BS2sx voltage regulator question....

deno

Most of my homebrew stamp projects are based on a 12 volt supply, whether it is for the house, car, boat, or the golf course...(Robo Caddy).· Now, I do know that the BS2sx voltage regulator doesn't really like 12 volts, as it runs alittle hot.· I also know that I can supply an external voltage regulator (7805) with a heat sink to solve this heating problem on the stamp itself.· But,...the question for the day, is...has anyone come up with any good ideas for a small heat sink glued to the top of the small regulator on the stamp to disapate some of the heat?·

Since this is about the BS2sx, I am not sure if this post belongs here or over in the SX microcontroller section.

Thanks· DenO

Mike Green

Go to a hobby store and buy a piece of aluminum rod slightly narrower than the regulator on the Stamp module. Buy some metal-filled epoxy glue (usually powdered steel).

Cut the aluminum rod with a fine hacksaw to maybe 1/4" in length and carefully file the cut end with a fine file so it's flat and smooth.

Mix up a small quantity of the epoxy and use a toothpick to put a thin layer on the top of the regulator, then firmly set the piece of rod in the epoxy and set the module aside until the epoxy hardens.

This will provide a little bit of heatsinking. It's not much, but it's easy to do. You'll get the most benefit from your efforts by reducing the level of Vin or completely using an external 5V regulator and running the Stamp with Vdd supplied by that (with Vin unconnected). If you plan to continue using 12V supplies, get used to using switching regulators. There are a variety of small, ready-made 5V switching regulators that can be substituted for the LM7805 directly. They're not that expensive and will avoid the heating problem.

Franklin

One way to help with the efficiency is to get a switching regulator. They are more efficient and don't waste the extra power but switch to regulate the level.

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- Stephen

deno

Thank you Mike and Franklin for your replys.· I have been tempted to do exactly what you suggested Mike, but was wondering if anyone has tried it.·

Actually, this project was built around a regular BS2, but when I started writing the code for the job, I went over the EEPROM limit of the BS2.· I had to·substitute a BS2sx and write the code in different program slots.· The PCB was already ordered by that time using Vin on the stamp instead of Vdd. I really hate to go in and hack a brand new PCB after I spent some much time doing the art work.· I did know that the BS2sx doesn't like 12 to 14 volts, which is what a typical 12volt system sees.· I will try your suggestion, Mike, and install a very small cooling fan to blow on the aluminum.

DenO

deno

Just thought some of you might like to know that I seemed to solve the heating problem of the BS2sx voltage regulator.· Thank you Mike Green for the idea.· Please see the attached photo.· I used a small dab of JB Weld to hold the aluminum heat sink to the regulator face.· The heat sink itself I cut from a larger heat sink designed for a T220 case.



Deno

sam_sam_sam

I use switching regulators for more of the project that I am doing

One word of caution·about BS2sx chip they do use more current than a BS2 chip and your regulator runs·a lot hotter than the other

BS2···· =··· less than 10 milliamp
BS2sx· =··· about 70 milliamp

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··Thanks for any··that you may have and all of your time finding them

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Sam

xanatos

For what it's worth, I ALWAYS use an external 5v regulator for my BS2sx-based projects that are powered by AC. The only thing the on-board regulator has to power is the BS2sx itself.

Best,

Dave

deno

I do know that the BS2sx uses alot more current.· The orginal project was designed around a regular BS2.· Then when I deceided to expand the project with joy stick control, I ran out of EEPROM room.· The circuit board was allready designed and delivered and populated with components, so I was unable to use a 5 volt reg without hacking the board up.· So this is sort of a quick fix...that seems to work.· Sorry for the large picture, but I am still have trouble resizing photos to a smaller file size and still reconize the photo.

DenO