Why aren't all 6V adapters the same?

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Tinshed

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Topic # 231881 18-Mar-2018 15:34

I have a device for measuring blood pressure that can be powered by a AC/DC 6V adapter, inanition to batteries. Since I don't have such an adapter amongst my many adapters, I bought a AC/DC 6V adapter from Trademe. However when the said adapter arrived yesterday the plug doesn't fit my blood pressure device - it is too big. I had naively assumed all 6V adapters would be the same. Clearly they are not. What do I need to ensure that I buy the right 6V adapter from my blood pressure device? (I checked the manual for device and it just refers to an optional "Adapter S").

Tinshed
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PeterReader

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Reply # 1979350 18-Mar-2018 15:34

Hmmmm. Here we go.

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elpenguino

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Reply # 1979356 18-Mar-2018 15:43

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the main pitfalls are:

getting an ac power adapter when your device wants dc

getting the wrong sized plug or centre pin

If there's no information about exactly which pin size it needs, is there an old power adapter to measure?

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andrewNZ

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Reply # 1979366 18-Mar-2018 15:51

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Because manufacturers are dicks.

The simplest solution will be to go to Jaycar and get a universal one.

Otherwise you need to know:
Voltage.
AC or DC .
Current - you need an adapter that gives at least as much as your device is rated for.
Plug size - there are many and some look pretty similar.
Plug polarity - this only matters if the device is DC then it can be very important.

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Tinshed

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Reply # 1979369 18-Mar-2018 15:59

andrewNZ: Because manufacturers are dicks.

The simplest solution will be to go to Jaycar and get a universal one.

Otherwise you need to know:
Voltage.
AC or DC .
Current - you need an adapter that gives at least as much as your device is rated for.
Plug size - there are many and some look pretty similar.
Plug polarity - this only matters if the device is DC then it can be very important.

Thanks, I'll try Jaycars. Bloody nuisance though...

Tinshed
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richms

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Reply # 1979403 18-Mar-2018 17:48

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The reason that they do the different plug sizes is to stop incorrect ones being used from within their own product range, since people will just pick up a sony adapter and try to plug it into a sony appliance etc. Between brands there isnt really a standard. There was supposed to be with the yellow tipped ones but that didnt work out at all with companies doing their own things with the variaty of new sizes that came with the yellow plugs. Now I have seen blue ones on other gear, not sure how they differ from the others as far as size goes, but the whole idea is to stop wrong ones being connected.

Richard rich.ms

gzt

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Reply # 1979434 18-Mar-2018 18:53

Take the blood pressure device and manual to jaycar with you or they are guessing too.

Another option just get the original adaptor and live happily ever after.

Depending on battery size a charger set may be economic and useful.

JimmyH

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Reply # 1979467 18-Mar-2018 20:54

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If you are sure that the voltage is correct, and that the current output is sufficient, then you should be able to get away with just buying the correct plug from Jaycar, instead of a whole new adapter. A new plug shouldn't cost that much, assuming it's a fairly standard one.

Then cut the old plug off, solder the new one on, double check that you have the polarity the right way round, and you are good to go.

Bung

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Reply # 1979480 18-Mar-2018 21:34

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JimmyH:
Then cut the old plug off, solder the new one on, double check that you have the polarity the right way round, and you are good to go.

I suspect that if the OP was in a position to do any soldering and polarity checking this thread wouldn't have started.

Jaycar do have adapters 2.1/2.5mm socket to 1.3/2.1/2.5mm plug (PA-3700 - 3706)

hio77

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Reply # 1979481 18-Mar-2018 21:47

richms:

The reason that they do the different plug sizes is to stop incorrect ones being used from within their own product range, since people will just pick up a sony adapter and try to plug it into a sony appliance etc. Between brands there isnt really a standard. There was supposed to be with the yellow tipped ones but that didnt work out at all with companies doing their own things with the variaty of new sizes that came with the yellow plugs. Now I have seen blue ones on other gear, not sure how they differ from the others as far as size goes, but the whole idea is to stop wrong ones being connected.

there are a few oddballs out there.

fritzboxes for example, take a different jack to 95% of modems...

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Tinshed

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Reply # 1979482 18-Mar-2018 22:06

Bung:
JimmyH:

Then cut the old plug off, solder the new one on, double check that you have the polarity the right way round, and you are good to go.

I suspect that if the OP was in a position to do any soldering and polarity checking this thread wouldn't have started.

...

Quoted for truth. I really don't understand electricity at all, despite having several people explain to me voltage, wattage, ampage, resistance, ac, dc, Uncle Tom Cobbly and all. Nah, my brain isn't wired that way :-)

Tinshed
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gzt

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Reply # 1979484 18-Mar-2018 22:28

Bung: Jaycar do have adapters 2.1/2.5mm socket to 1.3/2.1/2.5mm plug (PA-3700 - 3706)

Nice! Once again, take the device, manual, and the existing adaptor to jaycar. The converter above is $3 if everything else is equal.

Bung

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Reply # 1979516 19-Mar-2018 08:28

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If the BP device is an Omron it takes a 4mm OD x 1.7mm ID plug (same as old Sony Walkman).

If the purchased power supply was a 5.5mm x 2.1mm plug this should work
https://preview.trademe.co.nz/marketplace/electronics-photography/tvs/other/listing/1569462933

robjg63

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Reply # 1979576 19-Mar-2018 09:42

Even worse - why are there so many odd voltages, odd plugs, different polarity plugs etc etc...

If you are unsure about power supply requirements maybe you are safer buying the 'proper' unit.

What sort of BP unit have you got?

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Tinshed

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Reply # 1979579 19-Mar-2018 09:45

Bung: If the BP device is an Omron it takes a 4mm OD x 1.7mm ID plug (same as old Sony Walkman).

If the purchased power supply was a 5.5mm x 2.1mm plug this should work
https://preview.trademe.co.nz/marketplace/electronics-photography/tvs/other/listing/1569462933

Yes, I will be popping into Jaycar this week with my Omron and the plug I bought and see if I can get the adapter mentioned.

Tinshed
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Bung

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Reply # 1979611 19-Mar-2018 10:15

AFAIK Jaycar don't have that particular adapter. Google shows Trzdeme and a couple othdr options. If you didn't already have a 6v plug pack I'd suggest trying a USB to dc plug cable (various size tips) with a 5v phone charger. The Omron might show the batteries not fully charged icon on screen but would still work.