EverCool Variable Voltage Mod

[raceengine]

out of curiosity I ordered a sample from TI... 3 days later (today) I received a FedEx Parcel shipped all the way from the states to Malaysia. Very impressive customer service I must say... Thanks everyone for all the informations... will try to find the time to build my very own everc00l...

 

[breaktru]

That was very fast service. Maybe I should move to Malaysia

Keep us updated w/ your progress on the mod

 

[rchriste]

Again, I am a newbie and I do not understand what I wrote that was unfair but I am truly sorry. Please explain. This is all new to me.

Unfair probably isn't the word I would use but is guess in a sense, it's unfair to the original poster who started this thread. It's his thread and it's about his idea.

I can sure appreciate your thirst for knowledge and I don't think that should ever be squelched. Everyone has been a newbie and everyone has probably made this mistake to some degree. You seem defensive about the comments about starting a new thread. Those comments really are good advice and I do hope you won't be put off by sound advice.

You bring up a few good points and changes you would like to make to the Evercool mod. I think most anyone would support that.

What people are commenting about is that while the changes may very well be great ideas, those changes would make the mod something other than the evercool mod. In that sense, it would probably be best to start a new thread about it. Changing the evercool mod *IN* the evercool mod thread is considered hijacking the thread and that's frowned upon. Also, people wishing to build the Evercool Mod need support and this is where they come to get it. Most everyone strays now and then. No biggie. When the straying becomes consistent then it's probably time to start a new thread. When you look at the changes you've proposed and put them all together, we're looking at something that doesn't even resemble the Evercool Mod anymore. There's nothing wrong with that, it just deserves it's own thread. And maybe a name.

Big blue presented this mod for the benefit of all. If he had asked for ideas on how to improve it then anything would go and this would be a free-for-all. Since he didn't ask for improvements, then the thread is to support people that want to make his evercool mod.

I agree that the.vapyre's ideas to modify this BigBlue Evercool mod deserve it's own seperate thread and I would be interested in following his progress in that separate thread. It's so easy to start a thread on this forum. I hope he will also support those that wish to keep this thread intact for the people who wish to build the Evercool Mod presented by BigBlue without having to sift through mountains of wild tangents (be they good or bad ideas).

If any of that offends anyone, then simply disregard anything and everything I say. <grin>

 

[the.vapyre]

Now that you have explained it so well, I understand and agree. I didn't think of it that way. No offense taken. Sorry to Big Blue and thank you for this thread. I have learned a lot from it and have really enjoyed learning all this complex stuff. I can tell it is a great mod. I definitley will start a new thread and will probably still build my own without the USB.

Unfair probably isn't the word I would use but is guess in a sense, it's unfair to the original poster who started this thread. It's his thread and it's about his idea.

I can sure appreciate your thirst for knowledge and I don't think that should ever be squelched. Everyone has been a newbie and everyone has probably made this mistake to some degree. You seem defensive about the comments about starting a new thread. Those comments really are good advice and I do hope you won't be put off by sound advice.

You bring up a few good points and changes you would like to make to the Evercool mod. I think most anyone would support that.

What people are commenting about is that while the changes may very well be great ideas, those changes would make the mod something other than the evercool mod. In that sense, it would probably be best to start a new thread about it. Changing the evercool mod *IN* the evercool mod thread is considered hijacking the thread and that's frowned upon. Also, people wishing to build the Evercool Mod need support and this is where they come to get it. Most everyone strays now and then. No biggie. When the straying becomes consistent then it's probably time to start a new thread. When you look at the changes you've proposed and put them all together, we're looking at something that doesn't even resemble the Evercool Mod anymore. There's nothing wrong with that, it just deserves it's own thread. And maybe a name.

Big blue presented this mod for the benefit of all. If he had asked for ideas on how to improve it then anything would go and this would be a free-for-all. Since he didn't ask for improvements, then the thread is to support people that want to make his evercool mod.

I agree that the.vapyre's ideas to modify this BigBlue Evercool mod deserve it's own seperate thread and I would be interested in following his progress in that separate thread. It's so easy to start a thread on this forum. I hope he will also support those that wish to keep this thread intact for the people who wish to build the Evercool Mod presented by BigBlue without having to sift through mountains of wild tangents (be they good or bad ideas).

If any of that offends anyone, then simply disregard anything and everything I say. <grin>

 

[rchriste]

Now that you have explained it so well, I understand and agree. I didn't think of it that way. No offense taken. Sorry to Big Blue and thank you for this thread. I have learned a lot from it and have really enjoyed learning all this complex stuff. I can tell it is a great mod. I definitley will start a new thread and will probably still build my own without the USB.

Hopefully I'll find your new thread. It could really prove interesting. Seriously! An on-board charger sounds more convenient than pulling bats daily. That might actually be a great idea.

What you said about building one without the USB.... Since you're new and might have questions about how to 'make it work', the evercool mod is a great place to start. It's not only a great mod, cost effective and durable, but it's also got lots of info on problems you might face. So you build the evercool first and then move on to improving things. I never really thought of it that way before but I think you've hit on a good idea for anyone new to this kind of modding. Start with the known and work your way to the unknown as it were.

However you decide to proceed I hope you get to where you want to be with little trouble.

If you do decide to build an evercool, I personally would like to hear how it's going for you in here as well.

 

[sierra22]

out of curiosity I ordered a sample from TI... 3 days later (today) I received a FedEx Parcel shipped all the way from the states to Malaysia. Very impressive customer service I must say... Thanks everyone for all the informations... will try to find the time to build my very own everc00l...

wow, i live in the states and it takes 7 days fedex to get to me!

 

[CraigHB]

TI is very generous about shipping samples. They give you the option of overnight and 2nd day. TI is the only company I've used that will do that. I order samples from a lot of different makers. Normally, they dont' give you an option and just send it FedEx/UPS ground or USPS priority/first class.

Free samples are one of the great things about doing stuff with electronics. You'd be surprised how much you stuff can get for free with a little digging, sometimes expensive stuff. For example, the output caps I'm using on my mod are $5 each and the circuit uses two of them. Kemet sent me 20 when I asked for samples, 100 bucks worth of caps for free, as in gratis, not even shipping charges.

 

[Old_Trekee]

Received a status email from TI. My samples shipped out of Texas on Monday and are expected to arrive here in Ohio on Wednesday. Excellent service. I thought they were coming FedEx Ground, but must be 2nd Day. I won't even have my other parts from Digi-Key and Madvapes by then.

 

[the.vapyre]

Thanks bigblue30 for sharing this with us! That was so generous of you to enlighten us all with your superior mod concept! You have generated such great feed-back, explorations, and developments too! What a great thread this has become. I personally think you have started a minor e-cig revolution. I have learned a lot from it. I am anxious to see what you come out with next.

 

[bigblue30]

Thanks bigblue30 for sharing this with us! That was so generous of you to enlighten us all with your superior mod concept! You have generated such great feed-back, explorations, and developments too! What a great thread this has become. I personally think you have started a minor e-cig revolution. I have learned a lot from it. I am anxious to see what you come out with next.

Thank you for your kind words. You can see from my signature... I don't have as much time as I used to to create... But I do have a few ideas still.

Thanks again..
Steve

 

[Spaniard]

I switched my functioning Evercool from a NC switch to ground, to a NO switch to power the Atty.
Now I get 6.6V to 8.4V turning the Pot. This is a 200 Ohm Pot & 220 Ohm Resistor. Done BigBlues way.
I'm stuck, did I kill my TI Regulator?

 

[Jesper]

Does the pot has to be 200 ohm? I don't really like the multiturn pots and the singleturn pots in 200 ohm are a little difficult to find.

 

[rchriste]

Does the pot has to be 200 ohm? I don't really like the multiturn pots and the singleturn pots in 200 ohm are a little difficult to find.

You can use a higher valued pot with a fixed resistor in parallel with it to make it equivalent to 200 ohm combined. You can google "resistors in parallel" and find calculators for determining the values that will work for you. Somewhere in this thread I gave an example of a 1K ohm pot with a fixed resistor in parallel if you want to look for it that way. I can't remember what the example value was (what can I say... I'm a dane) so you'd have to go look for it in here or use the formula method. You're right.... there are probably more opportunities or possibilities for single turn with 1k ohm pots than with 200 ohm pots.

For one of mine, I used a 470 ohm single turn pot with a parallel resistor to bring it down to 200 ohms combined. I got the 470 ohm single turn pot from Mouser but this method will work with any value pot from any source. The one I found on Mouser has a small footprint.

 

[Jesper]

You can use a higher valued pot with a fixed resistor in parallel with it to make it equivalent to 200 ohm combined. You can google "resistors in parallel" and find calculators for determining the values that will work for you. Somewhere in this thread I gave an example of a 1K ohm pot with a fixed resistor in parallel if you want to look for it that way. I can't remember what the example value was (what can I say... I'm a dane) so you'd have to go look for it in here or use the formula method. You're right.... there are probably more opportunities or possibilities for single turn with 1k ohm pots than with 200 ohm pots.

For one of mine, I used a 470 ohm single turn pot with a parallel resistor to bring it down to 200 ohms combined. I got the 470 ohm single turn pot from Mouser but this method will work with any value pot from any source. The one I found on Mouser has a small footprint.

Thanks rchriste
I found some calculators and have no problems finding what I
But, does that mean I should change the 220 ohm resistor to the one that fits my new setup or should it still be there???
If not, to what leg on the new pot should the new resistor be soldered to?

Thanks again :*)

 

[Java_Az]

Thanks rchriste
I found some calculators and have no problems finding what I
But, does that mean I should change the 220 ohm resistor to the one that fits my new setup or should it still be there???
If not, to what leg on the new pot should the new resistor be soldered to?

Thanks again :*)

The 220 ohm resistor sets the top end of the voltage around 6 volts. A 240ohm should give you 5.5 volts. The Data sheet says to use no less then a 240 ohm resistor although most use a 220 for the 6 volt output. So yes you need to have the resistor there or you will be going way over the rated output maximum for the chip . Those voltages are with the pot turned to 0 ohms , as you turn the pot and it adds resistance the output voltage will go down. With a 200ohm pot i think the low voltage is 3.1 to 3.2 volts. So with the pot turned to 200 ohms plus the 220 ohm resistor you will have 420ohms total to give you the low voltage setting. Best bet is to solder the resistor to the leg going to pin 5 of the regulator if your following bigblues design, although it really doesn't matter what side of the pot it goes on. It might work better for you if your modifying the design to be on the other side.

 

[Jesper]

Thanks Java_Az

Ok, so all I need is another pot with a matching resistor in parallel so the total ohm will be 200.

Ex. 47k Pot + 200k resistor, should be ~200 ohm right.
And it doesn't matter to which leg on the new pot I solder the resistor to as long as it goes to leg 5 on the regulator right?

 

[rchriste]

Thanks rchriste
I found some calculators and have no problems finding what I
But, does that mean I should change the 220 ohm resistor to the one that fits my new setup or should it still be there???
If not, to what leg on the new pot should the new resistor be soldered to?

Thanks again :*)

Several people have asked about using a pot (potentiometer) with a different value than that defined by BigBlue whether it's cause they can't find the right pot or other aesthetic reasons. It is possible. You can use a higher valued pot with a fixed value resistor attached in parallel to the pot.

Here is how it will attach to your (non spec) pot. You could call it an equivalent pot circuit.



Here is a link to a calculator to determine the value of R2 (fixed resistor) based on the value of R1 (Pot) that you want to use. Any parallel resistance calculator you can google will probably work equally well if the above link becomes dead for some reason. In the above example it's assuming you want to use a 1k ohm pot. That would require a 250 ohm fixed resistor in parallel to give a total resistance ranging from 0 to 200 ohms in the equivalent pot circuit.

R1 is your Pot, R2 is the fixed value resistor you're adding in parallel and Rtotal is circuit equivalence. Just replace this circuit of (Pot and fixed resistor) for the (Pot) in BigBlues original schematic. Everything else remains unchanged.

The 220 ohm resistor you're referring too remains unchanged for this purpose. It's there to limit the maximum output voltage. It's in series with the (pot) and should remain in series with this (equivalent pot circuit). Technically.... according to the spec sheet from Texas Instruments, that 220 ohm resistor should be 241 ohms but that's picking at nits. A 220 ohm resistor is fine and works great (and is easier to come by than 241 ohms). It just means that your max output voltage will be a little higher than 5.5v per the spec sheet. It should be soldered to the same leg of the pot as in the original schematic. In the example schematic above the 220 ohm resistor would attach to the left leg and ground (pin 3 of the Ti chip) would attach to the right leg.

The wattage of the pot and fixed resistors can be 1/8 watt but if you can only find 1/4 or 1/2 watt parts they will work just as well but will take up more room due to form factor.

Whenever possible it's best to stick with BigBlues original design and schematic for the sake of the K*I*S*S method (keep it simple stupid) as this change only serves to complicate things. I would only use this parallel resistance technique if you're either desperate or determined to do so.

 

[rchriste]

Ex. 47k Pot + 200k resistor, should be ~200 ohm right.

I wouldn't recommend you go so high as 47k. It should work but I would recommend a much lower resistance pot IE 1k - 10k. You should easily be able to find a single turn pot in that lower range. Higher than that and your accuracy is going to become questionable and will require increasingly higher tolerance fixed resistors and more fluctuation due to temperature.

 

[Old_Trekee]

Got my sample from TI and was getting ready to order the other parts from Digi-Key. Got my parts list from mrengles post on page 66 of this thread. He corrected his capacitor part numbers to

Digi-Key.com

2 ....... 399-4551-ND ......... CAPACITOR TANT 100UF 10V 10% AXL ......... $3.47500
2 ....... 478-1845-ND ......... CAP TANTALUM 100UF 10V 10% RAD .......... $2.79000

However the data sheet for the PTR08100W specifically states that you should not use Tantalum capacitors on the input of the chip and only on the output if the temperature is going to be below "-20C". It also says you should use an electrolytic capacitor as well as a ceramic cap on the input pins of the chip for stability.

My question is what capacitors should I be using in this circuit? Didn't see where BB30 gave any recommendation, unless I missed it. I know he said 100uf @ 10v, but not the type. Will adding a 2nd capacitor on the input improve stability and if so, what size do you recommend?

Your help will be greatly appreciated.

 

[CraigHB]

In the data sheet, they're giving you the optimum setup to minimize ripple which is an important consideration in most applications. Since we're only powering an atomizer, we don't really care about ripple and only need it within tolerance of the regulator itself, which should be pretty liberal.

Using an electrolytic in parallel with a ceramic minimizes voltage ripple which tends to be large with a switching regulator. It's because each capacitor has different characteristics that are more effective at minimizing certain types of ripple. Ceramics are better at smoothing out high frequency stuff and electrolytics are better at smoothing out low frequency stuff. Together, they do a better job of smoothing things out.

For the application here, an electrolytic on the input and an electrolytic on the output should be fine. Tantalums are often employed to either reduce profile (they're quite a bit smaller at higher values) or becuase they have more predictable characteristics making them favorable for designs that require that sort of thing. For example, linear regulators often call for tantalum output capacitors because the chip designs can be sensitive to ESR, which is much more consistent with a tantalum. They actually do not perform any better than an electrolytic or a ceramic and are notably more expensive. Generally, you don't use tantalums unless they are called for or you have a specific need such as minimizing profile.