Author Topic: digital potentiometer (Read 16018 times)

jester · « **on:** June 11, 2012, 07:12:17 AM »

i am looking for a good dig pot what is a good one to work with i like the ds1869+10 but it will not work so good with the 1s-6s meters is there one that will work with the meters or will i have sacrifice the meter or just use to the meter when it is set just for checking i love this moding and you guys cheers jester

Breaktru · « **Reply #1 on:** June 11, 2012, 04:16:17 PM »

If you read carefully (I underlined it) you can use the DS1869 w/ the Dig Meter. This is a quote from my Topic: Vari Volt Booster Regulator w/ Digital Pot - Copper Mod at: http://breaktru.com/smf/index.php/topic,177.msg413.html#msg413

Digital Meters (1S-6S) , 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.
If you use the 1S-6S meter, don't go below 3.6volts.

Note: The DS1869 in the 8-PDIP package is now OBSOLETE
The 1869 operates from 3vand 5v supplies (2.7v to 8v), perfect for the PTN04050c boost module. The replacement is DS1809 which operates from 4.5v to 5.5v.
They still sell the DS1869 in an SOIC package. Just not 8-pin DIP
If you are using two series batteries use the SOIC, DS1669 which operates from 4.5v to 8v
The DS1869 can be used for single or series batteries and operates from 2.7v to 8v

Question: what are you using the 10k D.P. for?

jester · « **Reply #2 on:** June 11, 2012, 04:36:32 PM »

nothing i orded it by mistake i am looking in to it better before order again

jester · « **Reply #3 on:** June 11, 2012, 04:52:35 PM »

which would be the best with the okr would it be the ds1669 and is the wireing the same as the ds1869 cheers jester

jester · « **Reply #4 on:** June 11, 2012, 05:00:14 PM »

could the ds1869+10 be used with the okr

jester · « **Reply #5 on:** June 11, 2012, 05:08:45 PM »

just looked at ds1669 at mouser and it said obsolete

Breaktru · « **Reply #6 on:** June 11, 2012, 05:11:31 PM »

You are using two series batteries so an operating range of 4.5v to 8v would be the DS1669. However you need a 200 ohm. The smallest DS1669 is 10k. If you used a fixed resistor in parallel, linearity would be terrible. I did this with my Side x Side mod. It is hard to adjust and the 64 steps of the DP is pretty large.

jester · « **Reply #7 on:** June 11, 2012, 05:13:46 PM »

ok thank you jester

Breaktru · « **Reply #8 on:** June 11, 2012, 05:14:38 PM »

Quote from: jester on June 11, 2012, 05:08:45 PM

just looked at ds1669 at mouser and it said obsolete

Obsolete in 8-pin DIP, I just bought SOIC yesterday at Digikey. Mouser also has them in SOIC

jester · « **Reply #9 on:** June 15, 2012, 12:35:51 PM »

the ds 1869-10 that mouser uk have as a supply voltage of 2.7 too 8 volts

Breaktru · « **Reply #10 on:** June 15, 2012, 03:01:52 PM »

Quote from: jester on June 11, 2012, 05:00:14 PM

could the ds1869+10 be used with the okr

Yes jimmy you are correct. It operates from 3v or 5v supplies and the range is 2.7v to 8v
I miss read the datasheet

jester · « **Reply #11 on:** June 15, 2012, 03:03:39 PM »

i keep reading and leaning fuses are my next step cheers jimmy

scottericsonon · « **Reply #12 on:** February 18, 2014, 01:37:29 PM »

Has anyone yet come up with a replacement pot for the DS1869?

For single 3.7 cell I mean....

I was sort of looking at the DS1804 but I'm not sure if it would work without a controller

Breaktru · « **Reply #13 on:** February 18, 2014, 04:33:28 PM »

Quote from: scottericsonon on February 18, 2014, 01:37:29 PM

Has anyone yet come up with a replacement pot for the DS1869?

For single 3.7 cell I mean....

I was sort of looking at the DS1804 but I'm not sure if it would work without a controller

The AD5220

scottericsonon · « **Reply #14 on:** February 18, 2014, 04:39:22 PM »

Ooooooo that's purty....
Thank you....

Now if only TI would hurry up with my free samples already

CraigHB · « **Reply #15 on:** February 18, 2014, 04:51:30 PM »

A really cool digital pot I've used before is one from Maxim. Its only available in 10K (MAX5483) or 50K (MAX5484) but it's 10 bit meaning it has 1024 taps. It's pin programmable for an up/down interface or serial interface. These pots have a wide operating voltage range 2.7 to 5.25V.

It's possible the MAX5483 could be used in a parallel configuration for a lower resistance. Having only 10 Ohms per step for the 10k version, it may work well.

Of course the package uses a pretty fine pin pitch so you'd have to do some fine solder work on a PCB. Relfow soldering can make this task pretty trivial and OshPark makes small professionally fabricated PCBs really inexpensive. You can reflow solder with just about anything, heat gun, toaster oven, frying pan, whatever gets the board hot enough. Though a hot air soldering station would be a good investment for this if you plan to do it a lot.

Here's a link to the part. That page shows the TQFN package, but it's also available in a TSSOP package which is easier to work with by hand.

Breaktru · « **Reply #16 on:** February 18, 2014, 05:21:36 PM »

I tried to find an exact replacement for the DS 1869 for the boost PTN04050C which requires a 100K pot.
The AD5220 is a pushbutton or controller interface w/ 128 steps and a power supply voltage of 2.7v to 5.5v. The DS1869 has 64 steps. I like using an 8-PDIP chip because it's easier for ME to work with. I have an assortment of DP chips w/ a small foot print but to me it's frustrating to solder.

I found a schematic showing how to use pushbuttons for a microcontroller interface chip.
http://breaktru.com/smf/index.php/topic,215.msg8912.html#msg8912

scottericsonon · « **Reply #17 on:** February 18, 2014, 05:27:42 PM »

Quote from: Breaktru on February 18, 2014, 05:21:36 PM

I like using an 8-PDIP chip because it's easier for ME to work with. I have an assortment of chips w/ a small foot print but to me it's frustrating to solder.

I'm used to point - point wiring.... Tubes... Giant capacitors and 1/4w and up resistors.....

All these circuit board sized components will be " interesting" for me so the bigger the better....

Breaktru · « **Reply #18 on:** February 18, 2014, 05:38:15 PM »

Quote from: scottericsonon on February 18, 2014, 05:27:42 PM

I'm used to point - point wiring.... Tubes... Giant capacitors and 1/4w and up resistors.....

All these circuit board sized components will be " interesting" for me so the bigger the better....

Yeah me too. I'm an ole timer who learned on tubes.

Just make sure you order the right AD5220. If you are using it for the PTN04050C, make sure it's 100K. And look for the 8-PDIP version.

justinadams · « **Reply #19 on:** April 19, 2014, 11:28:34 PM »

this may be an odd question, and i'm only asking because i can't seem to find the answer elsewhere in the forums (btw awesome forum). i'm looking to adding a digital pot to my Naos Raptor mod and was curious if i needed a 10k or 100k version and are would i need any fixed resistors as well.

Breaktru · « **Reply #20 on:** April 20, 2014, 06:41:55 AM »

You would need a 220 ohm fixed resister and a 200 ohm POT. I don't know of any D.P. that size.

justinadams · « **Reply #21 on:** April 20, 2014, 10:15:43 PM »

that was kinda my fear. i've got it setup currently with a standard pot, but i dont like it as such. do you know of any other way to adjust the trim digitally, maybe with a MCU like one of atmega chips.

Breaktru · « **Reply #22 on:** April 20, 2014, 10:31:24 PM »

Even with an MCU, you would still need to use a Digital Pot. Most are 10K and 100K. A few are 1K.
I used a 10K with a parallel resistor but the Linearity was terrible. Very hard to adjust. See: THIS

You can try a 1K D.P. but only 1/5 of the wipe would be useful which would translate to large jumps in increments depending on how many steps the D.P. has.

justinadams · « **Reply #23 on:** April 20, 2014, 10:34:02 PM »

hmmmm. alright. maybe i can make that work somehow. Thanks for the suggestions.