Help me source a barrel plug, made in Australia ! - Page 1
Forum section: electronics / projects

author: alpher
author_rank: Frequent Contributor
timestamp: September 06, 2018, 12:07:24 am
content: I have this CPAP machine made by RESMED in Australia, been using it for a couple of years now.Works great, now I bought a camper van and since I'm used to it already I want to take it with me on the road, obviously. I know that there are a special car adapters available on eBay and such, but I'll be damned if I pay $180 for a simple 12 to 24V converter. My problem is that try as I might I cannot find the exact barrel plug that powers the machine, I've tried mouser, newark, digikey and allied, no luck there.I attached a couple of pics of the plug, the dimensions are: OD= 7.5mm, ID= 5mm and there is a central pin in the middle of about 1mm diameter, don't know if it matters, maybe for a shelding ?

author: amyk
author_rank: Super Contributor
timestamp: September 06, 2018, 01:59:16 am
content: Are you sure it's not 7.4x 5mm? That's a common size.https://www.aliexpress.com/item/DC-7-4mm-x-5-0mm-Plug-Socket-Connector-with-Cord-1-2M-Cable-for-HP/1925083279.html

author: alpher
author_rank: Frequent Contributor
timestamp: September 06, 2018, 02:13:04 am
content: 7.4mm is certainly feasible, but still ot available from any of the suppliers that I normaly use.I do not usually mind the aliexpress, but is time I'd prefer something reliable.

author: Bratster
author_rank: Frequent Contributor
timestamp: September 06, 2018, 05:02:16 am
content: That looks like the older style Dell and HP laptop power supply connectors.I don't have one in front of me to check dimensions.Sent from my Fi Moto x4 using Tapatalk

author: Hydron
author_rank: Super Contributor
timestamp: September 06, 2018, 08:54:10 am
content: Can confirm a match with a HP laptop power plug (and Dell, I know that they're physically compatible, though machines refuse to charge when the wrong brand adapter is used). OD is 7.4, ID 5.0mm.RE the centre pin, on the Dell adapters (and I suspect HP as well) it is connected to a maxim one-wire EEPROM type chip to supply an ID and charger capability info to the laptop (and at the same time making it harder to replace the adapter with a generic or DIY equivalent, making Dell/HP more money supplying replacements...). The one-wire chip has a habit of dying (who would have guessed having a ~5V max tolerant pin right next to 19.5V could occasionally end in tears!), going back to my previous comment about Dell/HP making money, not even counting the enormous waste of having to discard a perfectly functional PSU becasue an ID chip fails...If your original PSU also has a similar ID system then you can probably find out (multimeter in ohms mode between outer shell and centre pin will probably show a moderate to high resistance (but not open circuit) if there is something similar present. If so you may need to see if you can copy the info onto a new chip for your DIY adapter - there will certainly be info on the web about doing this for the laptop chargers. If you're lucky it might turn out to be a simple resistor ID or simply un-used.

author: station240
author_rank: Unknown
timestamp: September 06, 2018, 11:34:51 am
content: I've got one of those plugs fitted to a Lenovo laptop PSU65W 20VFPU P/N: 92P1153

author: DTJ
author_rank: Super Contributor
timestamp: September 06, 2018, 11:59:54 am
content: Maybe check out your nearest used PC/Laptop shop and they might give you one from an old laptop SMPS out of the scraps box.

author: Leeima
author_rank: Contributor
timestamp: June 23, 2022, 12:50:43 pm
content: I know this is a long dead topic, but I recently had two of my chargers fail in exactly the same way.And I'll probably have to come back to this thread in future when another one fails.I found this connector mates perfectly well (OD=7.4mm ID=5.1mm CentrePin=0.6mm) and it's a solder wire mount so it's really easy to fitCUI Devices PP-065574-M (https://www.cuidevices.com/product/resource/pp-065574-m.pdf)