I need to keep a labtop in a unheated shed. The labtop spec says that it should not be used below 55 deg F. I would like to make a box with a heater to control the temperature. The shed is enclosed so that I have no problem with moisture(rain or snow).
Two problems. I have attempted to find thermostat switches between 60 and 80 deg F with no luck. Do they just not make them? Also I am being buried in information about heaters. Can someone provide a recommendation about a flat heater(1 or 2 inches thick) that I can use? Preferably surplus.
There are heater pads available to go in the bottoms of seed trays, I think. I'm sure my brother-in-law who's a bit of a horticulturalist, uses them. Another very simple alternative, is to just screw a few ten watt aluminium-clad resistors to a piece of ally or steel plate. Calculate the values so that with them all in series, they will dissipate about five or six watts, when feeding them with whatever low voltage you have available. 5 x 4R7 with a 12v supply should do it. PSU should be rated about double, so say 1 amp. I doubt that you would even need to worry about a thermostat, but if you did, surely a standard room stat covers the temperature range that you are looking for ? Another even *simpler* scheme might be to just put a couple of car interior light festoon bulbs in the box. Amazing just how much heat they can generate.
Remember that the laptop itself generates some heat - put it in an insulated box (styrofoam drink coolers are cheap) with a thermometer and see where the temperature stabilizes. You may not need any additional heating.
If additonal heating is needed, then you could use a 25 watt light bulb (or a heating pad). The thermostat may require some construction. You could use a standard wall thermostat (under $20US at hardware/home supply stores) with a relay and a transformer that supplies the voltage needed by the relay (12 and 24 volt transformers and relays are available in surplus - check
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Power the relay through the thermostat contacts and you'll have an adjustable temperature-controlled enclosure.
I used the wall thermostat + relay setup to control a 1500 watt heater in a workshop for years.
With current technology, I would use a DS18B20 temperature sensor and a PICAXE 08M microcontroller to control a solid state relay that controlled the heater. (Similar to this fan controller:
Make a sub enclosure for it. Hook up an surplus external CRT monitor to the laptop. The heat from the CRT should keep it warm if its in a separate enclosure. As far as that goes a old 13" tv would work too, and have entertainment to boot!
Or you can find a mechanical furnace thermostat. Get a 24 volt low voltage transformer and have it switch a relay to turn on a string of
25 watt lamps for a heater.
Don't try to heat the whole shed. Just heat a sub enclosure.
Bob
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You have me there. I have not measured the temperature inside the labtop. It has gotten down to 20 deg F so far this winter. The floppy died and that is what got me looking at the spec. I find it hard to believe just the electronics will keep it warm enough. It feels pretty cold. I stopped using it in the shed when the floppy died.
Think I will experiment with a bulb in a cardboard box and see if that will do it.
A light bulb in a cardboard box! I can't believe I though this was as hard as I made it. Half the people around here use bulbs in thier cisterns. Got my solution. I will run a box and a thermomiter and make sure it stays up where I need it. Thanks.
Check out pet stores or agricultural supply places for heaters - they make indoor/outdoor fiberglass enclosed pads for warming animals with built in thermostats. Dogs Cats Hogs, etc..
Likewise pet stores for terrarium heaters - indoor thingee that goes under the terrarium - usually no real thermostat but might have different power settings.
Thermostats are readily available through surplus outlets - easy to build from scratch too.
Hardware stores sell electric thermostats for electric baseboard heating. Designed to go in a standard switch box and with a positive action switch designed to switch 20 amps at 240 volts. Temperature range on the dial of the ones I have is 50-90 (F) but the actual knob travel is more like 30-100 (F). That, an insulated box and light bulb . .. .
The lower temp limit is usually because the lubricant in the hard drive can thicken and cause the platter to spin up slowly causing a head crash on boot up - worst case. Once running and warm it may be safe enough in a cold room as long as the drive stays up. Other downside is some liquid crystal displays are sluggish at low temps. Cold cathode fluorescent lamps may not fire cold - but not catastrophic failures as a rule.
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Turn the laptop on, let it boot. Close the lid to almost clicked shut. Don't click it shut if you have it set to go into suspend or hibernate on a lid close. Drink a cup of coffee.
Everything should be warmed up by then and the backlight will keep it warm enough.
There's nothing that'll be harmed at 50 degrees. The LCD will be a little slow, that's all. Things don't get interesting till you're below freezing.
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