Advice sought on in-line 2-wire plug/socket pair - Page 1
Forum section: electronics / repair

author: max.wwwang
author_rank: Frequent Contributor
timestamp: February 02, 2024, 05:20:46 am
content: In repairing one sewing machine, which had a broken motor speed controller for which there was nowhere I could find working replacement parts, I managed to adapt a modern controller for it and got it back to work perfectly. Now I find myself in need of applying the same trick for another aged controller, and I don't want to source, and stock, another duplicate controller. Rather, I'd like to use the same one, interchangeable for both machines. To achieve this, I'm looking for a decent in-line 2-wire plug/socket pair that's intended for mains voltage and with a rating of, preferably, 0.5-1A or so, and is designed for repeated plugging and unplugging without compromising the performance or safety. Because of its being in the middle of a wire (in-line, just like the switch of some bed-side lamps), I would like it to be compact, light-weight, among other good features.Obviously, there are loads of products out there, and many are cheap, such asthis. I would however like to hear any suggestions you guys might have.Thanks.

author: abeyer
author_rank: Frequent Contributor
timestamp: February 02, 2024, 06:47:42 am
content: What about IEC C7/8? The inline sockets aren't terribly common, but they exist, and I've seen reasonable quality ones before.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: February 02, 2024, 07:17:12 am
content: Quote from: abeyer on February 02, 2024, 06:47:42 amThank you. That should be good enough. The problem though, is that I've not seen such products that can be re-wired, or with the socket side that can be used in-line.

author: Ian.M
author_rank: Super Contributor
timestamp: February 02, 2024, 07:42:41 am
content: Older sewing machines commonly used universal motors with a series rheostat for speed control. Beware of using any mains connector in common domestic use in your country for the controller to universal motor connection!A modern controller is probably electronic, and many output DC, either from a SCR controlled bridge doing phase angle speed control, or bridge + MOSFET PWM speed control. If an ordinary mains powered device is connected to it by a user that doesn't know better bad things are likely to happen, resulting in device or speed controller burnout, or both.TLDR: Use an uncommon mains rated connector!

author: max.wwwang
author_rank: Frequent Contributor
timestamp: February 02, 2024, 09:24:53 am
content: Quote from: Ian.M on February 02, 2024, 07:42:41 amI don't quite get that. Can you explain a bit more. Thanks.Quote from: Ian.M on February 02, 2024, 07:42:41 amI fully understand what I'm doing, what the old controller was doing as well as what the new one is now. Very true, both of the machines use universal motors. The old controller uses brute force power resistor in series whereas the modern one uses TRIAC electronics and is generally better.

author: Ian.M
author_rank: Super Contributor
timestamp: February 02, 2024, 09:38:15 am
content: If there is any risk of anyone other than yourself using it, then don't use a connector that is in common use in your country for mains devices, between the speed controller and the motor. i.e. *DONT* use IEC C7/C8

author: max.wwwang
author_rank: Frequent Contributor
timestamp: February 02, 2024, 09:43:13 am
content: Quote from: Ian.M on February 02, 2024, 09:38:15 amThanks for your elaboration. Much appreciated.First, this is only for my use not anyone else, at least not anyone else outside my household. Anyone using it will have to be instructed of its safe use, though of course I strive to make it fool-proof.Second, can you explain why I should not use IEC C7/C8? They are commonly seen even on modern sewing machines, which without exception are class II appliances. Sorry I'm a bit slow here.

author: Ian.M
author_rank: Super Contributor
timestamp: February 02, 2024, 10:07:14 am
content: IEC C7/C8 is *far* too common and the general public have the expectation that all IEC C7 leads are interchangeable.The risk is if something other than a universal motor is plugged into the speed controller. You obviously wont do that, and you can probably prevent your family doing so, but from "... and I don't want to source, andstock, another duplicate controller." in your initial post, until your last reply I thought there was a risk you were doing these controller replacements for friends or customers, so were unable to control end-user stupidity.Have you seen any machine that uses IEC C7/C8 for the foot pedal, other than as power in straight from the wall?

author: max.wwwang
author_rank: Frequent Contributor
timestamp: February 02, 2024, 08:06:30 pm
content: Quote from: Ian.M on February 02, 2024, 10:07:14 amI see! Thank you. Even not for customers or friends, it’s a good and valid point.

author: jdragoset
author_rank: Frequent Contributor
timestamp: February 02, 2024, 09:30:30 pm
content: https://www.belfuse.com/product-detail/industrial-cinch-300-series

author: themadhippy
author_rank: Super Contributor
timestamp: February 02, 2024, 09:37:21 pm
content: If its something different your after hows about the neutrik true1https://www.neutrik.com/en/neutrik/products/powercon/powercon-true1-top/powercon-true1-top-cable-connectors

author: max.wwwang
author_rank: Frequent Contributor
timestamp: February 04, 2024, 10:38:31 pm
content: Quote from: themadhippy on February 02, 2024, 09:37:21 pmCertainly, these are very decent products, though the two big ones are for big cables (my case is small cable), and the other two are rated for 16A or 20A, which are far too much an overkill. Plus the price would be too dear for my humble use case. But thank you!

author: max.wwwang
author_rank: Frequent Contributor
timestamp: February 04, 2024, 10:46:11 pm
content: Quote from: themadhippy on February 02, 2024, 09:37:21 pmThis is very interesting. The types on pages 11 and 12 are very close to what I'm after (Pin number=2). Thanks.The again, the price is too dear. Apparently, I would need two pieces so it would be NZ$70 or so!https://www.digikey.co.nz/en/products/detail/cinch-connectivity-solutions/P-302H-CCT/1278729?utm_adgroup=&utm_source=google&utm_medium=cpc&utm_campaign=Pmax%20Shopping_Low%20Performing%20Products&utm_term=&productid=1278729&utm_content=&utm_id=go_cmp-20114171714_adg-_ad-__dev-c_ext-_prd-1278729_sig-CjwKCAiAiP2tBhBXEiwACslfnujyNyh2Rd59j6vFZoyuW7tnFqfgAg-tfKgAdfHM_yxbInc4jKnVYBoCWscQAvD_BwE&gad_source=1&gclid=CjwKCAiAiP2tBhBXEiwACslfnujyNyh2Rd59j6vFZoyuW7tnFqfgAg-tfKgAdfHM_yxbInc4jKnVYBoCWscQAvD_BwE Actually I would obviously need 3, or more. So it’s at least NZD 105 or so. That’s too much.