Resistors for 6v down to 5v

[Sir_Lawrence]

My (2) 3v rcr123a batts fresh out of the charger read 6.67v. What resistor should I used to get this down to 5v?

The Radio Shack 5v regulator only brings it down to 6.13v. So this didn't cut it. Someone suggested a 100ohm 1/8 watt resister.

Any help would be great!

Thank you

 

[Wagex]

you must have not wired it up correctly or you got a bad regulator... but if you want to use a resistor
The wizard recommends a 2.7 Watt capable or greater 1.2 ohm resistor. The color code for 1.2 ohms is brown red gold.
a 100 ohm resistor would bring you to like 4.5v and 1/8 watt would be like 30 ma and most attys require atleast 1000ma

 

[Sir_Lawrence]

Hi, thanks for responding. I'm hooking up the right way according to the diagram and exactly how people in these rooms have told me. I bought 3 of them and all 3 are giving me the same readings.

 

[FlipnOut]

I'd assume bad regulator too, maybe ya caught it with some static? What's the loaded voltage coming out to be? Maybe the regulator needs a load to level out.

 

[dubnluvn]

you must have not wired it up correctly or you got a bad regulator... but if you want to use a resistor
The wizard recommends a 2.7 Watt capable or greater 1.2 ohm resistor. The color code for 1.2 ohms is brown red gold.
a 100 ohm resistor would bring you to like 4.5v and 1/8 watt would be like 30 ma and most attys require atleast 1000ma

I agree. I have the 7805 5V regulator from Radioshack and I get 4.95V at the atty. The left pin is input middle is ground and right is output. Make sure you wire regulator ground inline betwen the battery and atty.

 

[Sir_Lawrence]

So how do I check it with a load?

 

[Sir_Lawrence]

I was told you didn't need to wire the ground to anything. The negative from my battery is the metal casing. So I also need to wire the middle pin to the casing as well?

 

[FlipnOut]

Yes, the ground should ground the atty connector, and the center pin of the regulator. Checking with a load simply means checking the voltage at the atty connector, with an atty connected and the button pressed.

 

[Sir_Lawrence]

OK... so what I did was just hook another wire from the center pin to the metal casing, where the neg of the battery is touching. I'm now getting a reading of 5.5! I can live with that. Thanks

 

[Sir_Lawrence]

So basically, the regulator needs to be grounded as well to work, correct?

 

[FlipnOut]

Precisely. Remember, electricity always chases ground. So, with no ground to the regulator the electricity had nothing to chase.

 

[Wagex]

lol yea il draw a diagram

 

[FlipnOut]

That diagram would work great for something that is always on.... Maybe a switch would be in order for the rest of us

 

[Ez Duzit]

I don't want to pop anyone's bubble, but a radio shack 7805 will absolutely not put out 5 volts with an atty attached, since they're only 1 amp max output. An e-cig at 5 volts will draw between 1.5 and 2 amps, and sometimes even a little more then 2 amps.
mad vapes has some great regulators which are 3 amps max, and also have a control pin. That means you can use a micro switch without worrying if it will handle the current. But using the control is only an option. You can wire it the same as any 3 pin regulator, by simply not connecting the control pin. But if you look at the last picture in the description of the regulator, (Not the 5th but the 6th picture), he posted the circuit, with the control pin connected.

MadVapes 5 volt 3 amp regulator with control pin


Here's a better diagram of a basic 3 pin regulator circuit for an ecig. The LED is optional.

 

[Scottbee]

I don't want to pop anyone's bubble, but a radio shack 7805 will absolutely not put out 5 volts with an atty attached, since they're only 1 amp max output. An e-cig at 5 volts will draw between 1.5 and 2 amps, and sometimes even a little more then 2 amps.

You're "as right as rain". The 7805 in the TO-220 won't do much about 1A.... and even at that you'd best heatsink it pretty well. The 7805 in the TO-3 package can sometimes be coaxed up to 2A... but once again the heatsinking is a must.

Linear regulators and resistors really aren't the way to go.. especially if you are concerned about efficiency and battery life.

 

[Sir_Lawrence]

With this regulator from mad vapes, can you use a micro switch rated for .5 amps using the control pin? What resister do you tie in?
If you don't use the control pin, will a .5 amp switch work?

 

[Ez Duzit]

With this regulator from Mad Vapes, can you use a micro switch rated for .5 amps using the control pin? What resister do you tie in?
If you don't use the control pin, will a .5 amp switch work?

.5 amp switch using the control pin is fine. Check out the tiny tactile switches he also sells, which are perfect as the switch.

The resistor (I think) was 470 ohms, check the schematic.

With out the control pin, there's still that 1.5 to 2 amps going thru the switch. So I'd say no to the .5 amp rating. Although it might work for a while, it definitely wouldn't be happy about it.

 

[Wagex]

yea his tactile switches athat are rated at 50 ma run my 901 awesome without a regulator or anything of course... nto even a mosfet lol he has the best deals around... most of the times he sends spares too

 

[CaSHMeRe]

easier route would be a resistor ...

.4 - .6ohm / 2watt will get the job done, and drop you to around 4.7 - 5.2v loaded using (2) 3.0v batteries (whether that CR2's or CR123's)

 

[vVegas]

Why using resistors ??? Use a simple diode to bring the voltage 0,7V down or a combination of a diode and a hot-carrier-diode (for 1V)....