How to create a USB charging cable?

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Old 12-15-18, 01:47 PM
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How to create a USB charging cable?

I purchased the Ring security system with the keypad using micro USB charging cable. My existing unit is a Simon XT and it uses a 9v AC adapter. Is it possible to convert the other end of this cable to a male micro USB cable so I can charge my Ring keypad unit? I'm trying to avoid running new wires inside the walls to charge my Ring keypad unit if I can use the existing red and black wire from the 9v AC.

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Old 12-15-18, 01:52 PM
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The micro USB has 5 pins. The far opposite ones are 5 VDC.

https://www.neverstopbuilding.com/bl...cro-usb-pinout

You will also need a 5V DC, Class 2 power supply; like about 1Amp. How long is the existing wire run? There will be some voltage drop. At 5V that could be significant.
 
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Old 12-15-18, 01:56 PM
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The wire is about 32feet. So at this point, I can't convert to USB with what I currently have then, correct?
 
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Old 12-15-18, 02:42 PM
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Correct. A 9v AC adapter will not work.
 
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Old 12-15-18, 02:45 PM
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What if I created my own custom micro USB charging cable? What type of wire should I purchase and where do I find the USB terminators online? If I can't use the existing 9v AC adapter with a red and black wire, I think I can tie the existing wire to the new wire/cable and pull through then terminate the two ends to regular USB and one to micro USB. One of the reasons I am thinking about creating my own custom USB is that the existing hole is small (only fit the two red and black wire) so if I purchased an existing 32 feet USB cable, the end may not fit the existing hole to pull through.
 
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Old 12-15-18, 05:04 PM
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Re-using the wires is worth a try,
my quick calculation suggests 32 feet should still get about 4.9 volts.

What is the amperage requirement for the Ring? See if you have an old usb charger with the same power output.

Take an old micro-usb cord you're not using, cut it in half, connect the usb cord to white wire, (red-to-red and black-to-black), and connect the other end. Should work.
 
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Old 12-15-18, 06:16 PM
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The wire is about 32feet.
At that point, the voltage may be pretty low depending on how much current your keypad is putting.

If there is a junction box or space for some sort of project box, you can supply 12V DC to it, then convert to 5V using DC to DC converter that you can buy on-line very cheap.
Some will come with USB port attached, so you don't even have to make your own cable.
 
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Old 12-16-18, 05:48 AM
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That is a good suggestion. What if I purchase a 32 feet USB extension cord, cut it at one end so that it fits the existing hole, pull it through using the existing cable, reattach it via soldering and bypassing the whole 9v AC adapter all together? Will this work?
 
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Old 12-16-18, 06:13 AM
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What are you going to feed that USB cable with?
USB cables are not designed to be used over such a long length of cable and it may contain even thinner wires then what you already have.
You will still have voltage drop.

It is hard to tell how much voltage drop you will have until you try.

https://www.amazon.com/HOMREE-Conver...2Bto%2Bdc&th=1

Use this and replace power adapter to 12V DC.
 
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Old 12-16-18, 07:27 AM
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Well, that does look like a pretty idea. So, I need to replace my current 9v AC with a 12v AC and then at the other end that goes into my Ring keypard (which it uses 5v micro USB) all I need to do is connect to the HOMREE DC-DC Converter Step Down Module, correct?

My other work-around is, I'm thinking about using the adapter that came with the Ring keypad.

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Old 12-16-18, 08:36 AM
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So at the receptacle, I would have this 12V40VA ( 12VAC 40VA ) Wall Plug Adapter Power Transformer and on the other that goes to my Ring keypad is the HOMREE DC-DC Converter Step Down Module. This will work in my situation, right?
 
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Old 12-16-18, 08:49 AM
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I need to replace my current 9v AC with a 12v AC
NO!
You need 12V DC. Not AC.
Not sure if they come with screw terminal, but there are plenty of 12V switching power supplies with cord with barrel connector on other side.. You can either cut the wire and and splice or purchase female connector with screw terminal on the other side.

You can make AC adapter work by adding a rectifier circuit, but that is not worth it in my opinion.
You need 4 diodes (or rectifier bridge) and a capacitor to build a simple rectifier.

If you have a micro USB cable that you are willing to sacrifice, you could try use 5V adapter and see if it works.
 
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Old 12-16-18, 08:55 AM
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I can't find a 12V DC wall plug adapter that has two screws so I can simply screw the existing red and black wire to it.
 
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Old 12-16-18, 09:00 AM
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Would something like this work?
https://www.amazon.com/TFDirect-Regu...r+supply+3+amp
 
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Old 12-16-18, 09:06 AM
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Old 12-16-18, 09:17 AM
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The first one you linked is fine. You are probably fine with 1A as well.
You may have some laying around already from things like old cable modem, old router, etc.. 12V power adapter is very common.
You can feed anywhere between 8V to 20V on the dc to dc converter I suggested. So, go through your old adapters and see if you have something suitable.

You can use something like below if you don't feel like splicing wire.

https://www.amazon.com/dp/B015OCV5Y8..._t1_B01ER6QWAY
 

Last edited by lambition; 12-16-18 at 09:55 AM.
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Old 12-16-18, 09:28 AM
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lambition, that is very cool! I'll see if I can find any old 12v DC adapter laying around. Thank you so much for help. I'll give that a try first. If it works, I don't have to pull a new wire.
 
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Old 12-17-18, 04:29 AM
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Originally Posted by Charlie2
What if I purchase a 32 feet USB extension cord, cut it at one end so that it fits the existing hole, pull it through using the existing cable, reattach it via soldering and bypassing the whole 9v AC adapter all together? Will this work?
USB will probably have smaller wires than the wire you've already got in place. That transformer IIRC takes #20 or #22 wire, so the EXISTING wires in the wall are probably as big, or bigger (and thus better at carrying current ) than the wires in a USB 2.0 cable.

Remember, you're not making a "USB data cable" you're simply looking for a 5v DC power supply with a long wire. If the existing transformer outputs 9v AC @ 2.5 Amp (per GE Simon specs) that should be around a 30% voltage drop. Swapping to 5v DC @ .5 Amps is only a 10% drop (lower amperage helps).
 

Last edited by Hal_S; 12-17-18 at 05:03 AM.
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Old 12-17-18, 06:07 AM
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HAL_S, so another alternative is I could use my existing transformer (which was used with the Simon XT unit) and solder a micro USB connector at the other end for my Ring keypad?
Thanks for the response.
 
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Old 12-17-18, 07:04 AM
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Originally Posted by Charlie2
HAL_S, so another alternative is I could use my existing transformer (which was used with the Simon XT unit) and solder a micro USB connector at the other end for my Ring keypad?
No, the existing 9v AC transformer will fry the 5v DC Ring keypad.

Find a micro-USB 2.0 cable, cut it in half, use wire nuts to wire the two ends of the cable onto the two existing ends of the white cord, big connector at the transformer, small connector at the Ring. Wires go red-to-red and black-to-black, just use a wire nut until you know this works.

Connect a usb-micro by the ring, and the large connector on the side where the transformer was.
Instead of the AC transformer. look for a 1.0 amp USB power plug,

Most USB wall chargers actually run at 5.5v to 5.7v, which is good, because the voltage drop after 32' of #22 wire should still give you about 5v from the micro-usb connector at the Ring keypad.

Before connecting the keypad, check the voltage with a volt meter, should be 5v DC.
Plug in and see if it works.
If it works, then solder the wires, wrap with electrical tape and you're good to go.
 
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Old 12-17-18, 07:20 AM
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So even if the a USB cable has more wires than mine (red and black) I can just ignore those extra wires, correct?
 
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Old 12-17-18, 07:49 AM
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Originally Posted by Charlie2
So even if the a USB cable has more wires than mine (red and black) I can just ignore those extra wires, correct?
Correct.

I've taken old USB cords and spliced them onto 5v computer case fans without any problem, the wiring is quite simple, red-to-red and black-to-black is power.

Standard wiring shown below- red/black (power) and green/white (data)
 
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Old 12-17-18, 08:22 AM
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Awesome! That saves me a tone of work. Thanks!
 
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Old 12-17-18, 04:16 PM
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Most USB wall chargers actually run at 5.5v to 5.7v
It shouldn't be that high if they are properly made. Properly made ones are exactly 5V or slightly higher (something like 5.2V).

You probably will end up something like 4.6 to 4.7V at the end (with load connected). It may work just fine, but won't know for sure until you try.
If you end up with 4.6V or below, I would go for my original recommendation even if the device is working. Low voltage sometimes can damage electronics as well.
You have to measure with load connected to measure voltage drop.
 
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Old 12-17-18, 05:55 PM
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Originally Posted by lambition
It shouldn't be that high if they are properly made. Properly made ones are exactly 5V or slightly higher (something like 5.2V).
Sorry, should have been "cell phone chargers" because the older ones (e.g. nokia) with circular chargers were 5.7v, while the usb standard is 10%, so 5v-5.5v should still be within specifications.

So, an alternate solution, if a 5v DC usb charger doesn't provide 5.0 volts at the Ring side, then scrounge up a Nokia 5.7v charger, and use that to supply 5.7v DC to the system.
 
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Old 12-19-18, 04:37 AM
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Many thanks for all the help. I think I got it working now without re-pull new wires. So, here's what I have. A 12DC on one end with Female 2.1x5.5mm DC Power Cable Jack Adapter Connector Plug connecting to my 12DC adapter and on the other end I have the HOMREE DC-DC Converter Step Down Module 12V to 5V Micro USB Output Buck Power Adapter. So far it has been working.
 
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