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Switch on a light box for 45 seconds

I work at a museum and would like to hook-up a light box to some kind
of switch that would have the box stay on for about 45 seconds and go
off. Any ideas?
Thanks
 
I work at a museum and would like to hook-up a light box to some kind
of switch that would have the box stay on for about 45 seconds and go
off. Any ideas?

I am assuming you want it to work like this: the user pushes a button,
the light box comes on, stays lit for 45 seconds, then turns off until
the user pushes the button again. I am also assuming that the light box
operates on regular wall-socket voltage from a regular wall socket, and
that you have someplace to put the control circuit.

If the above is true, then what you probably want is a "delay on break"
or "delay on release" relay. This is a relay (an electrically operated
switch) with an internal timer. There is a knob on top of the relay
that sets the time it stays on. These relays are usually designed to
plug into a standard socket, so you'd need to get a socket as well. You
also want to make sure you can get one that can be triggered by an
external (pushbutton) switch. You'll probably want to use a fairly
beefy pushbutton (like the ones used on arcade games) so it will last.

At the local electronics distributor, I can get a suitable relay and
socket for about US$65. Add another US$20 or so for a pushbutton, wire,
etc. The relay and socket will fit in a 3" (75 mm) cube. You'll have
a plug, a cord, the relay socket, the wiring to the light box, and the
wiring to the pushbutton.

If you're not familiar with wiring up things that plug into the wall,
get someone that is to help you with it. It's not that hard to do, but
the consequences of getting it wrong can be severe.

Matt Roberds
 
D

Dan Mills

Jan 1, 1970
0
I work at a museum and would like to hook-up a light box to some kind
of switch that would have the box stay on for about 45 seconds and go
off. Any ideas?
Thanks

Over here you can get light switches that do exactly this (intended for use
on staircases) maybe possible?

The other thought I have is that a photographic enlarger timer does what you
need.

Regards, Dan.
 
D

Dennis Mchenney

Jan 1, 1970
0
Might also look into using a motion detector wall switch, aimed as would
need to wave hand in a space to activate it. Not sure if can get one
with the exact time period you want or be adjustable to that.
 
C

Chris

Jan 1, 1970
0
I work at a museum and would like to hook-up a light box to some kind
of switch that would have the box stay on for about 45 seconds and go
off. Any ideas?
Thanks

If you'd like a store bought solution, stop by a camera store and look
at their darkroom timers. Gra-Lab is a good source for this in the
States.

If you'd like something a little less expensive, get a 12VDC wall wart
and the Velleman MK-111 Interval Timer kit. It uses a 555 and a relay
to give you exactly what you need. It includes circuit board and all
components except the wall wart. The relay will switch up to 3 amps at
120VAC.

Questions of this type usually receive a better response on
sci.electronics.basics.

Good luck
Chris
 
A

Alan Turner

Jan 1, 1970
0
I work at a museum and would like to hook-up a light box to some kind
of switch that would have the box stay on for about 45 seconds and go
off. Any ideas?
Thanks

I'd go to a hardware store and ask for one of those timers which runs a
bathroom extractor fan for a fixed period after the light is turned off.

An off-the-shelf solution will almost certainly be cheaper than a
homebuilt one once you factor in the cost of putting it in a box,
providing a power supply for the electronics, etc.

Alan
 
T

Terry Pinnell

Jan 1, 1970
0
I work at a museum and would like to hook-up a light box to some kind
of switch that would have the box stay on for about 45 seconds and go
off. Any ideas?
Thanks

It's not clear which of these you want:

a) a ready-made, shop-bought circuit just requiring careful
connection (by someone qualified, possibly yourself, as presumably the
box is mains-powered)

b) a circuit you can build

If the former, then you've had several recommendations.

If the latter, then you could base it on these circuits:
http://www.terrypin.dial.pipex.com/Images/555MonoByPU.gif
http://www.terrypin.dial.pipex.com/Images/555OneShot.gif
http://www.terrypin.dial.pipex.com/Images/555Mono+Driver.gif

with suitable Rt and Ct. For example, combinations such as
500k 82uF; 1M 39uF; 2.7M 15uF etc
give the required delay.

You haven't specified power supplies, or switch type, so adapt as
necessary.
 
K

Kim Sleep

Jan 1, 1970
0
A1 electronics in Toronto sells a 555 timer kit that will do what you need,
with all components, circuit board etc, for $11.00, and a enclosure for
another $4.00. It is adjustable from seconds to hours with a on-board pot.
All prices are Canadian $, and you can find them on the web.
 
F

Fred Bloggs

Jan 1, 1970
0
I work at a museum and would like to hook-up a light box to some kind
of switch that would have the box stay on for about 45 seconds and go
off.

This is a straight forward application of a timer relay. Press the
momentary switch, the relay applies power to the load for 45 seconds and
then removes power- regardless of the state of momentary switch after
the initial press. If you want the momentary switch to override the
time-out, then jumper terminal 8 to 2. This will cause the power to be
removed at the later of switch release or the 45 second time-out. There
are so-called OFF-(MOM)-ON type switches where the push action can make
it either momentary or permanently on which may be useful for that mode.
If this is for a viewer activated display, then you would not want this
mode of operation- do not jumper 8-2. Mate the line feed solid copper to
stranded 14ga type to make the 0.25" crimp terminal connections- do this
with wire nuts. All of this can mount in a standard wall mount switch
box. Avoid any web based so-called electronic projects or hobby type crap.

View in a fixed-width font such as Courier.





NEMA ENCLOSURE
+------------------------------------------------------+
| |
NTRL |(WHITE)
--(WHITE)------------------X-------------------------------|--->
| | to lamp
| | +---|--->
| | --------------- | |(BLACK)
| | / /| | |
LINE | +----HRDS4XX----+ | | |
--(BLACK)------X-----------|----------------+ | | | |
| | | | | | | | |
| | +--------|---------+ | | | | |
| | | | | _|_ _|_ | | | |
| | | | | 8 1 | | | |
| +-----------+ | | | | | |
| | | | | +-------|3 2|-------X |
| | | | | | | | |
| | |o | | | | | |
| | --| | | | | | |
| | |o | | | |4 | | |
| | | | | | screw | | |
| | +--+ | | O | | |
| | | | 5 | | |
| +-----------+ | KNOB __ | | |
| momentary | | | |
| sw +---------------+/ |
| |
| ~ 3 x 2 x 1.5 inch |
+------------------------------------------------------+

X= wire nut junction

See: http://www.ssac.com/catalog/HRDS1A01.pdf
 
F

Fred Bloggs

Jan 1, 1970
0
Chris said:
If you'd like a store bought solution, stop by a camera store and look
at their darkroom timers. Gra-Lab is a good source for this in the
States.

If you'd like something a little less expensive,...

I'll say- all that GraLab stuff is over-priced glitz, even a foot switch
is $60- any kind of electronic timer $200.
 
F

Fred Bloggs

Jan 1, 1970
0
Alan said:
I'd go to a hardware store and ask for one of those timers which runs a
bathroom extractor fan for a fixed period after the light is turned off.

An off-the-shelf solution will almost certainly be cheaper than a
homebuilt one once you factor in the cost of putting it in a box,
providing a power supply for the electronics, etc.

I don't like that suggestion and I'll tell you why: you go buy that
retail trash and what you end up with is an inferior imported knock-off
product cashing in on the reputation of the American made product at the
high price- plus the timing interval on those is in the 5-10 minute range.
 
S

Spehro Pefhany

Jan 1, 1970
0
I'll say- all that GraLab stuff is over-priced glitz, even a foot switch
is $60- any kind of electronic timer $200.

They're probably only making 10% of the quantity per year that they
used to make. Maybe less with all the used stuff floating around.


Best regards,
Spehro Pefhany
 
R

Rich Grise

Jan 1, 1970
0
I'll say- all that GraLab stuff is over-priced glitz, even a foot switch
is $60- any kind of electronic timer $200.

They're probably only making 10% of the quantity per year that they
used to make. Maybe less with all the used stuff floating around.[/QUOTE]

There are a couple of Gra-Lab timers on ebay right now for about $25.00.

Problem is, you'd have to preset it to 45 every time.

Actually, Fred Bloggs's suggestion looks reasonable.

Cheers!
Rich
 
K

Ken Moffett

Jan 1, 1970
0
I am assuming you want it to work like this: the user pushes a button,
the light box comes on, stays lit for 45 seconds, then turns off until
the user pushes the button again. I am also assuming that the light box
operates on regular wall-socket voltage from a regular wall socket, and
that you have someplace to put the control circuit.

If the above is true, then what you probably want is a "delay on break"
or "delay on release" relay. This is a relay (an electrically operated
switch) with an internal timer. There is a knob on top of the relay
that sets the time it stays on. These relays are usually designed to
plug into a standard socket, so you'd need to get a socket as well. You
also want to make sure you can get one that can be triggered by an
external (pushbutton) switch. You'll probably want to use a fairly
beefy pushbutton (like the ones used on arcade games) so it will last.

At the local electronics distributor, I can get a suitable relay and
socket for about US$65. Add another US$20 or so for a pushbutton, wire,
etc. The relay and socket will fit in a 3" (75 mm) cube. You'll have
a plug, a cord, the relay socket, the wiring to the light box, and the
wiring to the pushbutton.

If you're not familiar with wiring up things that plug into the wall,
get someone that is to help you with it. It's not that hard to do, but
the consequences of getting it wrong can be severe.

Matt Roberds


If yoe are interested in an off the shelf solution look at:
http://www.cowlacious.com/TimerProd.htm
 
K

Keith Wootten

Jan 1, 1970
0
In message said:
I work at a museum and would like to hook-up a light box to some kind
of switch that would have the box stay on for about 45 seconds and go
off. Any ideas?
Thanks
Rswww.com part number 490-194 for example.

Cheers
 
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