Tell me more ×
Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It's 100% free, no registration required.
up vote 6 down vote favorite
1

I want to make sure my product will work over a large temperature range of -40C to +75C. I can verify on the low end down to about -18C using a household freezer (which is probably good enough) but I'm not sure how to test it on the high end. Any tips?

share|improve this question

6 Answers

up vote 4 down vote accepted

For the high end, you could use a hacked sous vide cooker with a PID controller.

http://hackaday.com/2010/11/06/hacking-together-a-sous-vide-cooker/

share|improve this answer
Ugh. My college blocks "hackaday.com" as "Hacking/Cracking/Computer Crime"... :( – Thomas O Jan 17 '11 at 10:51
up vote 4 down vote

Can you use an oven? Mine can be set to a low around 75 degrees C. I've done cheap temperature cycling tests before by quickly swapping a device between my oven and my refrigerator freezer. I'd just use a TC to measure the actual temperature as the oven readout may not be very accurate.

share|improve this answer
I heard that people had success using convection ovens and PCBs for temperature testing. – AndrejaKo Jan 17 '11 at 16:11
up vote 4 down vote

I've resorted to cardboard boxes with air holes cut into them - allow the product to slowly warm the air inside to the desired temperature and control ventilation to keep it somewhat steady. If more heat is needed, put a power resistor inside the box and use a regulated DC supply to control how much heat it adds to the environment.

share|improve this answer
2  
...And you've never generated any flames? – Kevin Vermeer Jan 17 '11 at 23:28
Not so far :) Mind you, I usually work on stuff in chassis, and push the temps up to 60C. – Madmanguruman Jan 18 '11 at 21:55
1  
@Kevin - Paper only catches fire above 230°C, remember the novel "451 Fahrenheit". Cardboard may be around that value. – stevenvh Aug 22 '11 at 8:29
@stevenvh Any self-respecting switcher usually turns itself off when something goes outside of its SOA (typically 110-130°C) so the risk of cardboard fire is low. – Madmanguruman Aug 22 '11 at 15:29
up vote 2 down vote

Heat gun / paint stripper with adjustable temperature control pointed into an enclosure around your PCB works for the high range, and Circuit Freeze will work on the low end (goes down to -62F).

share|improve this answer
up vote 1 down vote

When I was temperature testing an industrial design I used an old refrigerator; cut a hole in the door and used a heater to drive the temp up to 40C. It didn't smell particularly good but I imagine an insulated metal "box in a box" type design would work very well for your 75C test. Take a look around to see how people make casting furnaces and do something similar.

share|improve this answer
up vote 1 down vote

I once made a small oven to dry my photosensitive lacquer PCBs. It was basically a matrix of 1W resistors directly 230V AC powered. I mounted the resistors 1cm above a PCB so that the air could flow freely around them and the heat was distributed well without hot spots. This heater was temperature controlled by a (unfortunately long obsolete) TDA1024 + NTC temperature sensor.

TDA1024 application

The TDA1024 can be replaced by a transformerless power supply to feed a comparator. My thermostat was set at a fixed 50°C, but with a potmeter you can vary the temperature.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.