I would rather buy 1% resistors from the get go. Plus I have money in my paypal account I need to burn, lol.
Easy OKR-T VV mod
- Thread starter bstedh
- Start date
- th_trl_thread_readers 0
- Status
Somebody found a new toy for the OKR mods.
I think it was posted in one of Asnider's threads. If I remember correctly it was the energizer bunny one. Less than 1/2" square....
Digi-Key - 811-2214-1-ND (Manufacturer - OKL-T/6-W12N-C)
I think it was posted in one of Asnider's threads. If I remember correctly it was the energizer bunny one. Less than 1/2" square....
Digi-Key - 811-2214-1-ND (Manufacturer - OKL-T/6-W12N-C)
I have a couple of those on the way already, lol. The top end is 5.5 instead of 6V thogh.
Last edited:
ok got a question I have been wondering. would you have to use a 200 ohm pot or if i had a 10k or a 100k pot on hand, which I do, is there a way I could use them and keep the regulator in range? if so how would one figure that out, is there an equation that is used. I may have over looked this in my reading on variable chips, and would like to know, it would help with the variety of pots one could use.
Equation for control pin voltage is on the spec sheet.
You need another pot for the OKR
You need another pot for the OKR
Equation for control pin voltage is on the spec sheet.
You need another pot for the OKR
thank you for the quick response. i figured i couldn't use them but worth a shot, and now i can figure it out myself. thank you once agian
No problem.
It's gets a little confusing with the different types of boost circuits. Some take high resistance some take lower resistance.
The usable range with the OKR can be had with a total resistance from about 220 ohms to 440 ohms.
Some folks use 220 ohms fixed plus a 200 ohm pot for a total range of 220 to 420 ohms.
I use 300 ohms and a 100 ohm pot for a range of 300 to 400. Doesn't go as high in volts but gives a finer adjustment.
If you are going to buy a few 50 cent pots and some 9 cent resistors, go ahead and get an assortment so you can 'Fine Tune' your mod to the range you expect to use.
It's gets a little confusing with the different types of boost circuits. Some take high resistance some take lower resistance.
The usable range with the OKR can be had with a total resistance from about 220 ohms to 440 ohms.
Some folks use 220 ohms fixed plus a 200 ohm pot for a total range of 220 to 420 ohms.
I use 300 ohms and a 100 ohm pot for a range of 300 to 400. Doesn't go as high in volts but gives a finer adjustment.
If you are going to buy a few 50 cent pots and some 9 cent resistors, go ahead and get an assortment so you can 'Fine Tune' your mod to the range you expect to use.
The important thing is to observe the minimum resistance to keep these chips in spec. The OKR wants 220 (for 6V max), the so called Evercool (the TI switching regulators) want 240Ω (for 5.5V max). The datasheets are quite adamant about these values. As far as trimmers CapCad used a 1k with his OKR. It obviously will work fine, but if a single turn trimmer is used a few degrees of the trimmer are lost to the part that corresponds to the under ~3.3V range, making for twitchy adjustments. But going with a 12 - 25 turn trimmer will give you back the granularity needed for fine, precise adjustments.
I notice amongst the hack modders they just leave out the fixed resistor and are just going with maybe a 500Ω trimmer on either reg.
I notice amongst the hack modders they just leave out the fixed resistor and are just going with maybe a 500Ω trimmer on either reg.
I agree Willy,
but it shouldn't be much of a problem to 'think before you buy' and design the fixed/variable resistance to fit your needs rather than follow the Collie.
Not understanding the circuitry, just building to the pictures, doesn't help when it comes time to troubleshoot your failures
but it shouldn't be much of a problem to 'think before you buy' and design the fixed/variable resistance to fit your needs rather than follow the Collie.
Not understanding the circuitry, just building to the pictures, doesn't help when it comes time to troubleshoot your failures
I agree Willy,
but it shouldn't be much of a problem to 'think before you buy' and design the fixed/variable resistance to fit your needs rather than follow the Collie.
Not understanding the circuitry, just building to the pictures, doesn't help when it comes time to troubleshoot your failures
Now you tell me. LOL
Wow. Easy build and works like a champ. I used the page 1 specs with the exception of the switch. 3AA box.
I think I'll make one for 2x18650s next.
Thanks bstdeh!
I think I'll make one for 2x18650s next.
Thanks bstdeh!
I just got a project box to make one 2X18650. I wanted to make it 3X18650 but the box isn't as big as I thought it was. Can't wait, Just need to find the time to sit down and build it. I going to use the on/off pin this time with a tack switch and put a zener in to cut it off as I only have un-protected batteries and they will drain down pretty low with this setup if you let them.
I am still looking for a good knob type POT to use. I may use the OKL version instead to hopefully be able to use a wider variety of POT types. Still researching all the parts I plan on using =]
Nice. I think I'll try an altoids box. Worried a little bit about isolating the components in a metal box. Should be interesting. I better keep it simple and duplicate what I've done only bigger.
I have a couple n00bish questions on this circuit. I think my brain is suffering info overload from reading about this stuff for the last week . . . the more I learn the more I realize I don't know
With a 10k pulldown resistor for using a tac switch, does the switch still go to pin 2 on the regulator?
Also, on the above, where exactly in the circuit would a zener and resistor go for low volt cut-out? I saw the diagram in the thread on that subject (linked back on page 9), but was a little confused by the differences between that and the one in the start of this thread
I don't mind experimenting, but I'd like a better leg to stand on than just my novice assumptions ;-)
With a 10k pulldown resistor for using a tac switch, does the switch still go to pin 2 on the regulator?
Also, on the above, where exactly in the circuit would a zener and resistor go for low volt cut-out? I saw the diagram in the thread on that subject (linked back on page 9), but was a little confused by the differences between that and the one in the start of this thread
I don't mind experimenting, but I'd like a better leg to stand on than just my novice assumptions ;-)
"With a 10k pulldown resistor for using a tac switch, does the switch still go to pin 2 on the regulator?"
The switch goes to pin 1 to activate the regulator. Supply positive voltage through the tac switch which overcomes the pull down resistor allowing it to turn on.
"Also, on the above, where exactly in the circuit would a zener and resistor go for low volt cut-out? I saw the diagram in the thread on that subject (linked back on page 9), but was a little confused by the differences between that and the one in the start of this thread"
The Zener goes in line with the switch. As it will only conduct if the supply voltage is above the zener ratting. This allows you to select a zener at the lowest voltage you want your batteries to run down to. If the batteries drop below this voltage the zener will not conduct which will not allow your switch to activate the circuit. You do still need to worry a little if you will have the mod sitting idle for a couple of weeks as the regulator will draw a small trickle of juice when off.
Also you are supplying main juice to the regulator positive terminal so it may be wise to put a master switch on the battery positive if you have the room in your mod to do so. I just pull the battery if the mod is not going to be in use.
The switch goes to pin 1 to activate the regulator. Supply positive voltage through the tac switch which overcomes the pull down resistor allowing it to turn on.
"Also, on the above, where exactly in the circuit would a zener and resistor go for low volt cut-out? I saw the diagram in the thread on that subject (linked back on page 9), but was a little confused by the differences between that and the one in the start of this thread"
The Zener goes in line with the switch. As it will only conduct if the supply voltage is above the zener ratting. This allows you to select a zener at the lowest voltage you want your batteries to run down to. If the batteries drop below this voltage the zener will not conduct which will not allow your switch to activate the circuit. You do still need to worry a little if you will have the mod sitting idle for a couple of weeks as the regulator will draw a small trickle of juice when off.
Also you are supplying main juice to the regulator positive terminal so it may be wise to put a master switch on the battery positive if you have the room in your mod to do so. I just pull the battery if the mod is not going to be in use.
Cool, thanks. As for the mod "sitting for a couple weeks", I'm .... about not leaving batteries in things that aren't currently being used, so that won't be a problem ;-) The master on/off switch location won't be a problem either since I'll probably choose or design my enclosure based on the footprint of all the innards rather than build to suit a certain enclosure. I haven't even decided what size batts to use, 2x 18650 is probably overkill, I'm thinking maybe 18350's to keep the box smaller. In this case, I don't mind having to swap out batts later in the day
I used the OKR-T10 and have no voltage at the atty connector. I know my circuit is built as shown in the OP with identical parts All connections checked w/ continuity. I'll post a pic of the circuit and tell me what you think. Sorry about the epoxy boogers. I was attaching a 9mm casing to the POT for a knob. When I tapped the neg from board to pos from switch I get 8.4v from hot 18650s. The switch is not pictured, but picked up the battery+ to the red wire on the front of the board. The black and red on the back of the board go to connector. Here's the mess:
Last edited:
Question about selecting the Zener voltage.
The spec defined range for the control pin is zero to 0.4 volts for an OFF condition and Greater than 1.5 volts for an ON condition. If you don't want you cell stack to go below, lets say 6 volts (3volts per cell), a 6 volt Zener from Vin to the control pin and a 10K resistor from there to ground will give what voltage at the control pin?
A control pin voltage between 0.4 volts and 1.5 volts MAY do something. Maybe OFF, maybe ON, sometimes, or NOT.
The spec defined range for the control pin is zero to 0.4 volts for an OFF condition and Greater than 1.5 volts for an ON condition. If you don't want you cell stack to go below, lets say 6 volts (3volts per cell), a 6 volt Zener from Vin to the control pin and a 10K resistor from there to ground will give what voltage at the control pin?
A control pin voltage between 0.4 volts and 1.5 volts MAY do something. Maybe OFF, maybe ON, sometimes, or NOT.
From the testing I've done with zener diodes and this converter, 0.4v plus the zener volts = voltage cutoff. If you want a 6v cutoff, use a 5.6v zener.
I'm not sure about the wiring you mentioned though. I wire the zener to pin1 of the converter, then one terminal of the atty switch to the other end of the zener. If you also want an LED batt status indicator it needs its own zener. The LED lights if the input voltage is above 6v (it gets really dim between 6.5v and 6v) and doesn't light when the input voltage is below 6v.
Sumfin like this:
Last edited:
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
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
- Status
Similar threads
- Locked
