Recent content by PFF

We have a small power supply (45 watts, 3.75A at 12VDC) want to know how long it will last. Any idea what would be the quickest way to determine this...not withstanding the manufactures word on it. Could load it down and run the heck out of it. Heat it up etc. Ideas? Thanks

Have been using a large variac for about two weeks now. Doesn't work real well but it does allow fine tuning. The problem I'm running into is that I can't get the unit to fail. It shut down once from over heating. After it cooled down a bit it started right up again. It's becoming difficult to...

IRStuff, this supply is for an oven. In the test fixture(an oven) I placed the power supply with a thermocouple attached and a second thermocouple inside to measure the surrounding temperature. The PS does get quite a bit hotter than the surrounding area. So far it's run okay. Haven't been able...

Interesting. objective is endurance. Have had several units fail last year. Wish I had one to look at but I don't. These power supplies run the control circuitry in a hot environment. The area where the PS units are mounted is a bit hot...around 160 F. Just want to test to make sure these PS...

Hey Guys, Got a question about a switching supply I'm testing. The environment it will be used in is typically at 158 degrees F. So I'm testing it in an oven with a load on it to pull max power non stop. How long do I need to test it to determine if these will work for our needs? I could run it...

Thanks Guys. Used a variac. Works good. But now I wonder how long should I test it?

Hi, I'm testing a switching supply that's 45watts at 12 vdc. I put it on a series of power resistors to test it. Set the resistors to 3.2 ohms. After running for a while the resistors got real hot. I turned it off and checked the resistance. It had dropped to .4 ohms due to the heat. How can I...

Thanks for all the advise! Much appreciated.

Hey Guys, Been asked to measure torque on a small electric motor. Any suggestions of some sort of fixture I could throw together to do the job? I'd like to be able to measure the torque at different levels of temperature, current and voltage fluctuations. Thought of using sensors etc. but...

Yes it's correct metengr. In order to substitute teach you have to be certified. I am not certified.

Hi Guys, got a bit of a problem. Just about to turn 60 and am finishing a BSEE. A while back finished a AAS in EET. Before that I worked 34 years as a statistician. Have BS and MS in mathematics and statistics. I retired, went back to school in the EE area because I love EE and hoped to work in...

Thanks for all the input guys!

There are several ways to calculate the two category correlation. You could break the density into several categories then do a chi square to measure strength of relationship. Or you could use a K-category correlation. or you could cook up your own measure if you know the distributions of the...

I thought about filing law suits. Some of these places are actively age discriminating. It's really demeaning to constantly get rejection letters. I get a lot that say I'm over qualified. What the heck is that? How can you become "less qualified"? I'd suggest they are getting a good deal then...

RossABQ, I'm in US State of Wisconsin. Employment situation here is poor but I do see many postings for EE.