Is there an easier way to solder these? - Page 1
Forum section: electronics / beginners

author: ecowarrior
author_rank: Contributor
timestamp: March 09, 2011, 09:11:22 pm
content: Trying to solder wires onto the little tabs that are at the bottom of a potentiometer. The POT I have is an Alps RK097 but a lot of these seem similar. I'm wondering how you are supposed to solder wires to the little tabs at the bottom. Perhaps you just aren't supposed to? Perhaps the are designed to be soldered to a PCB maybe. Not sure, but plenty of people DO seem to be soldering wires to them for the particular build I'm trying to do (headphone amp).The tabs don't have any holes in them, they are simply small little tabs of metal - you can just about see them in this pic:I am managing to do it - just, but it's fiddly, the connection doesn't seem *that* strong, and I'm wondering if there is something I'm missing here - perhaps some little connector I'm supposed to be using.Any ideas?

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 09, 2011, 10:05:34 pm
content: Wrap the wires around the pins, then solder them.

author: Bored@Work
author_rank: Super Contributor
timestamp: March 09, 2011, 10:07:42 pm
content: They are supposed to be mounted on a PCB (through-hole).

author: Simon
author_rank: Unknown
timestamp: March 09, 2011, 10:09:32 pm
content: Quote from: BoredAtWork on March 09, 2011, 10:07:42 pmWas just about to type the same, you might be able to make a small pcb just to sit the pot on and take wires from if you want to mount it on a case and no close to the main PCB

author: Zero999
author_rank: Super Contributor
timestamp: March 09, 2011, 11:05:09 pm
content: It might fit on a stripboard, what's the distance between the pins and are they arranged in a grid pattern?

author: Psi
author_rank: Super Contributor
timestamp: March 09, 2011, 11:35:04 pm
content: From the look of those they are very old. The pin surface has probably aged and doesn't want to accept solder.Get a small file and give each pin a file on all 4 sides. If that's the problem it should make a huge difference and soldering them should become easy. (use the file so the metal filings fall away from the pot and not inside it)You could try instead to add flux on the pins before soldering but you want to avoid getting flux inside the pot as it will destroy the pot internals.The pot might have a large amount of internal metal connected to each of the pins, you may have to hold the iron on a pin for quite a while before the whole thing heats up enough to accept solder.The solder should melt when you touch it onto the pin. If it only melts when you touch it onto the iron tip (which is touching the pin), then the pin isnt hot enough.

author: the_raptor
author_rank: Regular Contributor
timestamp: March 10, 2011, 04:29:01 am
content: Apart from what Psi said doing this kind of work is a lot easier if you tin the pin and wire first and then bring them together for the final join.Remember that if the solder joint is a good one that you shouldn't be able to pull it apart with your hands, they should be pretty strong.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 10, 2011, 04:55:59 am
content: 1) it suppose to be on pcb2) a (third) helping hand will be much helpfull for non pcb soldering3) dont solder too long as high temp reaching the inside pot element (carbon?) that can damage them

author: ecowarrior
author_rank: Contributor
timestamp: March 10, 2011, 07:29:36 am
content: Thanks guys - I think you're confirming my own thoughts. Might try it on a bit of stripboard and see how I go.Cheers.

author: Psi
author_rank: Super Contributor
timestamp: March 10, 2011, 08:49:15 am
content: you should be able to solder wire directly onto those pins without the need for stripboard, but if it makes things easier then why not.

author: Unknown
author_rank: Unknown
timestamp: March 10, 2011, 12:43:29 pm
content: I have used the same pot.If you want to use a matrix board AND the pins are too thick AND you dont want to trim them, you could bring the edge of the matrix board up to them and bend them on it and solder them, then wires ans ome hot glue for the board.If you decide to directly wire them, do the wiring once the pot is installed in the enclosure which should give you the opportunity to minimise the stress on the pins.As a general rule for pins, it is not the stress that breaks them as it is metal fatigue from repetitive bending back and forth.Hope this helps.

author: ecowarrior
author_rank: Contributor
timestamp: March 11, 2011, 11:43:51 am
content: Thanks all.Actually what I've decided to do is learn how to make up my own PCBs and go down that route instead. I like a challenge but blimey it's not as easy as I thought it would be

author: orbiter
author_rank: Frequent Contributor
timestamp: March 11, 2011, 01:08:45 pm
content: You could also perhaps try a few of these tiny slip-on connectors, then solder them to the pins.The pins below are 0.6mm

author: Zad
author_rank: Super Contributor
timestamp: March 11, 2011, 05:52:29 pm
content: Quote from: ecowarrior on March 11, 2011, 11:43:51 amIt is for something like this. You don't need to use CAD or even photo-etch. Just get a small piece of copper clad and a resist pen. Mark where the pins are, and where you want the connector to be. Draw lines between the two. Etch. Wash. Drill.You can do it the pretty way if you want, but electrons rarely care how pretty your PCB is.

author: ecowarrior
author_rank: Contributor
timestamp: March 11, 2011, 09:22:31 pm
content: Oh you have NO idea how bad my OCD and perfectionism can getGood advice though, ta. Never etched a PCB before. Just trying to get to grips with everything that's required but what I'd really like to do is get the pot onto the same PCB as the bulk of components, so I'm trying to figure out FreePCB and the joys of nets, part codes, and mil-mm conversion right now.I may choose to go off my head in a bit, see if that helps

author: sonicj
author_rank: Frequent Contributor
timestamp: March 12, 2011, 06:06:45 am
content: Quote from: ecowarrior on March 11, 2011, 09:22:31 pmNASA takes OCD to a whole 'notha levelworkmanship.nasa.gov - through hole terminalsafter you're done with that, check outNASA-STD-8739.1on how to stake the wires. then you can head over toNASA-STD-8739.4for wire management and harness forming.-sj

author: sonicj
author_rank: Frequent Contributor
timestamp: March 12, 2011, 06:14:43 am
content: btw, did you order those from the US?i've had a helluva time finding dual logarithmic pots like that. i ended up using a panasonic pot that im not too happy with.-sj

author: Unknown
author_rank: Unknown
timestamp: March 12, 2011, 11:17:25 am
content: http://www.hificollective.co.uk/

author: ecowarrior
author_rank: Contributor
timestamp: March 12, 2011, 05:23:07 pm
content: Nice, didn't know about that site.I have bought a few things from here:www.chelmer-audio.combut the Alps RK097 I got from ebay and it came from Latvia of all places!Little audio circuits are my 'thing' at the moment and having got really nice results from a relatively basic "chu moy" headphone amp I think I'm going to build it again using higher-grade components - whether it will make much difference don't know, but partly it will challenge me to build it carefully (and now on a PCB too if I can figure that out!).

author: sonicj
author_rank: Frequent Contributor
timestamp: March 13, 2011, 07:58:04 am
content: lol! thats what i was building when i was looking for pots!mine sounded great! i partially rebuilt it and lost focus so its sitting on the corner of the desk.-sj

author: ecowarrior
author_rank: Contributor
timestamp: March 13, 2011, 08:37:44 am
content: Yep I wanted to build one for ages and it was that which got me re-started in Electronics. Built my first one a couple of months back, not into a tin but into a smallish plastic enclosure, and it sits on my desk here plugged into the Mac, and does wonders for my Sennheiser HD555's.Built another, but DID try to get this one into a tin - the IC almost caught fire :O) Waiting for a replacement IC and new caps.Now I'm finding myself wanting to build it for a third and final (?) time with upgraded and larger caps, better components generally, and I'm well on the way now to getting my PCB layout done. Chances are after all this it won't sound any better than my first attempt but what the hell, it's all about fun, achievement, and a lot of OCD

author: Zero999
author_rank: Super Contributor
timestamp: March 13, 2011, 11:48:46 am
content: Lol I can't believe those sites claim shitty carbon resistors are good for audio.http://www.hificollective.co.uk/www.chelmer-audio.comCarbon composition resistors are terrible. They're very noisy, exhibit poor tolerance, long term stability and high temperature coefficient. The only good thing about them is they can withstand higher energy pulses than carbon/metal film. You should use metal film or wire wound for all resistors which pass audio. Carbon film/composition resistors should never be used for audio. Carbon film are very cheap so handy if you need them for series resistors for LEDs. Carbon composition resistors really have no place in modern electronics so you can replace them with alternatives. As mentioned before, they do have a higher surge capacity so you might want to replace them with resistors with a higher power rating, if that's important.

author: Unknown
author_rank: Unknown
timestamp: March 13, 2011, 12:18:47 pm
content: Quote from: Hero999 on March 13, 2011, 11:48:46 amThey also have a parasitic lower inductance than carbon/metal film resistors, since the resistive element is solid instead of a serpent shape. 1/4-1/2W film resistors have in the order of 10nH of parasitic inductance. This is obviously completely insignificant for audio (which is essentially DC as far as parasitics are concerned), but can be quite significant at high (GHz) frequencies.

author: Zero999
author_rank: Super Contributor
timestamp: March 13, 2011, 12:51:45 pm
content: Quote from: alm on March 13, 2011, 12:18:47 pmIf that's a problem then you should use thin film resistors, not crappy carbon composition.Obviously don't use wire wound for RF for the same reason.