5volt to 12volt converter

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kebang
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5volt to 12volt converter

Postby kebang » Mon Jan 14, 2019 8:18 am

https://www.lazada.com.ph/products/dc-d ... i&search=1

To save connecting a power supply to the mains (outlet in inconvenient location) I'm thinking of buying this and connecting it to a powerbank and then to a single train controller. Opinions welcome as to if this is viable :D

Paul-H
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Re: 5volt to 12volt converter

Postby Paul-H » Mon Jan 14, 2019 8:58 am

How much are they

As long as you don't need more than about 1 Amp you could build one yourself with a 99p buck converter found on the likes of eBay, I built a couple myself for powering cameras on location, they were turned down to 7.4v but IIRC the buck converters could boost to 24v being fully adjustable.

Something like this one would do the job

https://www.ebay.co.uk/itm/5V-9V-12V-Bu ... 3378484068

Paul

kebang
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Re: 5volt to 12volt converter

Postby kebang » Mon Jan 14, 2019 9:32 am

Approx 2 quid + 1. 50 postage, so if it will work its not worth me trying to build anything... I suppose I should have phrased my question better! Is the output going to have enough amperage to power a modern 4 wheeled Hornby loco?
If the answer is a 'definitely no' I won't pursue it, but at that price if the answers are 'possibly' or 'probably' I'll try it

Paul-H
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Re: 5volt to 12volt converter

Postby Paul-H » Mon Jan 14, 2019 4:58 pm

For £2 what have you got to loose, it should be safe for around an Amp so should be good for a modern Hornby even there big locos pull well under an amp

You could use it with one of those £2 PWM controllers on ebay as well https://www.ebay.co.uk/itm/6V-28V-3A-80 ... 2632223606

A portable PWM controller for under a fiver

kebang
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Re: 5volt to 12volt converter

Postby kebang » Tue Jan 15, 2019 12:30 am

One of those PWM controllers arrived at my home last week Paul and, as you suggested, I'm looking for a way to make it completely self contained & portable!

Gordon H
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Re: 5volt to 12volt converter

Postby Gordon H » Tue Jan 15, 2019 4:46 pm

Paul-H wrote:How much are they

As long as you don't need more than about 1 Amp you could build one yourself with a 99p buck converter found on the likes of eBay, I built a couple myself for powering cameras on location, they were turned down to 7.4v but IIRC the buck converters could boost to 24v being fully adjustable.

Something like this one would do the job

https://www.ebay.co.uk/itm/5V-9V-12V-Bu ... 3378484068

Not really. What you need is a boost (step up) regulator, not a buck (step down). That one is a step down only.

kebang
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Re: 5volt to 12volt converter

Postby kebang » Thu Jan 17, 2019 8:07 am

I've ordered a 20000ma powerbank and one of the 5v to 12v cables. I'm looking forward to seeing if it all works or not :)
Assuming a little loco draws 400ma is there any way of calculating how long it will take to drain the powerbank, or at least making a rough estimate?
I'm no electrician but I'm thinking that the 20000ma should be divided by 12v then multiplied by 5v, giving 8333ma. I think there will be system losses, but I'm hoping this will allow for around 4hrs loco operation. (Although if my thinking is correct we should divide 8333 by 400 which would give over 20hrs use, which seems most unlikely!)
Can anyone with a greater knowledge of electrics than me (which is probably everyother forum member!) make a guess?

Paul-H
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Re: 5volt to 12volt converter

Postby Paul-H » Thu Jan 17, 2019 11:10 am

The 20 hours is probably a theoretical running the battery flat scenario which you don't want to do and probably cant do if the power bank is designed properly with built in protection.

not going to comment any more as pointed out above i don't know my bucks from my elbow :wink:

kebang
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Re: 5volt to 12volt converter

Postby kebang » Fri Jan 18, 2019 4:32 am

Just hoping I get more than 2 hours running time before I need to recharge the powerbank! As you can see from my deliberations above I have no idea what the method should be used to calculate the running time. :?

Paul-H
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Re: 5volt to 12volt converter

Postby Paul-H » Fri Jan 18, 2019 6:42 am

I suppose the limiting factor is just how accurate the seller is over the claimed 20000ma battery, if you got it from eBay then expect it to be closer to 2000ma or even less. 20000ma would be quite a big heavy pack, can you post the dimensions and weight of your pack, or a link to the seller.

kebang
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Re: 5volt to 12volt converter

Postby kebang » Fri Jan 18, 2019 7:01 am

https://shopee.ph/COD-Romoss-Sense-6-20 ... 1229122292
It costs less than 4 quid so I can't expect too much!

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TimberSurf
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Re: 5volt to 12volt converter

Postby TimberSurf » Fri Jan 18, 2019 7:05 am

Kebang, your electrical maths is correct, in theory, it should give 20 hours, but as said, ratings from ebay batteries tend to be inflated, I would be surprised if you didn't get 10 hours out of it. :D
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Paul-H
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Re: 5volt to 12volt converter

Postby Paul-H » Fri Jan 18, 2019 8:20 am

Its physically impossible for a pack that small to come anywhere close to 20000mah, going by the size I bet its closer to 2000 than 20000.

Paul

kebang
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Re: 5volt to 12volt converter

Postby kebang » Fri Jan 18, 2019 10:28 am

I'm surprised my electrical calculations are right TimberSurf! (But of course no allowances have been made for system losses etc.)
Paul - When I look at the size & weight of a 2AH 6v motorcycle battery I do wonder how they can claim to have encapsulated 20000ma into this inexpensive little device at a quarter of the price! I think you are right, 2000ma seems more likely (which means I'll be lucky to get 1 to 2 hours running time)
Still the proof of the pudding is in the eating! If it isn't useable at least I'll have a powerbank for my phone :lol:
When it arrives I will post the result!

Paul-H
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Re: 5volt to 12volt converter

Postby Paul-H » Fri Jan 18, 2019 10:58 pm

For the price you could always buy 10 of them and either change them as the go flat or link them all together and make your own 20000mah pack.

Paul


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