Sidetracked by the temperature

[Lenp]

I was involved in an outdoor testing project last week that required me to run a shop power supply from an inverter in the middle of nowhere.
The power supply is a old and primitive variable DC unit with almost army tank reliability that has almost as much age as I have.
Once the setup was connected, the power supply neon indicator did not come on, and there was no output on the meters. It was confirmed that the inverter was on line so the problem was in the power supply. Since it was about 15 degrees outside, I ran an extension cord from the inverter to my vehicle where It was a bit warmer and I could look into the power supply issues. After opening the case, I noticed the neon indicator was now on, but still no voltage on the meter.

Long story made short, when the power supply was cold, the gas pressure in the indicator changed and it would not fire. As for the voltage, there is a press to reset circuit breaker on the power supply's output. It must have been depressed when it was cold and it just didn't pop back out. Maybe some lubricant thickened, plastic changed shape, whatever. It popped out by itself a little later and all was well.

Len

[Robert Reed]

In the span of all possible temperatures starting from absolute zero, it has always amazed me that in our little world of 100 degrees rail to rail how many things go wrong and KAPUT. Ain't cold a bitch!

[gerty]

I know it's not exactly the same, but fluorescents are like that, they don't like to light up when cold.

[MrAl]

Hi,

Yeah we dont always think about temperature until something goes wrong which is caused by some change in temperature.

Another problem that comes up related to temperature is the shingles on a house. Strange as this sounds at first, if you use very dark color shingles the attic gets so hot in the summer you can cook an egg. Use white color shingles though, and all is well. That's because of the reflectance of the different colors. The sun's energy that hits the earth is quite astonishing, around 700 watts per square meter! If you could absorb all of that, that's like 1/2 of a 1500 watt space heater. So for a roof as small as 20 square meters total area that's like 10 space heaters (something like 14000 watts) heating the attic as long as the sun is out. Yes, it varies as the sun changes angle, but the overall effect is so big that it heats the attic up by many degrees.

While taking a look at this issue i found that the impact is much more than just the attic of a single house. It's so important that the whole area (blocks wide) gets affected such that if every house had a dark roof it could actually raise the temperature of the surrounding air in the whole neighborhood which of course contributes to global warming. Knowing this, the government gives a tax rebate if the home owner uses an approved shingle color, such as what some call "Super White". The reflectance of the shingle has to be 65 percent or better to qualify for the Energy Star rating that allows the tax break.

So temperature is an extremely important issue in this day and age and sometimes it even affects other things we wouldnt even think of.

Temperature (heat) is the reason why our CPU's have a top end speed these days, because there ends up being too much heat to get rid of fast enough to cool a CPU with a speed part a certain limit.

Ever have your car door freeze up in the winter? That's a pain too.

[frhrwa]

funny, reminds me of a Stromberg Carlson Crossreed EPABX in Lexington KY.. I got a call to go out and work on it, the had no incoming ringing, and the folks that came to work on it couldn't fix it.. so.. I think it was the First National Bank of KY.. I went downstairs, turned on the lights and began testing. everything worked fine, all calls came in.. couldn't find a problem to fix.. turned out the lights and left.. all calls stopped.. came back the next day, turned on the lights, and it all worked fine again.. finally, found out the crossreeds that had been used in the matrix were light sensitive, no light, no closure.. first time SC had experienced that problem, they had gotten ahold of a batch of bad crossreeds.. we called it the "afraid of the Dark" switch.. anyway, they replaced the matrix with a new set that had crossreed switches in them that worked.. weird problem..

[Lenp]

We encountered the same craziness years ago with the tremelo circuit in guitar amps. Some used a 'light tight' enclosure for a PE cell and a lamp.
In the cabinet, it worked, out of the cabinet it didn't because of the shop light. Some were affected, others not, but until you realized it, it was a vicious circle!

I once built the the ubiquitous flashing neon relaxation oscillator. Yup, the neon was a bit odd. Case cover on, it would not work, cover off it worked. A small change in a resistor moved the voltage into the range for the neon but until then, it was round and around!

Len