Power supply for SX48 proto board.

PLJack

I need to power a SX48 proto board with 16V DC from an AC adapter.

I think 9VDC is the max for the proto board.
Is there some simple way to power the SX PB with this adapter?

Thanks.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- - - PLJack - - -

---

Perfection in design is not achieved when there is nothing left to add.
It is achieved when there is nothing left to take away.

Nate

Though somewhat wasteful of power, the cheapest and simplest way I can think of would be a simple 9V zener diode and current limiting resistor·to step the voltage down to where you can use it.

Nate

Jon Williams

You'll be fine with 16v DC -- the regulator may get a little warm but it's good for up to 30 volts. Some people get nervous when the regulator gets warm which is why we put that 9v marking on the board.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Jon Williams
Applications Engineer, Parallax

Chris Savage

Another reason for the conservative ratings is that we don't know what type of power supply is being used.· Many are unregulated, and that can mean that their output is significantly higher than it's rated output when not near or at it's current rating.· So if you'll be using 16V, you should check to make sure that it doesn't go too much higher.· Remember, whatever the input voltage is, depending on the current, the regulator will have to dissapate the remaining energy as heat.· So the higher the input voltage, the more heat generated at the same current draw.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Tech Support
csavage@parallax.com

LoopyByteloose

If you are at all reluctant to directly connect the 16 volt DC, you can 'pre-regulate' it with a 7809.

In that way,
1/ You dump the heat via a regulating device that is off the board and may be sacraficed if you have the wrong hook up.
2/ You have a sure 9Volts to avoid confusion if you mix up power supplies or if you are trying to power a differenct set up that is less tolerant.

Other people think this is all silly, but...

Frankly, I have various Basic Stamps that I want to power directly and I have the SX-48/52 proto board. I also have a mix of other things which include some low drop-out regulators on homemade boards that cannot handle as high a voltage. I also have the SX-28 board.

I jump in and out of projects all the time and may switch wall warts if someone gives me a freebie.

So this is my 'failsafe' set up.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

Jon Williams

Another [noparse][[/noparse]small] reason for the 9v marking on those boards is that they have servo headers and Vin can be connected to the positve supply pin on those servo headers. Servos can tolerate 9v, but anything more and... "Hey, what's that funky smell?"

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Jon Williams
Applications Engineer, Parallax

PLJack

whoops, I started this thread and then forgot all about it until I started working on my project.

Thank you All!
Great stuff. I did not know you could drop so much voltage into a proto board.
That would explain the heat sink on the LM2940.

I like Kramer's idea of a 7809.

Thanks for the prompt response.

Sorry for the delay. I have dropped off this forum as of late but that will be changing soon.
See you all then

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- - - PLJack - - -

---

Perfection in design is not achieved when there is nothing left to add.
It is achieved when there is nothing left to take away.