Homemade 3.7 volts passthrough question...

[surfsuphere]

As you above clearing know something about electronics, and I also spend a great deal of time in office chair, or living room chair and within FEET of basic electrical outlet; what I had been searching for is a PT that simply plugs into wall with a voltage regulator of some type and no need for an inline battery.

Is this possible?

 

[CraigHB]

Seems like there's a bit of a demand for a wall powered battery-less VV passthru.

I was thinking you could make one with a 12V wall wart and the buck regulator used in the Evercool mod. Pretty easy to do actually. Just a little box with a barrel receptacle on one end and a USB on the other, put a dial in the middle, maybe a voltmeter too.

I'd go with the higher voltage on wall wart to get the most current capacity on the output. Also, at 12V, you could also use it with a cig lighter adapter. 12V 2A wall warts are cheap on ebay; like this one.

 

[AttyPops]

Yeah, but at that point, why not just use a vv power supply to begin with? Also, see post #17.

CraigHB, where was that self-made booster? Is there a simple voltage boost or voltage doubler method? Or do we end up with a module? Other than post 21, which just repeats the questions already discussed in the whole thread (yeah, high demand).

Seems like voltage doubling is a common thing in electronics. Also, a switching regulator on a voltage doubled 5v USB connection (even if using 2 inputs for the amps) would be easy... I would think less expensive, but IDK. Remembering that USB is a 5v standard. I totally agree with the 12 v (or even 9 v depending on output range) PS points.

I think you had a post about it... maybe with $$$ and comparison. Can't find it.

Bet it can be done with RLC or LC real easily.

 

[AttyPops]

As you above clearing know something about electronics, and I also spend a great deal of time in office chair, or living room chair and within FEET of basic electrical outlet; what I had been searching for is a PT that simply plugs into wall with a voltage regulator of some type and no need for an inline battery.

Is this possible?

There's a ton of examples for this in this section for 5v PT. If you want other voltages, or vv, that's what this thread is about.

 

[CraigHB]

Yeah, but at that point, why not just use a vv power supply to begin with? Also, see post #17.

True, the VV battery-less passthru I use myself simply employs a VV power supply like you suggested. I was just thinking in terms of something smaller and lighter. I haven't seen any off-the-shelf VV power supplies that are cheap and compact, any links?

CraigHB, where was that self-made booster? Is there a simple voltage boost or voltage doubler method? Or do we end up with a module? Other than post 21, which just repeats the questions already discussed in the whole thread (yeah, high demand).

I mentioned it somewhere, but I don't recall. Anyway, what I've made for myself is simply a boost converter using the chip shown in my avatar. It sits on a board with other chips (charging, control). The low profile of a single one-sided board is mainly why I don't use the POL modules that are so popular, but those modules and the charging ones are the cheapest, easiest way to put together a full featured mod. Also, I want to use single cell boost and I haven't found any boost modules higher than 12W. The one I built myself can output 30W (measured).

The new mod I'm doing may use a buck-boost controller. I haven't decided yet. The advantage of buck-boost with a single cell is you can go below battery voltage, but I'm debating whether it's worth the trouble. I mean how often do you want to vape at 3.5V or something. I rarely have a desire to go below 4.0V myself. If I can find a controller with built-in FETs and high enough output it might be worth it, but otherwise, 4 external FETs makes things a lot more involved. There's other ways to do buck-boost without using a self-configuring controller, but I've already decided that's the best way to do it. I've tried, and I just can't get the efficiency I want out something static like a SEPIC or flyback converter.

The best configuration for a wide voltage range is dual batt (or a batt pack) with a buck regulator, but it complicates on-board charging. I haven't come up with a simple, compact solution for that. If I ever come across something or come up with something myself, I'll likely give it a go.

Seems like voltage doubling is a common thing in electronics. Also, a switching regulator on a voltage doubled 5v USB connection (even if using 2 inputs for the amps) would be easy... I would think less expensive, but IDK. Remembering that USB is a 5v standard. I totally agree with the 12 v (or even 9 v depending on output range) PS points.

Yes, charge pumps or doublers are often used for things like LCD biasing and driving FETs. They're capacitive instead of inductive. The problem is that power output is generally not near high enough to do any real work. I imagine it would be possible to make one that puts out a fair amount of power, but I've never thought about it. Would probably require some large and expensive components.

 

[VpnDrgn]

@craighb "The new mod I'm doing may use a buck-boost controller. I haven't decided yet. The advantage of buck-boost with a single cell is you can go below battery voltage, but I'm debating whether it's worth the trouble. I mean how often do you want to vape at 3.5V or something. I rarely have a desire to go below 4.0V myself. If I can find a controller with built-in FETs and high enough output it might be worth it, but otherwise, 4 external FETs makes things a lot more involved. There's other ways to do buck-boost without using a self-configuring controller, but I've already decided that's the best way to do it. I've tried, and I just can't get the efficiency I want out something static like a SEPIC or flyback converter."

I found this step up - step down converter, but it is only spec'd for 300ma. datasheet

Is there something than can be added externally to get it up to the required amps?
Or maybe, redesign it to handle more amps?

I talked to the vendor about some of the parameters we need in regards to a board with this function.
They simply said they didn't have a board to meet our requirements. I am sure the mnf could probably
make the board we need but there is no market. All the pre-made boards are used in stuff that just
doesn't need the amps that we do, and I'm sure the mnf would want a lot for D&D.

 

[AttyPops]

...... mnf would want a lot for D&D.

Dungeons and Dragons? lol. JK

Wonder if you could double/triple/quad them.

Yeah, and the boosters often don't have the range we want either. Fixable, but still. PITA.

The best configuration for a wide voltage range is dual batt (or a batt pack) with a buck regulator, but it complicates on-board charging.....

Sorry, no PSU links.

Yeah, that's what I use with batteries, more or less, but this is about a PT and mains AC->Adapter->PT so efficiency is less of a concern, and more about getting voltage range for the regulator. The points about just using a higher voltage AC adapter are well made. However, since USB is a 5 volt standard, and we all have tons of AC wall-wart links, I was asking about voltage doubling. IDK. Maybe just a bad idea all the way around. Probably why we don't see em made commercially.

The new mod ur working on sounds cool. I personally think 2 14500s are worth using vs, say, a 18650 boosted. Just easier and less fuss. But I'm not you, and can't design that stuff. Sounds fun.

 

[CraigHB]

I found this step up - step down converter, but it is only spec'd for 300ma. datasheet

That one is a SEPIC converter (single ended primary inductance converter). The problem there is SEPICs really start choking on efficiency when you get into the higher output currents. I believe it's due to losses when using a coupled inductor. You can design a SEPIC with two separate inductors instead of one coupled inductor, but then you get big losses on the more heavily loaded passthrough capacitor. I tried building one myself and I couldn't get it over 80% at 10W. A better engineer than me could probably get that a little higher, but I'd be surprised if it's possible to see much over 85%. It's just the nature of the beast when using coupled inductance I think. Aside from that, SEPICs are really hard to stabilize when using the higher inductance values, lower frequencies, and lower ESR values required to make them more efficient at higher currents. They have several zeros in their frequency response that move into the unstable right hand plane when designing them for higher efficiency at higher outputs. Ick, analog stuff.

The best buck-boost to use would be an inverting buck-boost converter, just a switch, inductor and rectifier. Very simple and efficient just like a buck or a boost regulator, but can go above and below input voltage. Though no one makes a controller for that since the output is inverted, not very practical to output negative voltage at high power. You could use one on an atomizer though. It doesn't matter for that. If I could get a controller like that, it's what I'd use.

 

[VpnDrgn]

Uhmm.. Sorry, most of that went over my head.
Efficiency aside, I take it there is no way to use this and get it to handle the necessary amps?

 

[CraigHB]

Sorry, I guess I failed to answer your question.

No, there isn't a way to modify that unit. Anytime you use a a modular switching regulator, what you get is what you get.

BTW, here's a little chart that provides a concise run-down of all the differnt types of switch mode regulators.

 

[VpnDrgn]

Thanks Craig,
I tend to space out a bit when all you gurus start using the tech-speak. I am always on the look out for better
modular units because they are more my speed. I can focus more on design of the mod and not the guts.
I am prolly gonna try Breaktru's booster version because I already have the 4050C boosters, but that
is prolly as close as I'll get to building my own circuits.

 

[WillyB]

@craighb "The new mod I'm doing may use a buck-boost controller. I haven't decided yet. The advantage of buck-boost with a single cell is you can go below battery voltage,

I think you got that wrong, the boosters need to boost, they don't step down.

Look at the TI 04050, in the specs all the voltages are 5+V. That's why folks throw diodes on them to knock down the output.

As you above clearing know something about electronics, and I also spend a great deal of time in office chair, or living room chair and within FEET of basic electrical outlet; what I had been searching for is a PT that simply plugs into wall with a voltage regulator of some type and no need for an inline battery.

Is this possible?

You willing to build one? I could post a simplified and inexpensive setup with parts list. It would top out at about ~5-5.5V (hard to tell till you actually try it).

 

[CraigHB]

When talking semantics about buck-boost, there are several different topologies to consider. An inverting buck-boost topology doesn't really do either in the buck or boost sense. Rather, it outputs voltage from zero to negative something purely as a function of duty cycle. Other buck-boost topologies like SEPIC and Flyback do the same thing, but uninverted. With these topologies, there's no offset based on input voltage like there is with a purely boost or a purely buck topology. It's sort of a misnomber to call these topologies buck-boost converters, but they're called that anyway.

Conversely, Linear Technology offers a line of buck-boost controllers that really are buck-boost controllers in the true sense of the term. They use 4 FETs to switch back and forth from buck to boost mode. That's a physical change in topology the circuit is performing, very trick.