What resistor or regulator should I use?

[Sir_Lawrence]

Which resistor or regulator should I use to bring (2) rcr123a 3v batteries down to give me 5v?

I bought the 7805 from Radio Shack, it gives me about 5.4v. Now I've been told these are good to use ti over 7v, but not with 6v batteries.

I want to use all three 510, 801, and 901 attys which I know need different amps.

I'm so confused! I just need to know what to pick up again from Radio Shack so I can make a mode that doesn't keep blowing out my 801's like the Silver Bullet does at 6v.

Thank you for your help.

 

[cpcp68]

Yup, the 7805 does not work as it is not a low dropout regulator. I do not know what RS has in stock, but mad vapes sells some very nice regulators for your purpose. If you decide to use a resistor, then use ohm's law to decide the value of the resistor based on your atty resistance.

Suppose you atty is 3 ohm and your batteries are nominally 6V in series, then you need to drop 1V to go down to 5V. The resistor value would be 0.6ohm.

Then you need to make sure the resistor can take the power. The current under the previous conditions is 1.7A, so the power dissipated in your resistor is (0.6ohm)x(1.7)^2=1.7W. It would be wise in this case to use a 2W resistor.

Normally your voltage will not be nominal (6V), and changes quite a bit, so the resistor will not give a consistent vaping experience.

 

[FlipnOut]

Someone else beat me to it