Breaktru Forum

eCigarette Forum => Modding => Topic started by: Breaktru on January 09, 2011, 01:03:23 PM

Title: Digial Potentiometer for Regulator Circuit
Post by: Breaktru on January 09, 2011, 01:03:23 PM
Instead of using an analog variable resistor for selecting your favorite voltage, a digital one would be much nicer.

I have used the SOIC or 8-DIP package. You can solder the SOIC to a break out board. Using the uMax package size is like tying shoe laces on a mosquito so I suggest avoiding those Digital Pot sizes. If you can find it in a 8-Dip package, it will be easier to work with.
The DS1809 and the 1869 are fun to play with and work well. The 04050c booster regulator requires a 100k D.P. and the 08100w regulator will have to be a 10k D.P. with a little circuit mod to get the pot to 200 ohms. See: http://breaktru.com/smf/index.php/topic,244.msg1932.html#msg1932

(http://breaktru.com/temp/PTN04050C.jpg)

(http://breaktru.com/smf/index.php?action=dlattach;topic=244.0;attach=377;image)

(http://breaktru.com/temp/dig_pot1.gif)

How do you adjust the voltage?
It's easy, I used one button for UP and Down instead on 2 separate ones. While holding the FIRE button, The first push decrements the voltage, each push goes to the next lower step. There are 64 resistive steps (taps). When you keep tapping the button it will go all the way to the lowest voltage. Once it bottoms it then starts to increment and visa versa, each tap is a step. If you hold the button it will keep scaling up or down depending on the way it was headed. To change direction, continue to hold the FIRE button and wait a second or two, then hit the UP/DOWN button. After you're at your voltage of choice, let go of the UP/DOWN button while continuing holding the fire button for 1-2 seconds and the setting will be stored in the D.P. chip.
Sounds confusing but after doing it a couple of times, it's quite easy. I placed the two buttons at 90 degrees from each other so it's easy to do it with one hand.
Although I read the spec/instructions several times, I figured it out by trial and error.

One more thing, you know those Digital Meters (1s6s), It wrecks havoc on the operation of varying the voltage. At first I thought I had a problem with my circuit or chips but I switched to my digital multimeter and it worked as designed.
What was happening is, when I went down to 3.24v, I was stuck there and the meter would flash dim to bright and sometimes each flash was a totally different voltage reading. Like I said, It was the D.M. module and not the circuitry. All is now fine and I am truly enjoying my new toy.

**I am happy to share info with all that drop by this forum. So dropping a mention when you post your mod elsewhere would be a decent gesture.
Show your support by signing up as a member and please participate by posting**
Title: Re: Digial Potentiometer for a 5v Regulator
Post by: Breaktru on March 06, 2011, 06:15:10 PM
See post on Variable Volt Booster Regulator where I incorporated the D.P. in a 4050 booster regulator housed in a Copper Mod
at: http://breaktru.com/smf/index.php/topic,177.0.html (http://breaktru.com/smf/index.php/topic,177.0.html)
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: steamEngine on March 29, 2011, 07:10:23 PM
I read your post about those small digital meters (1S-6S) like the one that madvapes and others sell cause problems with the D.P. I'd love to find a digital meter about a quarter of the size. I also read on ECF that your and others are looking for one too. If you find one, please post it. I will do the same.
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: Pantera on June 28, 2011, 05:37:59 PM
I found a few copy cats in the mod world starting to add breaktru's digital pot design.
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: asnider123 on June 29, 2011, 11:27:17 PM
You know those $3 multitesters (you know the ones, with the LCD readouts) .. I wonder if the control circuit is small enough to fit in a boxmod ??? Jes thinkin outloud
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: Breaktru on June 30, 2011, 06:18:20 AM
Probably would. Hell... i'd love to stick one in a tube mod
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: Pantera on July 14, 2011, 10:15:53 AM
I see you added more info to your OP, thanks breaktru
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: Breaktru on August 06, 2011, 08:00:42 AM
See Link for Digital Pot note:
http://breaktru.com/smf/index.php/topic,177.msg1115.html#msg1115 (http://breaktru.com/smf/index.php/topic,177.msg1115.html#msg1115)
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: rookbartley989 on August 07, 2012, 02:34:53 AM
Hey Breaktru, Rook from ECF...I just got a DS1809Z - 100+, it is the 100ohm DP. I just realized this only accepts up to 5v and I was going to try to build it into my 8100. Any thoughts on this, I am using two IMR 14500's to power the 8100.

Thanks,

Ron -
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: Breaktru on August 07, 2012, 08:48:29 AM
Hey Breaktru, Rook from ECF...I just got a DS1809Z - 100+, it is the 100ohm DP. I just realized this only accepts up to 5v and I was going to try to build it into my 8100. Any thoughts on this, I am using two IMR 14500's to power the 8100.

Thanks,
Ron -

Ron, not only is it 5v max, it is a 100K pot and not 100 ohm. You need a 200 ohm pot. The lowest D.P. is 10K
See: Digital Potentiometer for 08100w (http://breaktru.com/smf/index.php/topic,244.msg1932.html#msg1932)
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: synchro on August 11, 2012, 12:19:41 AM
Nice work, very useful design here.

So BT, are we ready to interface a digital pot with an MCU over SPI?  Been looking at components, seems pretty possible but interferes with the display.  Need to take a good hard look at this over the weekend.

Title: Re: Digial Potentiometer for Regulator Circuit
Post by: partstar on June 10, 2014, 05:49:13 PM
 anyone have any experience with this chip? PDT012A0X43-SRZ There is an analog and a digital version. From what i gather from the data sheet it seems like it is designed to work with a digital pot and it is a 12amp chip. The only thing is that it is a SMT chip which would make life a bit more complicated, but if it would work well i would be willing to etch a PCB for it and reflow it.  Been lurking on this forum for a bit and decided to make my first post after i came across this. Any of your opinions would be appreciated.
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: CraigHB on June 10, 2014, 08:12:59 PM
The only way to mount that one is using reflow, which is do-able, but you have to have a host board for it.  Forget about trying to solder wires to that.  Anyway looks like a good part if you wanted to use it.  GE sure publishes thorough data sheets.  I didn't actually read the whole thing but I glanced through it.  That sucker is 40 pages long.
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: partstar on June 11, 2014, 03:38:41 PM
Thanks for checking it out Craig, it's funny that data sheet was probably the first one i read that made the slightest bit of sense to me. Well for the most part anyway. I'm going to give it a shot in the near future, gotta practice on the reflow oven before i make the attempt. I will post my success/failure when i get there.
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: CraigHB on June 11, 2014, 09:25:47 PM
It's not particulary hard to do your own reflow, actually it's easier than hand soldering small components (which I do).  I've done a little bit of reflow and I usually do it in a frying pan.  I find it easier to control the heat in a frying pan than a toaster oven, but it doesn't matter really.  You can use anything you want to heat things up.  Heat guns can do the job too.
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: Jasen on June 11, 2014, 09:30:38 PM
Reflow, I've seen this mentioned here and there. Is it just tossing a copper PCB in the frying pan, put your SMD component's in position and once everything is heated up poke it with your solder?
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: partstar on June 12, 2014, 09:43:06 AM
I am more worried about positioning on the host board, considering how the pads on the chip are laid out and how small they are. Ive done other SMD components like leds and switches and stuff but nothing where i couldn't see the joint when it was done. This seems like a blind joint and that kind of makes me nervous. Not that i haven't had good results with reflow so far, just that i wouldn't be able to inspect it. I usually use a hotplate for reflow but i am building a controller for a toaster oven at the moment.
I would love to get something as tight as your Powerblok boards eventually, but for now i am doing one off break out boards, hand drawn and etched for that artisan feel  ;)
BTW Jasen you are pretty much correct except that you use a solder/flux paste to mount the components and heat the entire board
http://en.wikipedia.org/wiki/Reflow_soldering
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: CraigHB on June 12, 2014, 02:38:04 PM
If you get your PCBs fabbed, you can use the silkscreen layer to provide an outline to line up parts.  You can do the same thing with a home made PCB using a Sharpie and a micrometer, not as easy as ordering out for them of course.  I do blind parts sometimes and that's how I get them lined up.  One thing with reflow is the the surface tension of the melted solder on the pads has a tendency to line things up so even if it's off a bit, it will self adjust an amount when the solder melts.

@Jasen, it's not as simple as frying eggs, but yea, that's about the extent of it.  Though you do have to be careful not to overheat the parts.  They have a limited tolerance for heat and if you use a lot more heat than you need, you can damage the parts. 

You lay a paste on the copper pads, then you drop your parts on the pads, and heat the board up.  The paste is solder in very tiny beads with a liquid flux base.  You can actually get different sizes for the beads in the paste, but it's not a critical thing.  Just about any solder paste that is 63/37 tin/lead with a quality rosin flux will work well. 
Title: Re: Digial Potentiometer for Regulator Circuit
Post by: Jasen on June 12, 2014, 11:42:49 PM
 :)