Can I add 3V3 (or 3V) to my Arduino NG this way?

Maybe this is not the smartest question I have asked here, I am sorry about that :sunglasses:

If I put a 3V3 regulator (only input and GND pins) across the regulator that is already on the Arduino NG and leave the output pin 'free', could I add a 3.3V pin this way?

3(.3V) is really something I am missing on my Arduino NG

... and if this is possible, which regulator would you suggest?

I used TS2950 low dropout regulators on my older boards and they work great. Any 3.3v regulator with a dropout of 1.5 volts or less should work with the input connected to the 5v pin.

Thank you mem!

I found this LM117 on eBay, it has a dropout voltage of 1.2V:

I should be fine with this one, right?

Yes, an LM1117 should work fine. Just remember to install the capacitors on input and output, as shown in the data sheet.

Ordered! Thank you!

I'm curious, why didn't you just jumper a wire from the FTDIs 3.3V? or was 50mAs not enough?

uuuhhh... Didn't realize that this was possible...

lol, oh well, if you bought the lm1117 you will be able to pull more amps through it anyway, which will be handy.

coincidence, i just ordered from the same ebay seller 2 weeks ago. I am still waiting on my cmos IO expanders. I put out a order from seeedstudio on the same day and it came in on monday, so I hope this order comes in soon.

I have ordered from them in the past, that was why I came back to them. They were fine when I ordered the first time.

The FTDI 3.3V output is seriously underpowered. It can't, for example, run the WIZ chip on the ethernet shield, which needs about 3 or 4 times the current that the FTDI is rated for.


I will probably exceed the limitation of the FTDI chip, so I think it was a good decision to buy the LM1117.

Now if there was a simple way of make the digital pins spit out a value of 3V, instead of 5V... I bought this to overcome that problem, but it would be nice if I could arrange that in the software or through a jumper:

Did you ever receive an email from that ebay seller that your items were shipped? I ordered Friday and received a message on Saturday morning that my item was shipped.

Now if there was a simple way of make the digital pins spit out a value of 3V, instead of 5V

You would need to run the board on 3.3volts instead of 5 volts if you want 3.3v levels on the pins without external hardware. But at 3.3v the clock needs to be 8Mhz instead of 16Mhz so its not an easy change to make to an existing board. You can purchase 3.3v boards, for example:

Thanks Mem. For now I will stick with my NG and use the sparkfun boards I linked too.

I have a RF board that needs 3V, so that is why I ask. If I ever get it to work, I will buy the board you linked to or make something simple that works completely on 3V

@crashingdutchman: yeah i recieved the email the next day saying that it had been shipped. I still haven't recieved the package though, and tomorrow is going to be 3 weeks since the email.

"the clock needs to be 8Mhz instead of 16Mhz so its not an easy change to make "

Actually it is as easy as burning the lilypad bootloader to your *duino. It will run on the internal oscillator at 8mhz regardless if there is a crystal attached or not.

@darude: hmm. That is a bummer. I assume you have contacted them?

So, I could make the board switchable between 5V and 3V3 and just use the appropriate bootloader for the voltage I have selected?

you would probably have to live with 8mhz for both 3.3v and 5v, unless you want to get real complicated.

FWIW, I've been running the ATmega168 at 3.3V with a 16 MHz resonator on about a dozen units with no ill effects whatsoever. Same reason as crashingdutchman, i.e. to connect a radio module which doesn't tolerate 5V.

So far, all my boards work just fine, at room temperature anyway... One of the units has been running continuously for over two months now.


PS. @crashingdutchman, if you're dutch: groetjes!