Eliminating multiple PSUs

tnegun

Hi all,

I've got multiple 5v, 12v and a 19v PSUs powering a cable modem, wireless router, 2x Raspberry Pi's and soon I'll be adding an Arduino clone to control the heating. All are or will be supplied by individual PSUs and are physically beside each other.

I was thinking of powering all the 5v devices from a multiport USB charger but now am thinking of eliminating the 12v & 19v PSU's for the modem and router as well. So I need a single PSU with multiple outputs is there such a device?

Will there be any significant energy saving from eliminating the additional PSU's? These all typically run 24x7.

Thanks!

ZENER

Be sure that the USB charger is capable of powering all the devices connected to it, here is the power requirements of the Raspberry Pi. Be sure to allow extra for any relay boards etc.

For the 12V and 19V you could get something like a laptop PSU to supply the 19V and connect a regulator to it's output to also provide 12V. How handy are you with a soldering iron ?

Ken

whizbang

Golden opportunity for a UPS/Backup solution. Wifi/Router absolute must. Look on ebay for a 12-19v inverter, then power everything off a decent 12v battery with charger.

If you are worried about power consumption, you would have to check specs of the power supplies you have currently. If they are anyway green, any analog regulator will kill any saving you are aiming for..

Solar charger!! -might as well wire 12v led lighting everywhere so!!!

tnegun

ZENER wrote: »

Be sure that the USB charger is capable of powering all the devices connected to it, here is the of the Raspberry Pi. Be sure to allow extra for any relay boards etc.

For the 12V and 19V you could get something like a laptop PSU to supply the 19V and connect a regulator to it's output to also provide 12V. How handy are you with a soldering iron ?

Ken

Its a 4 port charger and puts out 2 amps so it should do it. I'm ok with a soldering iron how are you thinking of putting it together?

whizbang wrote: »

Golden opportunity for a UPS/Backup solution. Wifi/Router absolute must. Look on ebay for a 12-19v inverter, then power everything off a decent 12v battery with charger.

If you are worried about power consumption, you would have to check specs of the power supplies you have currently. If they are anyway green, any analog regulator will kill any saving you are aiming for..

Solar charger!! -might as well wire 12v led lighting everywhere so!!!

I've got a relatively new unused UPS but I stopped using it I wanted to cut electricity usage at night I can get back to about 150w and 60 - 80 of that are the PSUs I want to eliminate. What am I looking for on the PSUs to determine if they are green? I thought that having multiple small PSUs would be inefficient than having a couple of larger ones supplying different voltages.

I been looking at something like this - I can't link but google "AC to DC Power Supply Dual Output 24 Volt 12 Volt 5 Amp 7 Amp 133.2 Watt" its on jameco dot com - I was thinking this would be perfect I'd get 19v using the 24v rail and 5v rail as ground and I have the 12v and 5v from it but I don't know how to put something like this together to actually deliver the power to the device and I don't want to cut up the existing PSU's (Most of my knowledge comes from Google and an Electronics module I did in college 17 years ago!!)

tnegun

Actually search for this one Par tno RT-85D "AC to DC Power Supply Triple Output 5 Volt 24 VOLT12 Volt 10 Amp 2.5 Amp 1 Amp 90 Watt" its the one I was looking at.

tnegun

Or this one on aliexpress Triple output power supply 50w 5V 12V 24V 3A 1A 1A power suply T-50D meanwell ac dc converter good quality - Store no 521261

Johnboy1951

One 19V power supply and a small board in a box with 12V and 5V regulators ...... and power the lot from the one source.

Make the box a bit bigger and put the 19V PSU inside for an even tidier result.

You would need to estimate the highest current draw for each device and ensure your main PSU can supply the combined worst-case power draw.

cable modem,
wireless router
Raspberry Pi
Raspberry Pi
Arduino clone

Johnboy1951

Johnboy1951 wrote: »

One 19V power supply and a small board in a box with 12V and 5V regulators ...... and power the lot from the one source.

Make the box a bit bigger and put the 19V PSU inside for an even tidier result.

Still multiple PSU's just all inside one box.
It is the neatest.

I was thinking server PSU's in series and "centre tapped". Bit dodge though, need to earth them right and drop the 24v to 19V.

whizbang wrote: »

Golden opportunity for a UPS/Backup solution. Wifi/Router absolute must. Look on ebay for a 12-19v inverter

Boost regulator. An inverter changes DC to AC.

UPS have a high self-consumption and no self preservation skills they can destroy batteries. A lot of them won't cold start either, mains has to be present at boot or you need an inverter to charge the caps.

whizbang wrote: »

then power everything off a decent 12v battery with charger.

You'll be introducing battery charge inefficiency here although not a factor if running from PV, it's an expensive and elaborate route.
Still needs regulators on all the fixed outputs. Chargers and batteries make less than ideal voltage sources.

I do like the idea but perhaps over-engineered...perhaps not..

whizbang wrote: »

Solar charger!! -might as well wire 12v led lighting everywhere so!!!

Everywhere is ambitious for 12V lighting. Factoring the price of copper versus voltage drop versus inverter cost and efficiency as a personal rule I'd use AC lighting or 48VDC if you're wiring a ring main bigger than 2 rooms. Much easier tap the existing system with an inverter too.

Johnboy1951

You might also consider using mains sockets with 2 built in USB charge ports which would power the R-Pi devices.

An example (not a recommendation)

http://ie.rs-online.com/web/p/electrical-sockets/7967363/

others here

http://www.screwfix.com/p/lap-13a-2-gang-sp-switched-socket-usb-charger-brushed-steel/18294

CountyHurler

I think boosting the 12v DC to 19V DC is just too much hassle.. I would look at replacing the 19V DC router with a 12V box.. I install these types of devices every day, and they are pretty much alll 12V these days.... The Eircom D1000s which are shipped with new broadband packages are 12V.. The older Zyxel 660HWs are also 12V.. And most of the Zywall boxes are also 12V... If your router is 19V, it must be a cisco 800 series or something is it?

You can then power the two 12V DC devices from the 12V rails, and power the 5V charger from the 5V rail (not the USB port)... this guy did a nice job of converting an ATX SMPS power supply in to a lab power supply... Another one of the projects on my "to do" list...

https://www.youtube.com/watch?v=z2oSFpKh_Uw

But you need to make sure that whether you're using the USB or the power rails from the PSU directly, that you are not exceeding the current usage... The USB will only deliver 350mA at 5V...

ShRT

If you go down the route of regulating down from a higher voltage, make sure to avoid the likes of the 7805 regulators. They are tempting for their simplicity but are not that efficient.

You should use a buck convertor instead as they are very efficient.

For the Arduino heating system control, you should power the Arduino from 5v directly to VCC. This will avoid using the linear regulator that is onboard which is actually a large consumer of an arduino's current usage. It will also mean that if you use the Arduino's sleep functions, you will be able to further reduce power consumption. If you are sampling the temperature for example, you can take a reading, then put the Arduino to sleep for 5 mins and then wake to take the next reading.

tnegun

Thanks for the replies guys. I've done some rationalizing and dropped a Pi from the equation I've also got 3 usb ports to play with on the router and cable modem. One of these is powering the Pi so hopefully I've ruled out a need for 5v.

I've sourced an old printer PSU and it delivers +/- 12v and 5v so was thinking of using it. With the extra devices I need to add a switch to the mix and it's PSU is 15v. So now I need
19v, 15v, 12v and 5v(Hopefully from an existing USB port).

I've actually converted an old PC PSU as a bench supply but it's a bit ungainly so was hoping for a tidier solution.

The rating on the existing PSUs is 19v 1.6a(30w), 15v 1.5a(22w) and 12v 1a(12w). I'm right in thinking this is the maximum and the devices should draw less right? Worst case this is 500-600 kwh per year. I'm just trying to get a handle on what savings if any I will achieve as these and eliminating clutter are my main objectives!

tnegun

tnegun wrote: »

I'm right in thinking this is the maximum and the devices should draw less right?

Right

tnegun wrote: »

Worst case this is 500-600 kwh per year. I'm just trying to get a handle on what savings if any I will achieve as these...!

Measure it at the plug with your typical load running if you want to know the actual draw.