The Lung Lolly How to do Automatic 5V /3.7V selection???

[Silverthorn181]

My Lung Lolly!!

This is my 3.6 / 5v Lung Lolly that I am attached to every waking moment. For me it’s just about as perfect as I can imagine except for one very small thing I want to change.

It is set up for KR808 Cartos and a single Protected 14500 bat for regular vaping and with an extension tube and a second 14500 it gives a regulated 5.1V.

To allow either configuration I have built the regulator into a slug that slips into the top of the tube between the batteries and the switch circuit when in the 2 bat configuration and a blank slug for single bat 3.6 vaping.

If you do leave the regulator slug in with a single battery the output from the regulator is only about 2.5V and obviously won’t drive the device. It’s not a big thing to swap the two over except the slug must be a tight fit in the tube to give a good ground for the regulator and after a couple of beers this can challenge my motor skills!! Also it’s just another thing to lose!!

What I would like to do is to change the circuit to have the regulator permanently in place with some way of sensing the voltage available and when it is below say 4v automatically bypass the regulator and send power directly to the switch circuit.

I have looked a varisistors but can’t find anything that I think would work. Polyswitches work on current not voltage so wouldn’t work either. I am looking for a small voltage sensing device that is normally closed (power directly to carto) and opens (power to regulator) when the voltage reaches 4V. The reverse of a PNP power transistor.

Alternatively a regulator that will regulate the 8V back to 5V without causing a brop at 3.6V.

If anyone can help with a circuit or device for this or point me in the right direction I would really appreciate it!!

 

[Connman]

The only trouble I see with this is my other mods. Sure fits the bill with a one mod type scenario though. Very good Idea. I shall look further into using this idea as the matter of fact.

One mod is like just not right though.

 

[four2109]

That's nice, I like the size of the single batt mode. Could you elaborate on the "regulator slug". Thanks

 

[Silverthorn181]

That's nice, I like the size of the single batt mode. Could you elaborate on the "regulator slug". Thanks

Rather than having the regulator soldered and floating around in the head I encased it with potting mix in a small cylinder 7mm long and the diameter of a battery with the in and out terminals connected to the front and back faces and the - and case soldered to the brass band around the outside. This not only gives the negative connection but allows the whole case to work effectively as a heat sink. For single battery I just slip it out and replace it with a blank slug. It works really well and is easy to make if you have a small amount of room.

 

[IR_Efrem]

+5V Fixed-Voltage Regulator 7805 - RadioShack.com

I do believe that you can buy these in a smaller package. They are .5 amp but it is a simple thing to piggy-back them onto one another to achieve desired amperage.

4 in a single circuit would give you 2amps, etc etc

Look around, I know (I could be wrong though, heh) the 7805 comes in SMT and higher amperage as well.. 1.5amp perhaps? Use yur google skilz =)

 

[quasimod]

That looks to be exactly what I need just as it is: I'll take 2 please.

 

[Silverthorn181]

+5V Fixed-Voltage Regulator 7805 - RadioShack.com

I do believe that you can buy these in a smaller package. They are .5 amp but it is a simple thing to piggy-back them onto one another to achieve desired amperage.

4 in a single circuit would give you 2amps, etc etc

Look around, I know (I could be wrong though, heh) the 7805 comes in SMT and higher amperage as well.. 1.5amp perhaps? Use yur google skilz =)

Thanks but it already runs a good 3A 7805 regulator. That is what is in the regulator slug. But that also drops the voltage when I use a single battery. That is why it is mounted in a slug so I can remove it for 3.6V vaping. I want either a regulator that won't drop the voltage when the supply is only 3.6V or a voltage sensitive solid state that can switch the regulator on when it senses 8V at the supply and off when it senses 4V.

 

[VaporX]

look up LED voltmeter projects

they will teach you to make a design that can be set to a volatage or more that one,

then replace the led at the voltage u want with a relay to the atomizer

a bit more to it than that, but it will get you started

 

[Silverthorn181]

look up LED voltmeter projects

they will teach you to make a design that can be set to a voltage or more that one,

then replace the led at the voltage u want with a relay to the atomizer

a bit more to it than that, but it will get you started

Good thinking and a great lead but all of the methods I can find there also cause a voltage drop at 3.6v. Usually about 0.7v and that's no better than just running straight through the regulator. Unless I am missing something???

 

[5cardstud]

What about a small a b switch on one side 5v on the other side 3.7?

 

[Blaze]

It....is.....beautiful!!!!!!!

When you decided to start making these commercially, hit me up with a PM, I'll take one

 

[Israfil]

Reminds me of a black lightsaber, very sexy. I'm having a similar problem trying to figure out how to get the voltage of 3 3.7 volt lithium batteries to drop down to around 5 volts.

 

[VaporX]

Good thinking and a great lead but all of the methods I can find there also cause a voltage drop at 3.6v. Usually about 0.7v and that's no better than just running straight through the regulator. Unless I am missing something???

Thats where the little bit more comes in. there is some math to figure out how to adjust it to give you 3.7(or what ever voltage) to the atty, then when it reaches an unacceptable level it will cut out. the voltage drop is gonna be a tough one to overcome. a good bit of effort

Or

look at flashlight drivers circuits, constant current.
for example:
one driver can accept input of 5-9volts it outputs a set current until the voltage causes it to not be able to, it then and falls out of regulation.

what this would do for you is, when over 5 volts is detected it will provide a set current to the atomizer, BUT if you use 1 battery it will not kick in the regulator and allow it to run directly from the battery

 

[Silverthorn181]

Thats where the little bit more comes in. there is some math to figure out how to adjust it to give you 3.7(or what ever voltage) to the atty, then when it reaches an unacceptable level it will cut out. the voltage drop is gonna be a tough one to overcome. a good bit of effort

Or

look at flashlight drivers circuits, constant current.
for example:
one driver can accept input of 5-9volts it outputs a set current until the voltage causes it to not be able to, it then and falls out of regulation.

what this would do for you is, when over 5 volts is detected it will provide a set current to the atomizer, BUT if you use 1 battery it will not kick in the regulator and allow it to run directly from the battery

Ok I don't yet understand what you are saying but that sounds like you are pointing me in the right direction. Now I'll go off and research but if you could dumb it up a bit for me that would help. If I am understanding correctly so far I would use the circuitry that the flashlight driver uses it would allow up to 5V to go straight to the atty (carto in my case) and when I put the second battery in rather than using a voltage regulator this would limit the current. I assume that by limiting the current (by way of resistance?) that would also reduce the voltage?

I had thought of the simple dip switch in the head solution and will keep that up my sleeve as a last resort!!

Thanks Guys for your help!!

 

[VaporX]

its tough to dumb it down as these are complex devices

but basically if you find a "driver" or get one made for you, it can have certain qualities

-first the output would be set to what you want, volt and amp by the maker(technical part)
if the driver accepts (for example) 5-9volts input (two batteries) that means when any voltage in that range is detected it will provide the set output you defined.

-when the input to the driver is less than the set range (under 5V in this example) it will bypass it(the driver), allowing the single battery to act as it normally would.

-if you apply more than the max voltage it will destroy the driver

hope this helps

 

[Silverthorn181]

VaporX, Thanks that's been a huge help!!

I was wondering if I could impose on you for some further input here. As a result of your pointing me in the right direction I am now able to start making intelligent conversation on the subject!! As you have said the Constant Current Driver Circuits are complex little suckers and the majority I have been looking into have more components in them than I have had hot dinners!! Still reading, reading there.

In researching Driver Circuits obviously I have also been looking at Buck/ Boost Regulators. I'm thinking of them not in their traditional application but in a variation of it. I do not want a constant 5V as would normally be produced from a 5V Buck/ Boost Regulator. I am thinking that when on 3.6V I have a Voltage drop of between .7 & 1V. So what I am toying with is a 5V buck side with an input (not output) boost of 1V to compensate for the Voltage drop across the Buck Regulator. But I fear that efficiency would be my enemy here!! From what I understand I would be feeding an item that is approximately 80% efficient with an item that is 80% efficient resulting in a circuit that would be less than 65% efficient and the losses would be enormous!!

Your thoughts??

 

[VaporX]

I Just noticed you are from down under, good news for you!

Call cutter(dot)com(dot)au they will be able to help with getting the proper parts, and more detailed technical help.

Dont get too hung up on efficiency, if you shooting for 100% good luck it wont happen, ever.

 

[yes8s]

Ok so I think I can offer some advice here being an electronic engineer...

1. What you're are trying to acheive can be done with the 5v reg, a couple of high power transistors and a few resistors (too late now to give exact details). Only problem here is the component packages will be a little large because of the high currents that the attys consume. Size can be compromised at the expense of reduced lifetime of the circuit.

2. Whilst the 78xx series of regulators are good and simple to use they have a dropout V of about 2-2.5V, meaning you will need a supply of at least 7.5V for a steady output. So already efficiency is down because you losing 2.5V * ~2A = 5watts.

I would suggest using a buck/boost controller for this application. You can set this to whatever voltage output you want and it will work with a wide range of input voltage. It will also give you a steady output almost untill the battery(ies) are dead. Efficiency here would be much better than the 7805. And you can get HV vaping on 1/2/3 batteries - only vape time would be affected and not voltage or current (assuming a suitable circuit is found)

Or you could just use a switch as has been suggested. Easiest way by far.

High powered LED torches use this to give a good output with a small footprint. Have a look at Dealextreme.com as I beleive they may have something suitable for a good price in a small package.

Let me know if u need more info or discussion.

 

[Silverthorn181]

Need more info and discussion!!!

After considerable time researching and knocking up a couple of experiments I have discovered some interesting things. The most important outcome of my testing is the discovery that my preferred Voltage is actually between 4.2 and 4.7V.

This revelation has lead me towards the buck/boost controller fixed at around 4.5V for both battery configurations. That should also give a consistent Vape with both setups while only slightly shortening the live of my single Bat setup and extending my two Bat vaping time.

Looking for an appropriate setup for LED torches and Nada!!! So now I'm looking for a driver board that I can mod to give those results. I've had a good look at the driver boards on DXT and the form is Perfect and one or two come close to my requirements but nothing is right.

This little sucker comes close but the size is a little big and it will only provide 0.5A Adjustable Step up/Step Down DC Voltage converter. Anyvolt Micro. Am I heading in the right direction? To be perfect it would also have a control pin for my switch!!

Alternatively this http://www.blip.com.au/item.aspx?itemid=21 would give me 5V from my single 3.6V bat but then I would need some way of not blowing it when 8V goes through it...... And so I come back to a switch...

As you can see I have started chasing my tail running from this possibility to that and back again.. I'm a little more educated now and just starting to get dangerous so I need a slap up the side of the head and a reality check from someone with some know how!!