Easy OKR-T VV mod

[CapeCAD]

I follow.

And it will always cut off by the time the cells get to 6 volts. That's safe (the main issue, right ?).

but if the cells are 6.5 volts, the voltage drop across the zener puts 0.9 volts at the control pin, right?

That's in the "undefined logic state" of 'will probably fire'.

In order to get 1.5 volts "the spec ON voltage" with a 5.6 volt zener you would need 7.1 volts from the cells.

This seems to be in the "works most of the time" category.

But, you are probably right because I'm sitting in front of the computer, and too lazy to go see for myself

Rocketman, I think you got this all backwards, or atleast your zener thinking.

When reverse voltage exceeds the breakdown voltage, the full voltage will be applied to the pin. When voltage is lower than the breakdown voltage no voltage will be applied to the pin and the pull down resistor will bring it below .4V

There will not be a voltage drop across the diode since you are reversing it to use the unique resettable breakdown properties of the zener diode.

 

[mamu]

I tested using a DC Power Supply. At 6v it doesn't fire and above 6v it fires.

ETA: thanks for the explanation Cape.

 

[Rocketman]

Rocketman, I think you got this all backwards, or atleast your zener thinking. When reverse voltage exceeds the breakdown voltage, the full voltage will be applied to the pin.

Ever use a zener as a shunt regulator? Zener reverse voltage is just that.
Imagine what would happen when it started regulating
But if it works fine.

 

[CapeCAD]

Ever use a zener as a shunt regulator? Zener reverse voltage is just that.
Imagine what would happen when it started regulating
But if it works fine.

Of course, hasn't everyone?

If you want to read up more on this Figure 7 on page 10 of this datasheet will explain it all, that's where I got the idea from originally.

 

[Rocketman]

Is that the correct link?



All I am saying is the OK-R spec says it will positively absomlutly turn on when the control pin gets to 1.5 volts. and will turn off if control pin voltage goes below 0.4.
It may not change states in the zone between that.

The Zener idea in the circuit is a great idea.

Here's how I think a zener works.

 

[CapeCAD]

Is that the correct link?



All I am saying is the OK-R spec says it will positively absomlutly turn on when the control pin gets to 1.5 volts. and will turn off if control pin voltage goes below 0.4.
It may not change states in the zone between that.

The Zener idea in the circuit is a great idea.

Here's how I think a zener works.

??=6.4V or 12V-5.6V

I understand what you are saying, and you bring up a good point as converter is enabled and voltage drops below UVLO it is unclear exacly when it will turn off between .4 and 1.5V (I believe .4).

Yes, that is the correct link with an explanation of how the zener works for UVLO. The theory is applicable to pretty much any controller with S/S pin. The resistor needs to be adjusted for proper shutdown voltage which Mamu was able to work with 10k.

 

[meatsneakers]

Just wanted to post my findings about using batteries in series with this OKR mod. I made a pack from 2 14650 IMR cells in series, and sealed it with heat shrink after about 2 weeks of onboard charging just to keep them away from juice.

It's now 4 months later and my mod fell and part of the body cracked so I decided to gut it for the time being (I have another OKR mod I've been using the past few weeks). Anyway, I tested the batteries and both were at 3.99v, on the dot, with two multimeters. Runtime has been just as good as when I first built the mod and I've recharged them probably around 250 times from half capacity (~7.4v).

 

[mv2envy]

My batteries are always within .01V of eachother when I take them out to recharge them.

 

[k3vin]

marking a spot

 

[meatsneakers]

My batteries are always within .01V of eachother when I take them out to recharge them.

That's usually the case with my mods that have removable batteries. It just surprised me that they held so close after months of being charged as a pack with no balance circuit.

 

[Todd Mulske]

I have a question. I see you are using a .6 watt resistor between your .5 watt potentiometer wiper and the adjustment/output trim contact on the voltage regulator. I understand that at 200 ohms the output voltage will just be slightly over 6 volt max. My question is this; would it work to put a .5 watt resistor between the trim and potentiometer and go with a larger potentiometer watt rating like 2 watts. Does the potentiometer draw power out of the trim contact on the voltage regulator at its rating say 2 watts. If so it would make sense to say that a 2 watt Potentiometer would fry a .5 watt resistor. The opposite would seem true that if you used a 2 watt resistor with a .5 watt Potentiometer you would take a risk of frying the Potentiometer. So lets say you wanted to go with a 2 watt potentiometer; would you then need to go with a 2 watt resistor between the Trim and the Potentiometer. Thanks for the diagram.

Todd

 

[bstedh]

The trimmer circuit does not carry any load which means that a high wattage is not needed. The Atty load does not run across it in any way. It is a control portion of the circuit with very low amp draw.

The only high amperage area in the circuit is between pins 2 and 4 of the regulator.
Pins 1,3,and5 are low amperage.

I have a question. I see you are using a .6 watt resistor between your .5 watt potentiometer wiper and the adjustment/output trim contact on the voltage regulator. I understand that at 200 ohms the output voltage will just be slightly over 6 volt max. My question is this; would it work to put a .5 watt resistor between the trim and potentiometer and go with a larger potentiometer watt rating like 2 watts. Does the potentiometer draw power out of the trim contact on the voltage regulator at its rating say 2 watts. If so it would make sense to say that a 2 watt Potentiometer would fry a .5 watt resistor. The opposite would seem true that if you used a 2 watt resistor with a .5 watt Potentiometer you would take a risk of frying the Potentiometer. So lets say you wanted to go with a 2 watt potentiometer; would you then need to go with a 2 watt resistor between the Trim and the Potentiometer. Thanks for the diagram.

Todd

 

[erich]

Admittedly not the prettiest... I didn't do a very good job of planning the wire wad, but for my first mod, I'm liking it.

 

[erich]

Note to self: be sparing with epoxy around the on/off switch.

Pot & fire button are fine, though.

 

[bstedh]

Good way to jump into modding with both feet..

 

[Harrygrowth]

Mine's basically a wiring disaster. But it works! I leave the pot inside the box. Doesn't get bumped.

 

[Quigsworth]

(sorry if this has bee asked/answered already)...has anyone used the Madvapes LED volt meter on this cct? I've got a couple coming and I have a bit more real estate in my box than I thought...I here they tend to just flicker on some regs?

 

[CapeCAD]

(sorry if this has bee asked/answered already)...has anyone used the Madvapes LED volt meter on this cct? I've got a couple coming and I have a bit more real estate in my box than I thought...I here they tend to just flicker on some regs?

It worked fine for me. I've never seen them not work with any converter myself.

 

[Quigsworth]

Thanks for getting back so quick CapeCAD, I was just racing back to do an edit cause I decided to NOT be my usual lazy self and actually read all the posts <<hangs head in shame>>...

I'll be posting pics of mine soon. I went with the smallest Otter box which still lets me run 4x 18350's "and" totally recess the atty, or in my case my fav to date, the Smoktech eGo dual coils (PITA to build the batt conn for those eGo products though)

 

[YUzazaMY]

I have all the parts listed in the first page and just waiting for OKR-T/6-W12 cip to arrive. My problem is I dont have a 200 ohm 0.6W resistor. Can I just use 200 ohm 1/6W resistor that I already have? or
what is the resistor value to replace the 0.6w resistor if I have only 1/4W, 1/6W, and a 1 ohm 2W type of resisitor to choose from? This is the only of resisitor that my local store have.

My local store have a 200 ohm trimmer pot but the only difference that i can see from the description between the 3352T-201LF--ND Variable resistor is it only have 10% Resistance Tolerance rather than 20% Resistance Tolerance that 3352T-201LF--ND have. Can I use that trimmer pot?