Moving from Development board to vero-board... question on Vdd...

Jed

I've got a prototype running on the BOE and I want to move over to vero-board to make things a bit more permanent. As far as I can tell, if I have anything that's powered by Vdd that is not supplied by a HIGH pin, I need to include a separate 5V Voltage Regulator. Could someone please verify that for me? Also, I see 2 capacitors on the development board in series with the power supply (+ and - terminals). I'm not sure if those are only on the battery or also on the DC wall plug, but is that something I should also incorporate into the vero-board? Is there anything else I'll be missing for proper and safe execution? I'm not worried about re-programming once on the board. This is my first real project and the first time going to vero-board (first time soldering a real circuit, first time lots of different things!) I'm excited but also a bit nervous and want to make sure I solder my first board right. Any help will be greatly appreciated. I'll post the project on the boards once I've gotten everything complete.

Post Edited (Jed) : 2/14/2008 3:11:24 PM GMT

sam_sam_sam

Jed

I alway put a separate 5V Voltage Regulator on all of my Projects unless the load is less then 200 milamp for the hole project these Voltage Regulators do not that much and do not want over load· Voltage Regulator just because i want to save 1 to 3 Dollars

Yes· I see 2 capacitors on the development board

One is on the INPUT· PIN of Regulator and one is on the OUTPUT PIN

The one on the Out Pin is the one you must use

Now if you are powering your project from a wall wart you may want to put one on the in put as well because not all wall wart have enough of a capacitor to filter AC ripple out

When i built my power supplys for my projects i use at least a 47000 uf capacitor then i might·not use one at the input of the Regulator

I hope this help you in what you want to do

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

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Sam

Forrest

You can't go wrong duplicating the 5V power circuit on the BOE, which uses an LM2940-5 regulator and capacitors on the input and output sides of the regulator. If you're in a hurry, you can also use an LM7805 regulator (available at Radio Shack) in addition to the capacitors. Check the regulator datasheet for recommended capacitor values. Typically you'll use 10uF to 100uF electrolytic capacitors rated for twice the design voltage.

If you're circuit is drawing more than 200 mA, typically you'll need to mount a heatsink on the voltage regulator to keep it running smoothly.

Jed

Ok, I'm a bit confused looking at the spec sheet on this regulator, which I'm assuming is pretty similar to what's on the BOE:
parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/txtSearch/regulator/List/1/ProductID/242/Default.aspx?SortField=ProductName%2cProductName

Can I just duplicate what the BOE uses and use 1000uf caps? Is there any harm in going higher, like maybe 3300 uf? so I can order everything from parallax?

Post Edited (Jed) : 2/19/2008 6:24:50 PM GMT

Jed

I see from the docs that it really depends on the caps ESR rating, but I can't find those figures anywhere on the product pages for capacitors here. Is that something that's standard across all caps? (meaning that all 1000uf caps will have the same esr? ) If not, how do I find out, or calculate the ESR of the caps that parallax sells so I know what size caps to get?

Also, from looking at the BOE schematic. It looks like only one of the 1000uf caps is connected to the regulator. The other one is apparently connected to the reset button.

Post Edited (Jed) : 2/19/2008 11:35:26 PM GMT

Jed

bump

RDL2004

Is your project going to run off batteries? If not, just use a 7805 type regulator and keep the V in between 7.5 and 12 to 15 volts or so and you don't have to worry about the ESR of the output capacitor.

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- Rick

Jed

No, it will be running off the 7.5V wall wart that parallax sells. However, I will be running 2 servos and I've heard that the capacitors will help. Is that true?