DIY power hub

[Daz69]

Just ordered a load of bits to make my own 12v power hub. To start, I'll use a 12v 9ah SLA deep cycle battery. There will be a press to operate switch to display the voltage via a small LED voltage display. There will be 4 sets of 12v banana sockets using PWM, and 1 set of 5v banana sockets direct voltage. Finally there will be 2x 12v cigarette sockets. 

I ordered 2x 12v PWM dimmers

which I'll remove from their cases and adapt to fit my project box, and each of these will power 2x sets of banana plugs for heaters. I'm thinking 2 for the scope (secondary and EP) and 2 for something like the EP case and a seat pad???

The 5v will be for a primary fan. The cigarette sockets will be for a phone charger and the red LED strip light.

Anything else I should be thinking of? I'll be using 7805 and 7812 voltage regulators for the power sockets, and caps for smoothing the supplies, but this may change once I open the PWM's as I believe there should be some inside anyways.

I'll be making my own heather elements using nichrome wire.

[RayD]

Good stuff.  I built my own box and it was a good bit of fun.  I'm not sure I can get my head around the need for PWM dimmers and a 5v fan when you have a 12v battery?

Don't forget a 9ah battery really isn't very big, so this isn't going to power an awful lot.

[iapa]

30 minutes ago, RayD said:

Good stuff.  I built my own box and it was a good bit of fun.  I'm not sure I can get my head around the need for PWM dimmers and a 5v fan when you have a 12v battery?

I though that you would want to be able to adjust the power to the heaters - dont want them to get warmer than you really need or you could  introduce air currents?

Certainly what I was planning of mine - variable control for heaters.

[RayD]

14 minutes ago, iapa said:

I though that you would want to be able to adjust the power to the heaters - dont want them to get warmer than you really need or you could  introduce air currents?

Certainly what I was planning of mine - variable control for heaters.

Ah ok makes sense.  Yes you would want to control the dew heaters definitely.  My dew controllers are separate, so didn't give that a thought.

If you are running a fan, I would have thought the most energy efficient way would be a 12v one but I guess you've done your planning and this works best.  Be good to see the results.

I put a little twin USB port on mine which has a built in 12v - 5v convertor, which works a treat.

[Daz69]

Yes, the dimmers are for the heater controls. I use the same sized battery in my power box that I use for night fishing, and that runs a 12" LED bar and charges my phone and tablet. It lasts for ages, but irrespective, when I get home I stick it on the 4 stage charger.

I will charge the battery via one of the cigarette sockets.

The 5 volt will initially be a test output to run a 12v PC fan to see how much it puts out. If not enough then I'll use a 12v regulator, or even a 9v one (might actually go this way first). Not sure I'll need any USB sockets as I usually use one of those cigarette socket/USB adaptors when fishing, and I'm happy with that. 

 

[cjdawson]

Here's the box that I use for my scope.

The quick run down goes like this...

1. 4 * 12V marine cigar sockets  - the marine version accepts the both the car and marine plugs.  The marine ones have bits that allow the plug to lock into place.

2. 2 * 2 USB sockets (with switches) These will supply 2.1Amp of power to each USB port.  So it's good for charging Phone, Tablet and a couple of spares.

3. 12v volt and ammeter + battery status indicator (switched)  This lets me see the amount of power left, also the current voltage and the current.  It can cope with 50Amp through put.

4. XLR socket on side.   This goes to another box, I'll talk about this in a moment.

5. XTC-60 connection - this is there to allow me to connect a second battery in parrellel, more power!

6. Jump starting terminals - this really here to allow me to charge the battery up without taking it out of the box.

7. 150W inverter (It's inside the box) - yep. 240 Volt power is available for running a laptop etc.

 

The battery inside is a 70Ah leisure battery from Halfords.   It's wrapped in insulation.   In addition the wiring inside the box is all rated to 50 Amp, although I'm only likely to be using about 15 Amp at full load.  There are copious amounts of fuses too.

 

The XLR Socket on the side is used to connect my battery to this box.

This box runs from a single 12V input (the XLR Socket) and whilst this picture shows the incompleted version, it's easier to explain it's use.

The box contains 2 6Amp PWN circuits (From vellman) and currently a 12-5v DC-DC voltage convert.

It uses a 9-Pin D socket to output the following.

2 * dew heater element circuits.  This takes up 4 of the 9 pins.

12v output.

5v Output

Ground (one pin used to be common to all devices)

This leaves 2 pins available for other things.   I'm thinking about adding a 8v output to be able to power a dSLR.

 

Here's what the box looks like with the lid on.

 

 

This in turn connects to another box...

This box is attached to the side of my telescope with Velcro, and provides the main power distribution.

2 * Dew heater elements.  I used 3.5mm phone jacks.  However, I'm thinking of changing them to RCA plugs, which seem to be the standard for dew heaters.

3 * 12v 2.5mm DC sockets.  One of these is used to power my telescope, the others are not used, they are available for future updates.   One possible use is if I decided to start using my Meade DSI camera again, I'll use one of the outputs to power the cooling fan.

1 * 5v output.  I put this in, so that I could power a SkyWatcher Synguider.     I since wished I'd put 2 in the box, so that I could also power my SkyFi.    However, I've changed my autoguiding and no longer need either device.

 

Inside the this box there are 3 fuses, these are connected to each of the 12v sockets.

 

The idea of this appoach is to allow for as much flexibility as possible.  The box on the scope means that with one cable detachment, I can strip down my scope quickly.  (I leave everything installed all the time, weights about 25Kg, but it's lugable for me)

The box with the PWM circuits in means that I can adjust the dew heaters without any risk of making the scope wobble during an exposure.

Finally the battery box, is big powerful and has all the outputs that I am likely to ever need.

 

Future upgrades.

I'm thinking about adding an 8V circuit, to power a dSLR.  When I do this I'm going to completely redesign the box on the telescope.  It's a little too big.

The way that I'm going to make it smaller is to build a single PCB with all the components mounted directly to the board.  This will mean that I can place the sockets closer together and make better use of space.

It should also mean that I'll be able to have more items on the board.

[Daz69]

Wow, that's mighty impressive! I'm just doing a small box at the mo just for dew heaters and charging of tablet/phone. When (if) I get a goto mount and get into AP, then I'll have to make a more substantial box that will utilise my 110A caravan battery (on a trolley) if I ever go away from home, as well as 240v for quick plug in when at home, which will be the majority.

Thank you for sharing this with me. I may have to ask you some questions at a later date if possible? I'm still waiting on some parts to arrive for my box. Even if I do eventually make a more substantial box, this one won't go to waste as I'll be able to use it when fishing away for several days.