No resistor or regulator 5V box mod

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Ralph T

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This mod is an extremely simple and cheap way to make a 5 volt mod that uses 2 3.7 volt batteries. Instead of using a resistor or a voltage regulator, this mod uses diodes to drop the required voltage. If someone else already thought of this, I apologize in advance.

Diodes drop a fixed amount of voltage when forward biased (current flows). The amount depends upon the type of diode, ranging from .5 to .9 volts generally. I bought some diodes rated for 3 amps from Radio Shack and determined that they drop .82 volts each. Three of these in series drop 2.46 volts. So, if used in a two battery setup, whereby the batteries are 3.7 volts (a total of 7.4 volts), we can expect about 4.94 volts at the atomizer.

Here you can see the general layout. Someone with better fingers and eyes than mine could squeeze this into a 3xAA battery box. I needed the 4xAA. :( You cant see it well here, but the black wire, coming from the negative side of the battery is soldered to the diode in the lower left corner of the box. Also, note that diodes have polarity. The white band on the diode must be connected to the negative side of the battery. Otherwise the diodes will be reverse biased and no current will flow (it wont be a workin').
IMG_0270-1.jpg


And, here is the cheesy schematic I drew up.
IMG_0275-1.jpg


Note that the 27x-xxx part numbers are radio shack part numbers. The diodes come two to a bag, so you will need two bags.

The rest of the construction is standard fare for a box mod. I used hot glue to affix the atty connector, in this case a 510 which I got along with the batteries from madvapes.

Edit: Forgot to mention that if you have a 6V mod (two 3V batteries) then you could use just one of these diodes to reduce the voltage to 5.2 volts. :sneaky:
 
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mart.hart

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It is nice to mess about with ideas like this but I realy think most would actually find it easier to solder wires to a regulator than solder a series of diodes.

Regulators can be resonably cheap and the result will, of course, be a stable voltage.

Do you know where you can get a 5v/3a regulator in the UK
I have Googled it to death.

Mart
ps madvapes wont ship :mad:
 

Marctwo

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Well that maybe the best solution if you want the KA378RO5TU. It seems anyone selling retail quantities of these in Europe is still waiting for stock.

You can find other regulators at places like RS, Mouser, Farnell...

Alternatively, you can get free samples of things like PTR08060W from the manufacturers. ;)
 

kemuri

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Ralph T, thanks for the pix and descriptions, made me think.

3 questions for you or anyone who'd like to chime in:

If I were to add a diode to my 5v Nicobox, would it work if I splice it in between the #3 GND pin of a 5v LDO and the neg of the atty? Right now I have the box wired directly from the LDO's GND pin to the atty's body. The #4 control pin on the LDO I don't use since I didn't want any LED's. I will need to use a diode rated differently from yours since my goal is around 4.5V.

Any noticeable heat produced at the diode?

Would it make better sense if my goal is around 4.5V to simply use a resistor rather than a diode, and if so, do I splice in the resistor between the LDO GND and the atty?

The reason for thinking 4.5V now rather than 5V is due to the fragility of the 801 atty. Wonderful vape @5v and 6V but drastically shortened life, and merely just ok and a bit boring @4.2 to 3.7V.
 

Ralph T

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Any noticeable heat produced at the diode?

Very little heat. Nothing at all to worry about. I put one (diode) on my test set and ran the equivalent current (2.3 amps) thru it for 30 minutes straight and it got warm, but not hot to the touch.

As for your other questions... Don't know. I haven't tried a regulator yet. That's next. After that I am going to aim for something that is continuously adjustable from 3 to 6V using (2) 3.7 batteries. It would be nice if the mod had a dial on it so you could set the voltage you want for the juice and atty that is attached. Maybe someone has done this already???
 

kemuri

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Very little heat. Nothing at all to worry about. I put one (diode) on my test set and ran the equivalent current (2.3 amps) thru it for 30 minutes straight and it got warm, but not hot to the touch.

As for your other questions... Don't know. I haven't tried a regulator yet. That's next. After that I am going to aim for something that is continuously adjustable from 3 to 6V using (2) 3.7 batteries. It would be nice if the mod had a dial on it so you could set the voltage you want for the juice and atty that is attached. Maybe someone has done this already???

Thanks, good to know re lack of worrisome heat.

The variable voltage has been done by someone though I have no personal experience vaping it, much less even attempting to fabricate it, though users have high praise for it. I have no idea if he wants to make it public here so I'll PM you, though he has some really nice instructions up elsewhere.
 

Ez Duzit

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Nice one Ralph. Although I prefer a regulator, I enjoy seeing different methods for getting to 5v.

kemuri - you want the resistor, (or diode), between Vout and the atty (in series). And using an 801 atty, (which is about 3.2 ohms), the resistor should be rated about 1 watt, and .33 ohms. That would give you a about a .47 volt drop.
Also, I may be misunderstanding what you said about not using the control pin on the regulator, because you don't want an LED. To my knowledge, the control pin has nothing to do with an LED, (but I could be wrong). Basically the control acts like a mosfet, and allows you to use a tiny 50ma micro switch, instead of some bulky 2 amp rated switch. Being able to use a tiny tact switch, (or any micro switch), is a HUGE plus when building a 5v mod.:)
 
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Ez Duzit

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When using diodes to lower voltage (thus skipping a regulator) is there a way to protect the switch like the control pin does? Does my question even make sense?

I better go to bed....

It's not really protecting the switch, it's just that, that part of the circuit operates at low current. You can do the same thing without a regulator, by using a separate mosfet. But if the goal is a 5v mod using a micro switch, it makes more sense to just use the regulator w/control pin for a constant 5v, vs using diodes to lower the output, and then a mosfet circuit for the switch. I mean, it will work, but it just over complicates it, and it won't be a steady 5v like the regulator will.

Edit- Check out some of the threads in the the MadVapes section of the forum.
 
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kemuri

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kemuri - you want the resistor, (or diode), between Vout and the atty (in series). And using an 801 atty, (which is about 3.2 ohms), the resistor should be rated about 1 watt, and .33 ohms. That would give you a about a .47 volt drop.

Thanks!
Now to look through rshack drawers or find online and pay $6 shipping for a $1 item. :D
 

Ez Duzit

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Thanks!
Now to look through rshack drawers or find online and pay $6 shipping for a $1 item. :D

You can also solder three 1 ohm resistors in parallel which = 1/3 ohm (1/4 watt would be fine since there is 3 of them)

Just find a local electronics parts shop. There's still some around. (rat shack doesn't count)
 

drewk302

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what exact diode did u use? I tried the 1n4001 and 1n4004 and both fried. I tried running through the neg side and positive side. I have a bag of the diodes due to the fact I use the for other builds, non e-cig related. I would imagine those diodes would get very hot?????

I do know that my diodes are 1 amp and I am sure thats why it fried. I am trying to go to 6v from 2x 3.7v 18650 battys
 
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