Mini DC-DC Step-up Converter

[ontheset]

I got this to make for a friend of mine a 5V mod. works good.

Was wondering if I can turn it into an adjustable, but i figure it will only go up to 5V?

 

[TomCatt]

I have a couple of those. I would recommend A high-drain battery (IMR, lipo).
And would definitely be interested in any thoughts on making it vv, even within 4-5V


Sent from my iPod touch using Tapatalk

 

[slimest]

Cheap booster and cheap performance. Would not recommend this for a portable systems. And also: what for 5V? Much easier to make atomizer suitable for, say, 3.2 volts taken from eGo.

 

[TomCatt]

I built a mod with this board, gave ~4 hours of flawless performance boosting a 1200mAh Trustfire 18350 batt up to ~5.2V before the inductor started to whine from not getting enough current. Even then it continued to put out 5V.

Simple and easy to use, and for ~$5, get a handful and still have enough money left over for a Pepsi compared to a dna or a Kick

just sayin'

 

[slimest]

Well, every booster and every battery works according to physical laws. If you achieved needed voltage from cheap battery as Trustfire 18350, that means that output power is miserably low, you just got voltage, not power. In any case. Because this battery just cannot give adequate power.

 

[Rader2146]

If someone that has one of these can get the part # off of the regulator chip we can look at the data sheet to see if VV is possible. I can't see the # well enough in the eBay pics.

 

[TomCatt]

Well, every booster and every battery works according to physical laws. If you achieved needed voltage from cheap battery as Trustfire 18350, that means that output power is miserably low, you just got voltage, not power. In any case. Because this battery just cannot give adequate power.

Wouldn't Ohm's Law operate for boosters also? It was actually outputting 5.1V with a 3.2ohm carto so, 1.6A & 8watts. If the voltage output is constant, wouldn't current output also be constant?
http://www.e-cigarette-forum.com/forum/battery-mods/241040-3-2-5-mod.html

If someone that has one of these can get the part # off of the regulator chip we can look at the data sheet to see if VV is possible. I can't see the # well enough in the eBay pics.

 

[TomCatt]

Responses to the cause(s) of the "whining module":

That whine means the module is starved for current and can be taken as in indication to charge the battery. 4 hours isn't so bad. With a little work you could probably get a a second battery in there run in parallel and that would take care of it, or switch to an AW IMR 18350. One of my current favorites is a 18350 IMR and the 4050 with a fixed 82K resistor to output 4.57v unloaded with a 2.7~2.8 Ω coil. What resistance are you running with this?

In my own work with DC-DC converters, I've come across several situations that can make them whine. From an engineering standpoint, it can actually be quite involved to make a converter quiet under all possible conditions.

DC-DC converters are naturally unstable so it's not a trivial matter to perfectly stabilize one of any type. It's because control has to compensate for the natural instability of the circuit and that can be a complicated thing. The goal is to make the converter "unconditionally stable".

A converter can be stable under some conditions and unstable under other conditions. For example, under various input voltages and output currents. When you run into an unstable condition, the converter may whine and voltage may fall off, but not necessarily. It's because the converter's controller is taking duty cycle from tap to tap in its failure to properly control the output. That can happen at a frequency in the audible range which results in a whining noise.

Another thing that can make a converter whine is when it hits current limiting (as determined by the controller chip). Typically, the converter resets and restarts in this case. If the converter is reseting and restarting at a rate in the audible range, it makes noise.

A converter may whine if it drops in and out of continuous and discontinuous conduction mode. That happens at the transition point between heavy and light load which is dependant on design. If the converter transitions back and forth at an audible frequency, again, you can hear a noise.

A cheap inductor can resonate in the audible range even under ideal conditions due to alternating magnetic forces on the inductor core imposed by the switching frequency and ouput load. A good converter uses the encapsulated/shielded type of inductor that is not prone to audible resonance. Those are the square solid looking inductors you see on the OKR-T and TI switching modules.

In general, DC-DC converters can be noisy things and it takes some highly detailed engineering to make them quiet under all conditions. I wouldn't expect perfection from an inexpensive converter module designed in China and purchased off eBay. You'll probably have to live with some noise or upgrade to a higher quality part like one of the Murata or TI modules.

 

[Rocketman]

Right next to the blue led are two resistors and two bypass capacitors.
Mine has 47K and 18K resistors.
This is the voltage divider that senses output voltage for the 6 pin controller chip.
The center point between the four components is easy to solder to and
there is an extra eyelet on the OUT+ tab.
I jumpered this with a resistor to drop output to 4 volts.
Regulates well at 4 volts.
VV could also be done here.


Going over 5 volts will reduce amps out. Max power exceeded as well as peak current through Mosfet (it's shunt connected, not a pass transistor). The board would make a nice 3.7 to 5 volt VV with about 3 amps out. I guess if you removed the 47K resistor and put a 30 to 50 K adjustable resistor (30 k fixed in series with a 20k pot) that would make it VV, about 3.7 to 5.2V.


Sorry, but making a 6 volt VV mod for 1.5 ohm DCC won't happen with this board without changing the Mosfet and the Schottky diode.

 

[TomCatt]

Thanks for that info, Rocket. If I ever feel adventurous I may try vv'ing one of these. 8 watts is plenty enuff for me, have had no desire to even try vaping my ADV at 24 watts


Sent from my iPod touch using Tapatalk

 

[ontheset]

How about this one?

10Pcs KIW-3312S Dual Way Output Power Module New | eBay
http://we.easyelectronics.ru/part/sdvoennyy-preobrazovatel-napryazheniya-kiw-3312s-ir3802a.html

I have found this database with a lot of s**t.
http://category.alldatasheetcn.com/index.jsp?components=CONVERTERS Step-Up

Maybe someone can take the time and find treasure.

 

[Rocketman]

I was asked about more details on the changes needed to make this little boost board VV.

The only one I have is already installed in a tube mod, but what I found before I sealed it up was that 5.1 volts loaded at 2.5 amps was about the upper end and 3.7 was the lower end. I believe trying to run this type of board higher than 5.1 volts and loading it out of regulation will end up being destructive. There may be some devices out there where you set them at 6 volts then load the heck out of them with a lot less than 6 volts going out under load. When a boost circuit maxes out and the voltage falls, that is obviously out of the design operating range.

The same holds for the lower end. With 3.7 volts out, the series schottky diode will drop about 0.3 - 0.4 volts under load. The voltage before the diode will be about 4.0 under load with a FRESH Li-ion cell and fall lower. The boost circuit will run with 3.7 volts set as an output. Set it any lower and the boost circuit doesn't start. Just series conduction through the inductor and diode. The efficiency at lower voltages suffers because of normal resistive loses and the diode losses.
For example, at 4 volts, 2.5 amps out, the diode drops .4 volts. About 10% of the energy is just plain lost in the diode. At an output of 5V, the 0.4 volt drop the loss in the diode is only 8%.
Draw more current, drop more through the diode.

So, back to making this VV.
The voltage divider is connected between the + output and the common (both in and out) ground. The center tap of the divider goes to the controller chip (little 6 pin one).
The safe range for this resistor seems to be from a high of 50K ohms(5.2V) to a low of 30K ohms (3.7v). Probably the easiest way to accomplish this would be to cut the 47k resistor out and solder a small 30K ohm resistor to the junction of the 4 parts shown in the pic I posted. A 20K ohm potentiometer would be connected between this new resistor and and one of the spare +out eyelets on the board. This would give a range of 30K to 50K ohms instead of the original 47K ohms.

I'm not good at making those 'picture' schematics, maybe someone could post one of those from the description I've given.

I do have a couple more of these boards coming (slow boat) and could try this again and post pictures if anyone needs more help.

 

[asdaq]

Just a couple of words: Current matters.

 

[perlionsmitnick]

Here is the original schematic.

 

[Rocketman]

That's a dual buck regulator. The eBay ad says 10 ea. which I will check out to make sure.

The IR3802 has an internal fet and the specs say 6 amps.
A quick look and it looks almost like the board could be cut in two with only a
couple of run repairs.

With a change in the voltage divider it looks like it could make a really cheap buck regulator (if in fact the price is for 10).

Interesting.


The OK-R 6 amp buck module is smaller. I put one in an eGo tube and wired as a car pass through. But it's about $7.


But, we have gotten off topic

 

[ontheset]

So i guess you can easily make a dbl mod with 2 different voltage outputs, like a LR and a HR.
That would be neat

 

[Rocketman]

I got a reply back from the ebay vendor for the KIW-3312S modules.
"The Package Included 10X power module"

So, I ordered them. If they work that's less than a dollar each.
There seems to be a couple vendors selling these.
Wonder what they were used in?

Since they will be coming by slow boat I will try and let you guys know how they work, hopefully before Christmas

Remember that these are Buck converters not Boost.
The specs for the controller used is up to 0.8X Vin.
Running a pair of cells down to 3 volts each would mean an output of 4.8 volts.
Stopping at 3.3 volts loaded would give 5.28 volts.

 

[ontheset]

Cant wait