# Help needed please, component and wiring

#### JRthemoon

Joined Mar 11, 2021
9
I and my son are Autistic, Asperger's and he also has PTSD.

I am retired (62) and he is unemployed 23.

We have designed something that is being bought by a company, hand built in Wales.

It has a vibrating motor, 12v supply and a variable speed.

However the problem is that to change the batteries we have to remove the top, annoying to users.

We can not locate a similar size case with a battery compartment, 52 mm, 155 mm, 180 mm

We thought we could place an extra female input on the side that cuts off the internal power when connected, ANY ideas, advice as to what would be so very much appreciated

Thank you

#### LesJones

Joined Jan 8, 2017
3,476
A normal 2.5mm (Or 2.1mm) low voltage panel connector should do what you require. This is one example but you can probably find them cheaper. I chose this ebay entry as it has a picture of the connection side of the socket. The center pin is normally used as positive. The negative side includes a set of changeover contacts that disconnects the battery negative when the power plug is inserted and connects the load to the power from the connector. You will probably be able to find them cheaper. If you want them from a normal supplier you could try CPC, Farnell or RS components.

Les.

#### JRthemoon

Joined Mar 11, 2021
9
YEY many thanks,

Is " 2.5mm (Or 2.1mm) low voltage panel connector " what I look for

#### AnalogKid

Joined Aug 1, 2013
9,351
Is there a circuit board inside the case? If so, a possibility is getting a power connector that is pc mounted with the other components, and just peeks out through a hole rather than being physically mounted to the case.

ak

#### Marley

Joined Apr 4, 2016
416
What type of internal battery does it use?

#### LesJones

Joined Jan 8, 2017
3,476
I found them on Farnell's website by searching for "2.5mm power connector" I then selected Power Entry Connectors which took me to this page . AK makes a good point about mounting them on your printed circuit board if you are using one. I imagine you are using PWM speed control so you may be manufacturing that yourself. If this is the case it would save the step of hand soldering wires between the board and the connector. Although I said the center pin is usually used for positive this NOT ALWAYS the case. If you plan to provide a power supply with your product make sure you wire the polarity to suit. Also mark the polarity, voltage and current on the case near the connector.

Les.

#### JRthemoon

Joined Mar 11, 2021
9
What type of internal battery does it use?

Idiot I am 8 x aa in a battery pack

#### DickCappels

Joined Aug 21, 2008
7,689
Looks like a good choice for 8 volts

#### Tonyr1084

Joined Sep 24, 2015
6,243
Wouldn't 8 cells be 12 volts?

Question for JRthemoon how long does the 8 batteries last?

#### MrSoftware

Joined Oct 29, 2013
2,015
If you want to go the external plug-in route, some female barrel connectors have the option to cut off a circuit when they are plugged in. The audio barrel connectors in particular have this, maybe some of the power ones do too. If you want a new enclosure, check out Polycase, or a place similar if you need something closer to home. They have a pile of enclosures to choose from, and they can machine and print them. I've used them for multiple products. They are not cheap but the result is excellent, which might help you sell the product.

#### BobaMosfet

Joined Jul 1, 2009
1,848
@JRthemoon You have 12V internal. Simply add a few components to allow you to use a 12V wall adapter to provide external power, and then the batteries will serve only as a mini UPS if wall-power occasionally drops.

Here's how:

Battery Pack positive in series with a 1N5818 Schottky diode - Anode towards the positive side of battery pack. Wall adapter positive from a 5mm DC barrel jack attached to the Cathode side of the 1N5818 (basically putting both power-sources in parallel, but the diode prevents the wall-power from charging the batteries.) The diode also drops the battery power to less than the wall paper, by about 0.33-0.55V, so that the wall power will overcome the battery power, whenever it is connected to wall power. Then connect the positive input (where the two power-sources connect after the diode) to your power-switch (a cherry rocker switch or something), and the output from the switch then goes to your downleg voltage regulator. I also put a fuse in, but I don't know what your current requirements are so you'd have to choose an appropriate fuse (F1) for that.

Incomplete Example to show it:

The above also has a green LED power-indicator so that it can easily be seen whether or not the device is ON/OFF. I have a 5V regulator for PCB logic, but I don't know what your needs are so you'd have to change it. If you get fancy, you can add a few extra components to allow you to test the battery and keep and eye on its state.

You can use an Uxcell (#A18050500UX0132) barrel jack mounted to your PCB, and a 6.xmm hole in the case:

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xox

#### MisterBill2

Joined Jan 23, 2018
9,235
I consider the power connector soldered to and supported by those solder connections to be a very cheap and inferior arrangement.The reason is that bumpng and wiggling the plug leads to the connections of the soldered portions breaking. FAR more reliable is the incoming power connector that uses jam nuts to hold it in place., and wire leads for the connections to the PC board.

#### JRthemoon

Joined Mar 11, 2021
9
Here is what my Autistic son developed the problem is that the case has to be PULLED apart to replace the batteries hard for many disabled, we can not find one with a battery compartment. 180x150x55 approx

#### LesJones

Joined Jan 8, 2017
3,476
I was interested to know what it was used for and I found out with an internet search. I was surprised that anyone still developed film. The last time I developed a film was about 60 years ago when I was 16 It was ferraniacolor reversal film. This took so much more time than black and white film that decided it was much easier to buy colour reversal film and pay for proccesing.

Les.

#### MisterBill2

Joined Jan 23, 2018
9,235
One method of solving the battery replacement challenge will be rechargeable batteries and an external charging connector, such as those very standard barrel connectors. A regular audio style connector is a very poor choice because it is always short-circuited during insertion and removal.
Yes, I am aware that this may have been mentioned already, but it is the one option that is reasonable. The other would be to replace the battery pack with an internal mains-powered supply. That might not fit.

#### Sensacell

Joined Jun 19, 2012
2,890
Batteries are horrible, miserable things, why not just plug the device in?

You don't process film 'on the run' - so why does it need to be battery powered?

#### Yaakov

Joined Jan 27, 2019
3,464
A regular audio style connector is a very poor choice because it is always short-circuited during insertion and removal.
As an aside, I have a personal rule never to supply power through connectors that are expected to have low level signals on them, and never to use connectors expected to have power on them for low level signals.

There are so many options for connectors that using them in this way is not necessary and can lead to some pretty spectacular end of life events for devices.

#### MrSoftware

Joined Oct 29, 2013
2,015
Unless it needs to be super portable, I would agree that plug-in, or at least a plug-in option would be nice.

That said, if it's pre-production, why not choose a box with flip up latches and a hinge? Maybe not this exact box, but something that opens like this:
https://www.polycase.com/wq-48

#### dl324

Joined Mar 30, 2015
13,082
We thought we could place an extra female input on the side that cuts off the internal power when connected
Male connectors are more typical. I've never seen a female connector used for power.
Is " 2.5mm (Or 2.1mm) low voltage panel connector " what I look for
I've found that 2.1mm x 5.5mm is more common in power adapters. I've bought these on Ali Express for less than $0.15 each. Again, male connectors. #### Yaakov Joined Jan 27, 2019 3,464 Male connectors are more typical. I've never seen a female connector used for power. I've found that 2.1mm x 5.5mm is more common in power adapters. I've bought these on Ali Express for less than$0.15 each. Again, male connectors.
Coaxial power connectors can be confusing. The male has a sticky-out bit that is hidden and the female has the sticky-in bit hidden. People don’t know the female gets stuck into the male, which seems backwards if you don’t know how the taxonomy of connectors works. XLR connectors is another example.