'Breaking out' a 3.3v power rail when using a shield (out of pins), MEGA

I’ve searched, but maybe my search terms failed me, so I’m asking:
I’m using a MEGA2560 Arduino with the Sainsmart TFT Sheild to run the 2.8" 240x320 TFT display.
Works like a charm.

However, I plan on using the display to track moisture and humidity, so I now want to connect a DHT22 sensor somewhere onto the Arduino.
As it turns out there’s only the ONE 3.3v pin, and it’s directly injected into the shield that the TFT is using.

How have you hiveminders dealt with this “out of pins” situation?
I’m thinking I could totally hack it, by trying to solder on a ‘breakout feed’ to the side of the 3.3v pin, and feed a small series of pins on a protoboard (with another feed for gnd going back to the Arduino as well)

I can’t be the first person to hit this snag – finding the Mega can only do the ONE thing if using the TFT Shield, but I’m feeling the above is quite the kludge.
Is there a better solution?

The soldering isn't hacking in my opinion. A Shield is just an easy way, not the way to go per see.

Or you could make you own shield that breaks out the 3,3V and that is stackable so you can sandwich it in between the Arduino and LCD.

septillion:
The soldering isn’t hacking in my opinion. A Shield is just an easy way, not the way to go per see.

Or you could make you own shield that breaks out the 3,3V and that is stackable so you can sandwich it in between the Arduino and LCD.

Totally correct. The shield has saved me hours of soldering and redesign, so I suppose this is the price to pay for my laziness.

I don’t think the TFT is even using the 3.3v, as the “instruct are say 5v standard without you not” or something along those lines. I THINK they’re saying it ships 5v factory default, and internally regulates it down to 3.3:

"Voltage type: 5v or 3v voltage input voltage,input is selectable. Because TFT can only work under 3.3 V voltage, so when the input voltage VIN is 5V, need through the 3.3 V voltage regulator IC step down to 3.3V , when the input voltage of 3.3 V, you need to use the zero resistance make J2 short , is equivalent to not through the voltage regulator IC for module and power supply directly.
?

I suppose I could get crafty and snip the 3.3v pin off the shield, and use a 90° header pin off the Arduino.
Hopefully I’m reading the above documentation correctly, and the TFT isn’t utilizing the 3.3v at all.
Sure would be a quick way to find out. :wink:

sainsmart_connector.jpg

sure enough, it was a very quick way to find out.
snips 3.3v pin
–reassembles and plugs in
– nothing. Black. Dead.

Ok, I guess it’s using the 3.3v then. ?

Was I wrong in reading the documentation? It looks like they’re saying if you are using the 3.3v, you have to short jumper J2. I have definitely not done that, so I (obviously incorrectly) assumed that it’s getting its power through the 5v.

How about using something like

Made for Uno so it will not work (directly) if your Saintsmart uses more than the Uno pins

sweet! that's a great idea. I've got enough protoboards and bits and bobs floating around here that I can make one. as they say, "Why buy something for $12, when you can make it yourself with $67 of electronics components?" Thanks though, you got the right spark formed over here. Much cleaner.

Basically @septillon's idea ;) I only visuaslised it.