it. I'm showing an idea, and the nightlight function is just a
demonstration mechanism. However, if it's catchy enough it would be nice
to have some basic knowledge about feasibility.
But as I gather Fred Bloggs also responded, at that point, you're
asking for some real design work, and for that I charge money unless
I'm feeling awfully bored :)

Hopefully my response above and in other postings has clarified my
situation. Thanks again for your posts.
 
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