DIY Thermal Protection

[mkruger]

I'm curious to know if anyone is incorporating thermal protection in your DIY projects? Like small fans that are triggered with thermometors and things like that...

Are there any super quiet fans that you know of?

What tempratures are a safe operating range? I was thinking no more than 100deg. Is this to high? I know I keep my room at about 70deg but i'm sure the equiptment in the racks are getting pretty hot. Plus little components like capacitors are rated for about 120deg.

I'm buildinga mic pre and i was thinking about using a fan with several thermometers.

Let me know your thoughts.

-mike

 

[PRR]

> What tempratures are a safe operating range? I was thinking no more than 100deg. Is this to high?

They let anybody from anywhere in here. Degrees C or degrees F???

> I know I keep my room at about 70deg

Ah, then either you mean F or you are from Venus.

Most electronic docs are in C, just to confuse us Americans.

If spit on your finger sizzles when you touch something, then it is too hot. (In some cases, power resistors are quite happy at boiling-water temps, but I don't like them around more sensitive devices. Vacuum tube glass often idles around boiled-water temp; heater glow is normal, plate glow is bad.)

If you can hold your finger on it forever, it is not too hot.

Cooler is better. But if the box is big and has plenty of air, you normally should not need any "emergency fans". Things either run OK, or something gets sick and burns-up no matter how hard you blow on it.

For power transistors in Class-B audio service, 50 degrees C rise is a time-honored guide. Transistors can cook far hotter. But in Class-B speech/music duty, they heat up and cool down on every thump or syllable, and the constant cycling cracks the seals. Yes, even if the gig is in Antarctica at -50 deg C: cycling from -50 to 0 and back many times a minute is thermal stress, even though the peak temp is cold. Limiting the cycling to 50 degrees C seems to eliminate the problem.

 

[Kev]

[quote author="PRR"]Ah, then either you mean F or you are from Venus. [/quote]


:green: ... lol ... :green: