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Breaktru Forum  |  eCigarette Forum  |  Modding  |  Topic: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
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Author Topic: Tinkering with the OKL2-T20 20A 110W dc/dc converter...  (Read 145042 times)

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Offline cburnet91

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #200 on: July 02, 2014, 03:52:33 AM »
it works fine with a 1.4 ohm single coil on my trident rda but on a .5 ohm dual coil on my crown is when I get the voltage constantly dropping.
it never fires passed 4.6 then goes all the way down to 3.6 very fast then the voltage reader starts flickering. I also noticed that it doesn't go
all the way down to 3.5, its more like 3.6 and only goes up to 5.2 volts. Could it be the battery holder im using. I'm also using the pre soldered thin wire
that's already on the battery holder. Thanks for all your help by the way. Sorry for so many questions.

Offline cburnet91

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #201 on: July 02, 2014, 04:27:37 AM »
Also, are the sense connections necessary and if so should I use 24 gauge for that also

Offline CraigHB

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #202 on: July 02, 2014, 04:52:37 AM »
Could it be the battery holder im using.

Probably.  You need a solid connection to the battery when using more power.  The cheapo battery holders with the 24 gauge wires are not going to cut it.  Likely the wires are overheating causing big voltage drops and then the controller board conks out due to low input voltage.  More power requires more heavy duty wiring and connections, there's no cheating on that.

Offline cburnet91

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #203 on: July 02, 2014, 05:14:29 AM »
So in theory replacing those I'd say 26 gauge wires with 16-20 gauge should make an improvement if not fix the issue. Anyone know the lowest ohms this board can go.
Its a 20 amp chip so i'm guessing around .3 at 5.5 volts?

Offline cburnet91

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #204 on: July 02, 2014, 06:33:57 AM »
So I made my own battery holder using brass for the contacts and soldered 18 gauge wire to it and the voltage is not dropping. So far so good. Not noticing anything gone wrong through the circuit beside the 510 (fat daddy vapes spring loaded) getting hot when firing at high volts for extended periods testing but I'm sure thats from the atty getting so hot.
Man this thing chucks the vapor. Only thing left to figure out is why my minimum voltage is 3.6 and highest is 5.28-5.3

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #205 on: July 17, 2014, 08:28:41 PM »
Hello, I'm new to the forum and wondering if anyone can help me. I am working on my build however it is autofiring so I check the 20K resister as I read here that that is the most common issue. When I check it with a meter it reads 14.7K and when I check a brand new one it reads 19.8K. I believe the 19.8K is ok but what would make the one in my test layout read 14.7K? ANy help would be great.

Thank You.

Online Breaktru

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #206 on: July 17, 2014, 09:21:02 PM »
I check the 20K resister as I read here that that is the most common issue. When I check it with a meter it reads 14.7K and when I check a brand new one it reads 19.8K. I believe the 19.8K is ok but what would make the one in my test layout read 14.7K? ANy help would be great.

Thank You.

Welcome to the forum.
Did you check the 20k out of the circuit and not in the test layout?

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #207 on: July 17, 2014, 09:23:54 PM »
No not yet. I am removing it right now. Will let you know.

Thanks for the quick response.

Thank You.

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #208 on: July 17, 2014, 09:50:44 PM »
Off the circuit it reads 19.1K

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #209 on: July 17, 2014, 09:51:27 PM »
Sorry 19.9K

Offline CraigHB

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #210 on: July 18, 2014, 05:19:10 AM »
I believe the 19.8K is ok but what would make the one in my test layout read 14.7K? ANy help would be great.

A 1% 20k resistor can range between 19.8K and 20.2K and still be within tolerance, so your resistor is good. 

You typically can not get good readings on a resistor when it's in a circuit because there may be other paths for the current to follow creating a parallel resistance.  In some situations you can get a good reading with a resistor in-circuit, other situations you can't, just depends on the circuit.

You have to check resistors before you install them.  The only thing that damages them is an overload so once a properly rated resistor is installed, it's good for the duration.  Active components like transistors can fail and passive components like capacitors can fail, but it's almost unheard of for a resistor to fail.

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #211 on: July 18, 2014, 09:07:28 AM »
Thanks Craig,

So now that we know the resistor is good  any ideas on why it was autofiring? My assumption is that I had a bad connection between pins 1 and 2 with the resistor. My next step is to go back to breadboard and see if I can put it all together (again) and test from the breadboard. I started straight out of the gate putting it together mainly because I read about the volt twilight zone readings the breadboard was causing. But my thought is that if I go back to breadboard and it all works I can then start soldering it down again.

Offline mamu

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #212 on: July 18, 2014, 10:51:59 AM »
Either the resistor had a bad connection at Vin and/or at on/off for the OKL2 to be auto-firing or you have the positive logic OKL2 (OKL2-T/20-W12P2-C).  I worked with the negative logic version (OKL2-T/20-W12N2-C) which requires a pull-up resistor from on/off to Vin.  The positive logic version needs a pull-down resistor from on/off to ground.

...Only thing left to figure out is why my minimum voltage is 3.6 and highest is 5.28-5.3

With a 1K pot plus 1.43K resistor you should have a range of 3.5v - 5.5v depending on the tolerance of the pot and resistor.

If you have a 1.43K resistor 1% tolerance connected between +Trim and an outer leg of the pot, you should be getting 5.5v output when the pot is turned all the way to 0 ohms.

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #213 on: July 18, 2014, 10:58:50 AM »
Thanks Mamu,

I did recheck my mouser order and this is what I received OKL2-T/20-W12N2-C. So I guess the on/off - vin had a bad connection. I will update once I breadboard and see if I can fire with the button.

Offline mamu

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #214 on: July 18, 2014, 11:10:44 AM »
Just a thought - are you using the N-FET at on/off?  Did you make sure to put a 1K resistor across gate and source?  Without that pull-down resistor the fet won't turn off and the converter would auto-fire.
« Last Edit: July 18, 2014, 11:15:21 AM by mamu »

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #215 on: July 18, 2014, 11:41:24 AM »
I did use the n-fet and had the resister there.

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #216 on: July 19, 2014, 12:20:49 AM »
Thanks for all of your help. It must have been a bad connection at the 20K because I rewired everything onto my homebrew PCB and wired it all up and PRESTO....... BOOM..... (Edited for Craig ;bow;) we have vape. Now time to put it in the box.

Thanks again for all of your help. WIthout people like you I would never have even attempted this. Kinda strange my first Box MOD is going to be a 100w monster......

Thanks again :)
« Last Edit: July 19, 2014, 03:10:05 PM by BFBCAcid »

Offline CraigHB

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #217 on: July 19, 2014, 03:33:00 AM »
Oh man, don't say "BOOM" when talking about e-cigs, I thought you were about to say your battery exploded, anyway, good to hear all is well.

Offline Visus

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #218 on: July 19, 2014, 05:55:18 AM »
Woot  glad you accomplished your goal

Great build up to success,  I also thought %&^*..

OT mouseover

Craig I always say boom,  yeah direct short makes no sense to noobs but when you have seen a hefty 15A short blow a hole thru steel no other word will get across to people who have no idea how much energy  are in these e cigs..  30A whoa  60A OMG

Yeah the media loves that word so I guess I could say, you may have a horrible outcome and  need hospital services if you proceed  :laughing2:

IDK maybe ill not say anything anymore and let it be.. 

As a journeyman we yell and bully our know it all helpers into knowledge, one freakin mistake can take out a whole splicing chamber of people when dealing with live 32k amps.  It has happened, very rare, (good training) but--it blew the clothes and skin off a coworker, he luckily lived to talk about it.  The fireballs luckily went str8 up about 200ft,  a train unfortunately was in the system drawing ~15k amps 600vdc, if two trains 32k, it had stopped about 60 ft from it and the breaker kept resetting and the fireball kept booming until control  shut it down from their board..  My co worker had made a huge mistake and was caught in a splicing bunker with the million5 (MCM5)  shorted to structure on the elevated system,  he was frying and made the decision to jump to his demise, another co worker hero'd, he moved the line wagon under him and had started raising the platform before he was under him,  he fell about 4ft onto the platform..  Whats wild,  our platforms usually wont raise from the trucks inside controls in gear,  this truck was broken and the tower and outside controls busted and it should have only worked from the inside controls in park, it had worked while in gear.  Miracle oh yes..  No other linewagon works this way,  it was in the waiting line to be serviced for repair.  This was  about a window of ~15 secs of movements.  Another wild addition to this story,  a news crew was filming a story at a restaurant next to where it happened and caught the whole incident.  Its used to this day (1987') as an industry wide training video of what will happen..  Horrible video but he lived..  The hero co-worker just knew the tower would raise and it did he said he didn't even think about it as it would not.. 

A touche to this story,  the linewagon was fixed and a month after it was fixed the tower raised on its own going under a bridge sending the chauffeur to the hospital for years.  It was retired lol...

No time for mistakes or inaccuracies and we put these things next to our faces. :laughing:

Offline CraigHB

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #219 on: July 19, 2014, 10:17:40 AM »
No time for mistakes or inaccuracies and we put these things next to our faces.

Yeah, it kind of puts a whole new spin on safety.  It's one thing for a battery to explode on the charger, another if it happens in your face.

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #220 on: July 19, 2014, 03:13:07 PM »
Safety is no joke and everyone (including me) needs to consider that when dealing with power. Education is a must and knowledge is POWER. Edited post to ensure no one else gets the wrong idea.

Thanks Again.

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #221 on: July 20, 2014, 11:38:06 AM »
Thanks to you all I now have my mod just about complete and was wondering if using a 11.1 Lipo battery would be acceptable for this build? I did read the specs on the OKL2 and it says "Operating voltage range Minimal 4.5 Volts, Typical/Nominal 12 Volts, Maximum 14 Volts,". The reason I ask is I fly RC Helicopters and have about ten (10) 11.1v Lipo batteries, 2 6S Balance Changers as well as a slew of other Lipo batteries and connectors. I like to use Lipo whenever possible because of it's power to weight ratio and just because I am set up for them it makes things easier for me. As always thanks again for your input.

Thank You. 

Offline CraigHB

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #222 on: July 20, 2014, 01:40:10 PM »
Yes, you can use a 3S LiPo if you like.  Though the 60C ones are pretty volatile.  It's safer to use the 20C ones.  The higher the drain limit the faster they release energy if a fault condition occurs.

You must have some kind of short circuit protection when using a LiPo.  Since the OKR-T/10 provides current limiting and overload protection, you should be covered.  Ensure your wiring is sound and no internal faults can occur there.  Even so a fuse is never a bad idea as a backup.

Generally the round cells are safer than the LiPos for a few reasons.  For one, LiPos are only encased in a thick foil where the round cells are encased in a steel tube.  This makes LiPos vulnerable to physical damage which is much more hazardous in terms of exploding cells than a short circuit. 

Another reason the round cells are safer is because the high drain ones use a less volatile chemistry than the LiPos, that is Lithium Polymer versus Lithium Manganese.  A fault is less likely to cause "thermal runaway" which is the technical term for a cell catching on fire and blowing up.  If thermal runaway does occur, the reaction happens slower.

Since round cells are typically used for personal electronics where the "S" LiPos are typically used for RC models, a lot of R&D is put into the round cells to make them generally safer in terms of their volatility and failure rates.  Little effort is put into the hobby LiPos to make them safer. 

Comparing chemical volatility, LiPo is safer than LiCo, but more hazardous than LiMn.  The drain rating also has an impact there since it determines the maximal rate the cell can release energy.

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #223 on: July 20, 2014, 05:42:06 PM »
Thanks for the info. I do have a fuse at the batt and it is a 20c rated 3S.  Also I made a PCB for the layout and only have wires where absolutely needed I hope this will minimize wiring mishaps. I was concerned about stressing the other components but I think by what you are telling me I should be ok there. I may give it a shot and watch it for a while to see if it performs as expected.

Thanks Again.

Offline werkkrew

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #224 on: July 21, 2014, 10:39:50 AM »
I have a question about the primary diagram in the OP.

In browsing the entire thread I have seen some separate diagrams which included reverse polarity protection, low-voltage cutoff, and a low voltage LED indicator. 

Are these integrated into the main diagram right now?  They appear to be but I am not 100% sure.

Also, what does the switch in this circuit need to be rated at?


Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #225 on: July 21, 2014, 11:37:37 AM »
I have confirmed that using the current diagram there is reverse polarity indicator light. As well if a zener is used then there is also low voltage cutoff. Also I believe I read through this forum that the switch needs are very low due to the fact of it's placement and that the master switch if used only stops it from firing and does not turns off the system and idle drain still occurs. Please feel free to correct me if I am wrong here .

Thank You.

Offline zotek

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #226 on: July 22, 2014, 02:27:19 AM »
Juicy - I used these on my OKL2.  Used a 2.2k ohm pot and 1.43k resistor for the circuit, gives right around 2.5 - 5.6 volt control. Looks very similar to the Axiz mod pot, works great, fantastic quality, will be using them in all box modes that I make in the future, both for my own and for others!!

Yes they are pricey.

http://www.digikey.com/product-search/en?v=716&FV=fff40004%2Cfff80335&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

Parts list for my 20amp mod:
http://www.digikey.com/product-detail/en/P16NP222MAB15/P16NP-2.2K-ND/1587862
https://www.fasttech.com/p/1258801



http://www.fatdaddyvapes.com/shop.html (The new one with 22mm washer)
Radio Shack switch :P
1.43k resistor
4x22u caps (2 input, 2 output)
20 gauge
On/Off slide switch

No screen, no reverse polarity protection, no voltage cut.  Some of the better modders may be able to fit it in that box, but I could not. Great mod for myself, but wouldn't give to anyone else.

What amazes me, is that at 3.7 volts my Kayfun hits easily as hard as it does off a Penny Mod (pure copper mech with the lowest recorded drop) using a fresh charged VTC-5!  In fact, the only tank I have that can consistently wick fast enough over 4 volts is my Expromizer.  .69 and .74 ohm builds respectively.  VV mods have now replaced all my mechanicals! 

After typing the above I decided to try my Stillare at .28 ohms dialed up to 5.5 volts........ really bad idea raged:


can you please post your guide? because i wanna setup the same thing..why do u need output caps? thanks

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #227 on: July 23, 2014, 12:34:39 PM »
I was wondering if someone could help me with a change I would like to see in the OP for my own mod? When the 3 position switch is set to VIN it turns on the LCD and displays the current Battery Voltage (VIN) and stays on. However, when I change the 3 position switch to VOUT nothing is displayed until I hit the fire button. I was wondering how difficult it would be to turn on the LCD when selecting VOUT so that you could see the voltage set by the Pot? If I have something wired wrong or this does not make sense please let me know and I will do my best to clarify.

Thank You.

(Edited) I don't want the OP to change just wanted to say that I used the OP for my mod so that is what I have currently.
« Last Edit: July 23, 2014, 12:40:48 PM by BFBCAcid »

Offline Visus

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #228 on: July 23, 2014, 02:11:37 PM »
Theres literally no way without using a digital pot/controller and mcu/oled/etc to show you the v-out voltage set or  change acid.

Totally seperate setup. 
Even clavigers fancy arduino setup wont until you pulse the atomizer then of course it will every fraction of a sec display and keep that on the screen but thats just the last pulse, its a picture of vout  when you vape again it may change..  A  build like Craigs will do what you want and it will stay put but yeah very difficult.




Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #229 on: July 23, 2014, 02:20:04 PM »
Thanks for the quick reply. Sounds like it is what it is.

Offline Visus

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #230 on: July 23, 2014, 02:28:37 PM »
Yup it needs a brain. 

Offline CraigHB

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #231 on: July 23, 2014, 04:05:37 PM »
A  build like Craigs will do what you want and it will stay put but yeah very difficult.

Yes, the atomizer data is "sticky" for my mods.  But that also brings a point of contention.  You have to power the atomizer to get a new reading.  Not a big deal, a quick tap on the trigger will do, but still there's not really an on-demand option for checking resistance.

In any case to get stored readings, you have to use a device to store data.  The one and only way to do that is with a micro-controller and all the business that involves using one.

Offline zotek

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #232 on: July 23, 2014, 11:03:42 PM »
can please someone help me.im building a box but i dint want to use fuse,reverse polarity LED lights..can someone post  wiring diagram? and part needed ?thanks

Offline mamu

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #233 on: July 24, 2014, 05:05:06 AM »
can please someone help me.im building a box but i dint want to use fuse,reverse polarity LED lights..can someone post  wiring diagram? and part needed ?thanks

If you're not going to add a fuse or p-fet, wire Vin to the batt + contact on the batt holder.  If you're not going to use the n-fet, wire on/off control to one leg of the fire switch and wire the other leg of the fire switch to ground.

Offline zotek

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #234 on: July 24, 2014, 09:44:02 AM »
If you're not going to add a fuse or p-fet, wire Vin to the batt + contact on the batt holder.  If you're not going to use the n-fet, wire on/off control to one leg of the fire switch and wire the other leg of the fire switch to ground.

hi mamu thank you for your reply..i have another question,, can i still use zener diode? and i still need 4x 47uF 16v output caps in parallel on vout? im little confuse because in your parts list it says 4x 47uF 16v output caps in parallel (GRM32ER61C476ME15L)..and i dont see those caps on the diagram picture. thanks
« Last Edit: July 24, 2014, 09:54:29 AM by zotek »

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #235 on: July 24, 2014, 03:15:49 PM »
I have a really dumb question. I built my mode and I know what everything is for and how it works except for the N-Fet. Can someone tell me what the N-Fet is for and why I need it? Just trying to educate myself a little in the process.

Thank you.
BFBCAcid

Offline mamu

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #236 on: July 25, 2014, 11:25:51 AM »
hi mamu thank you for your reply..i have another question,, can i still use zener diode? and i still need 4x 47uF 16v output caps in parallel on vout? im little confuse because in your parts list it says 4x 47uF 16v output caps in parallel (GRM32ER61C476ME15L)..and i dont see those caps on the diagram picture. thanks

To use a zener you need the N-FET wiring at on/off control.

I initially used output caps, but the output is stable without them (just not on a breadboard  :laughing:) and for our load purpose they aren't needed so eliminated them.

I have a really dumb question. I built my mode and I know what everything is for and how it works except for the N-Fet. Can someone tell me what the N-Fet is for and why I need it? Just trying to educate myself a little in the process.

Thank you.
BFBCAcid

The N-FET acts like a switch to drive/control on/off (but without the bounce that push button switches sometimes have which can cause problems).  My purpose for using it though is to convert this negative logic module to positive logic via the positive Gate of the N-FET so I can use a zener for low voltage cutoff.
« Last Edit: July 25, 2014, 12:02:26 PM by mamu »

Offline BFBCAcid

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #237 on: July 25, 2014, 12:24:58 PM »
Thanks Mamu,

Now I understand.

Offline BOFH

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #238 on: July 28, 2014, 10:48:19 AM »
Thanks for all the information mamu.

Im trying to finish off a SX350 mod at the moment(need some time to upgrade my printer now the parts have arrived) but once that's done id like to make a real mod.

As Raptors seem to be made from unobtanium at the moment im looking as using this for my first real mod.

So quick question, I noticed the PTR08100W can be pushed over its spec'd 5.5v up to 6v using a slightly lower fixed resistor with the pot.  Is that possible with this chip im guessing about a 1.3k fixed resistor should be about the right value when the pot is zerod for 6V.  Wondering if anyone has tried or is the 5.5v a hard limit? 

Thanks

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #239 on: July 28, 2014, 11:30:11 AM »

So quick question, I noticed the PTR08100W can be pushed over its spec'd 5.5v up to 6v using a slightly lower fixed resistor with the pot.  Is that possible with this chip im guessing about a 1.3k fixed resistor should be about the right value when the pot is zerod for 6V.  Wondering if anyone has tried or is the 5.5v a hard limit? 

Thanks

If you look at the past mods I made w/ the 08100w, you will see that I have an approximate output range of 3.6volts to 6.14volts using a 200 ohm pot w/ a 220 ohm fixed resistor.

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #240 on: July 28, 2014, 11:42:14 AM »
Thanks Breaktru

That was where id got the idea from.  Is it possible to do the same thing with the OKL2-T20 and push it over the 5.5V spec (to around 6v) using a lower resistor and still maintain reliability like you did with the PTR

Thanks

Offline mamu

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #241 on: July 28, 2014, 04:00:33 PM »
The OKL2 is pretty new to all of us so no one knows yet how reliable it is if taking it above spec.   The datasheet says not to exceed max specified output voltage or max power rating, but I don't think a half volt higher than max spec'd would be a big deal as long as you stay within 110W and 20A.  But you do these things at your own risk of course.

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #242 on: July 28, 2014, 05:54:24 PM »
Thanks mamu

Guess I'll have to have a go and see what happens.

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #243 on: July 29, 2014, 07:01:12 PM »
Are the fuses in this circuit necessary?  If so, what do they provide exactly?

According to the product datasheet:

Quote
These converters also include under voltage lock
out (UVLO), output short circuit protection, overcurrent
and over temperature protections.

I don't want to leave them out if they are very important to the safety of the mod but I don't have much space to work with.

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #244 on: July 30, 2014, 08:19:15 AM »
Are there any specific requirements for the Zener or will any do.

Found this one on Mouser http://uk.mouser.com/ProductDetail/Vishay-Semiconductors/1N4734A-TR/?qs=sGAEpiMZZMtQ8nqTKtFS%2fJrR9ou1I1aD%2f58PHwJ%2f8k4%3d will it do the job?

Werkkrew

You never have to have fuses.  But if something goes wrong with your batteries and one goes nuclear or the protection in the circuit fails it could save wrecking everything else.  So they are generally a good idea from a safety perspective as shorted batteries are not fun.  If you are really tight on space maybe you could use two of these http://uk.mouser.com/ProductDetail/Littelfuse/0501010WR/?qs=sGAEpiMZZMtxU2g%2f1juGqVticcWmDLIrN%252bPfJ%2fEGQCw%3d . Downside is if they blow you will have to replace them.

Offline werkkrew

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #245 on: July 30, 2014, 09:22:56 AM »
I'll try to squeeze the re-settable ones I have in there.  Random question, how do these fuses fail, and how do you reset them?  That will help me figure out placement in the box.

http://www.mouser.com/Search/ProductDetail.aspx?R=RGEF1000virtualkey65000000virtualkey650-RGEF1000


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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #246 on: July 30, 2014, 09:48:16 AM »
Explanation of how they work here http://breaktru.com/smf/index.php/topic,691.msg5429.html#msg5429

They reset themselves, you don't have to so can go anywhere in the mod.

Offline CraigHB

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #247 on: July 30, 2014, 01:33:33 PM »
Random question, how do these fuses fail

PTC fuses do not have infinite lifetime.  As the number of trip occurrences goes up, normal resistance also goes up.  At some point the fuse will stay permanently tripped.  Physically bigger fuses last a lot longer and can tolerate thousands of trips without any change in normal resistance.  The really small SMD ones can wear out after a small number of trips, as low as 50.  The SMD ones in a 1206 package or larger are good for a few thousand.  The big leaded ones are good for a lot more. 

Wikipedia has a short article that explains the mechanics of a PTC fuse; http://en.wikipedia.org/wiki/Resettable_fuse

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #248 on: August 04, 2014, 09:37:48 AM »
Hey all my first post on the forum.  I have built about 15 boxes using the okl2 chip and love it! I am curious on what other dc to dc converters are out there that could be used in our hobby.

Offline ModManCooper

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Re: Tinkering with the OKL2-T20 20A 110W dc/dc converter...
« Reply #249 on: August 04, 2014, 09:39:54 AM »
Minus the obvious like Naos Raptors and the okrs  ;cheers;

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