Search found 3705 matches

by JR.
Sun Jul 13, 2014 6:07 pm
Forum: Pro Audio Design
Topic: Smart crock pot -looking for fan cooled heat sink.
Replies: 33
Views: 91009

Re: looking for fan cooled heat sink.

In light of the fact that this thread has gotten hundreds of views, I should mention that my thermal igloo idea is not recommended for use with a gas burner. The gas stove needs air turnover for the flame. I guess one could punch a hole in top for exhaust, and slots for fresh air inlet on the bottom...
by JR.
Sat Jul 12, 2014 12:00 pm
Forum: Pro Audio Design
Topic: Smart crock pot -looking for fan cooled heat sink.
Replies: 33
Views: 91009

Re: looking for fan cooled heat sink.

I like the power resistor idea. I saw this recently in Electronic Products and thought of you: http://www.ovenind.com/pdf/DS-5R7-573.pdf Yup that is a viable way to control them and I was headed in that direction. You can drive a Peltier device with PWM or duty cycled DC as long as the full scale D...
by JR.
Sat Jul 12, 2014 10:49 am
Forum: Pro Audio Design
Topic: Smart crock pot -looking for fan cooled heat sink.
Replies: 33
Views: 91009

Re: looking for fan cooled heat sink.

I am still waiting for my power resistors but I have started using my heat igloos for my normal stove top cooking and I am noticing more cooking from lower heat settings and less heat into the room.... Sweet. It seems to me that we need a new kind of cooking pot that is built like one of those japan...
by JR.
Thu Jul 10, 2014 10:51 am
Forum: Pro Audio Design
Topic: Smart crock pot -looking for fan cooled heat sink.
Replies: 33
Views: 91009

Re: looking for fan cooled heat sink.

The Peltier device and chip cooler was too clever to be effective. At the end of the day by closing the air inside a box I kind of defeat the heat transfer to ambient and the Peltier device is making more self-heat than pulling anything useful from ambient. A second critical limitation is that the P...
by JR.
Wed Jul 09, 2014 8:37 pm
Forum: The Peabody Lounge
Topic: Entropy
Replies: 1312
Views: 1075324

Re: Entropy

Air Conditioner spares. Last night the 2007-era AC compressor failed. It took us about 15-20 minutes to notice the house getting hot. I immediately discovered both the compressor and condesner fan not running. Power was making it to the switched side of the contactor. I could hear the compressor at...
by JR.
Tue Jul 08, 2014 7:50 pm
Forum: Pro Audio Design
Topic: What happens when two "virtual ground" buses short?
Replies: 3
Views: 9774

Re: What happens when two "virtual ground" buses short?

I would expect the two opamps to "share" proportionately based on their open loop response. If the two opamps are very close to identical It might only express as the routing error (two buses play when only one is assigned). If the two opamps are not identical (and they wont be) their outp...
by JR.
Mon Jul 07, 2014 1:19 pm
Forum: The Peabody Lounge
Topic: Entropy
Replies: 1312
Views: 1075324

Re: Entropy-solar lamp repair update

Well charging the battery through the base-emitter junction works fine, I didn't like it turning on so soon before dark,effectively as soon as the solar cell voltage drops down equal to the fully charged battery voltage. I added two more resistors to the circuit turning on the NPN to turn off the L...
by JR.
Mon Jul 07, 2014 9:43 am
Forum: Pro Audio Design
Topic: Smart crock pot -looking for fan cooled heat sink.
Replies: 33
Views: 91009

Re: looking for fan cooled heat sink.

I figured out how to sense temperature of my hot-plate. I have some old medium power transistors with large thin heat-sink tabs. I will use two of these under the fan attachment legs/screws, then I'll wire the two base-emitter junctions in series, and read the voltage with an A/D input. Tempco is ar...
by JR.
Sat Jul 05, 2014 2:48 pm
Forum: Pro Audio Design
Topic: Smart crock pot -looking for fan cooled heat sink.
Replies: 33
Views: 91009

Re: looking for fan cooled heat sink.

OK, I have figured out why perhaps a Peltier device was not the optimal approach, but I am this far down the road, lets see how close I can get. At least we can all learn from my mistakes. :oops: I just did another experiment, I figured if I could get the cold side hotter, the hot side would get hot...
by JR.
Fri Jul 04, 2014 10:05 am
Forum: Pro Audio Design
Topic: Smart crock pot -looking for fan cooled heat sink.
Replies: 33
Views: 91009

Re: looking for fan cooled heat sink.

OK, after an overnight cooking test I am now smarter about Peltier effect... :roll: My rig gets too hot to touch but does not put out enough heat to cook. It appears that I was over optimistic about how much heat this would pull from the room air, and miscalculated how much current the 12V supply wo...