View Full Version : parallax proto board running at 11.1 volts

07-07-2009, 10:19 AM
i recently received a display that run on 9 to 24 volts. the battery i have outputs 11.1, can the proto board regulators handle this or do i need a seperate regulator from the battery before the proto board. any info is helpful

Mike Green
07-07-2009, 10:32 AM
The Protoboard's regulators can certainly handle this voltage. It's the heat dissipated that's the issue. At 11.1V, the 5V regulator has to dissipate 6V x <total current> Watts of heat without a real heatsink. The 3.3V regulator runs off the 5V supply, so it doesn't have much heat to worry about. If all the 5V and 3.3V circuitry on the Protoboard draws 1 Amp, that's 6 Watts of heat that has to be dissipated. That's a bunch in a small area with no heatsink. You can glue a small aluminum heatsink to the top of the regulator package. If you use metal-filled epoxy and attach it to the regulator tab as well being careful not to short out anything, you'll do better.

Loopy Byteloose
07-07-2009, 03:22 PM
The 5volt regulator will handle it, but run hot. That''s why an added heat sink is recommended. In some cases, regulators have been know to just melt the solder and slide off the board without internally failing. So it is all about heat.

I happen to have a 12v TV display. Running everything off of one source would be an advantage. So I also might try to epoxy a heat sink to the 5volt regulator.

One could insert a 9v or 7.5v regulator in line to dump the heat if you don't want to mess with the board and adding heat sinks

Ain't gadetry a wonderful thing?

aka G. Herzog [ 黃鶴 ] in Taiwan

Post Edited (Loopy Byteloose) : 7/7/2009 10:49:31 AM GMT

07-07-2009, 07:14 PM
Are there any disadvantages to having multiple power regulators off of one power source, where each regulator's input comes from the former's output? ie: 12 volt source -> 9 volt -> 5 volt -> 3.3 volt regulators.


07-07-2009, 07:24 PM
There's nothing wrong with that, apart from it being expensive. I'd just use a switcher.


Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

07-07-2009, 07:29 PM
I use a protoboard with a 12V battery and it works well. Attached I have 2 LCD3 serial display and a GPS.
The heat in my case is below warning zone, but when I tested the back light on the LCD a strange smell suggested to avoid back light..

07-07-2009, 07:50 PM
thank you much for the info, since i already have the epoxy and have the heat sink ill go that route, i dont know my current draw, but i think i need to figure it out for future reference. Thank you much for the help.