instead of 20K potentiometer 2 x 10K potentiometers - Page 1
Forum section: electronics / beginners

author: Savetheday
author_rank: Regular Contributor
timestamp: August 26, 2017, 11:37:10 pm
content: HiI would like to know how to use instead of one 20k potentiometer, 2 x 10K ohm potentiometers.How should we hook up 3 pins?A 10K B 10Kl l l l l lA1 A2 A3 B1 B2 B3A2 connected B1andA1 B2 B3Does it work like that?thanks.

author: wraper
author_rank: Unknown
timestamp: August 26, 2017, 11:57:45 pm
content: Depends on what you want to get as a result. If you want to regulate total resistance in 0-20k range or if it works like voltage divider (like sound volume regulator) are two completely different cases.

author: Savetheday
author_rank: Regular Contributor
timestamp: August 27, 2017, 12:02:42 am
content: Quote from: wraper on August 26, 2017, 11:57:45 pmI need to use one 20K potentiometer but right now I don't have it.So I thought I could use two 10K.

author: wraper
author_rank: Unknown
timestamp: August 27, 2017, 12:06:14 am
content: You did not answer the question of what you want to achieve. In many cases you could just use one 10k Resistor. In other cases you might add 10k fixed resistor in deries.

author: Savetheday
author_rank: Regular Contributor
timestamp: August 27, 2017, 12:11:25 am
content: Quote from: wraper on August 27, 2017, 12:06:14 amOk I need to go 1 ohm up to 20k ohms.

author: wraper
author_rank: Unknown
timestamp: August 27, 2017, 12:18:32 am
content: 1 ohm? If you said 0-20k, it would appear fine. But 1 Ohm implies you want to achieve at least remotely precise resistance at such low range which is not real with 20k of total resistance.

author: ludzinc
author_rank: Unknown
timestamp: August 27, 2017, 01:48:35 am
content: Quote from: wraper on August 27, 2017, 12:18:32 amGive the newbie a break and stop tormenting the guy.

author: wraper
author_rank: Unknown
timestamp: August 27, 2017, 08:34:34 am
content: Quote from: ludzinc on August 27, 2017, 01:48:35 amWho is tormenting anyone? I rather try him to avoid wasting time and tormenting himself by doing thing inadequate for particular purpose.

author: sasa
author_rank: Regular Contributor
timestamp: August 27, 2017, 09:32:23 am
content: Quote from: Savetheday on August 26, 2017, 11:37:10 pmTwo pins are enough (one of border and middle one), if that is simpler for you. Or you can do as already suggest. Only take care on which direction you want to rotate knob to manage resistance - then use appropriate pins. If minimum resistance of 1 ohm is necessary, ensure one in series (or cheaper make one 10x 10 Ohm in parallel),When I made constant load circuit, it certainly I did not wanted expensive multiple turns pot in order to calibrate current precisely. Instead, I used several different values pots, similar you required.It actually depends what precision you need. If not critical, 2x 10k pot in either connectivity (use 2 or 3 pins) is sufficient.If you want to use 2x 10K pots instead 1x 20K as voltage divider, that is a bit more complex indeed and you have to specify a bit desired ratios.

author: wraper
author_rank: Unknown
timestamp: August 27, 2017, 03:34:38 pm
content: Quote from: sasa on August 27, 2017, 09:32:23 amThe issue with connecting only 2 pins is that if potentiometer is crappy or wears out, when adjusting it, connection may get lost for a brief moment and it becomes open. In some applications (like PSU) it may case grieve consequences (like high voltage spike somewhere in the cirquit). Therefore it's better to connect middle pin to one of the side pins, so maximum possible resistance is limited even if slider connection is lost.

author: sasa
author_rank: Regular Contributor
timestamp: August 27, 2017, 03:48:03 pm
content: Quote from: wraper on August 27, 2017, 03:34:38 pmIndeed. And because of that it is always better to give a hint what is doing and with what. I have never had a problem with metal pots on breadboard during initial tests hooking it in 2 wire configuration, however with plastic pots or even stocking trim-pots that is quite often bad decision.I supposed this is just temp solution while acquire exact value pot for permanent use.

author: Brumby
author_rank: Unknown
timestamp: August 28, 2017, 01:56:09 am
content: Quote from: wraper on August 27, 2017, 12:18:32 amNot necessarily. The OP may just need to ensure there is never a dead short.But this is just more speculation ... having a bit more of an idea of what this 20K will be doing could make for a more focussed discussion.

author: Zero999
author_rank: Super Contributor
timestamp: August 28, 2017, 08:16:57 am
content: Quote from: Savetheday on August 27, 2017, 12:11:25 amDo you mean, you need a minimum resistance of 1Ohm or you want the resistance to be able to go down to 1Ohm or under?If you need a minimum resistance of 1Ohm, then adding a series resistor will do.If you need a minimum resistance of 1Ohm or below, then that's more tricky, as the wiper's contact resistance may be higher than that.