Versatile Power Station

[UK-Corlett]

Hi All, this is what I have been up to reciently.

I have posted two of the components which I thought others may be interested in in more detail elsewhere on this forum.

I wanted to keep my power requirements low key and low voltage. I wanted some lighting (12V or 5V) a small battery driven hi-fi (2xAA batts =3V), to charge my mp3,phone,palm (5V mostly charge off a computer USB) and to drive a solar powered extractor fan when there was no sun (1.2V).




It should run from 2x7Ahr batteries, must be small, serviceable and fused. I can use Batt No1 or No2 and charge batt No1 or No2 indipendently.



This is my Battery charger it’s an LM317 giving 13.8V current limited to 300mA. It also has a thermistor-controlled fan, which only comes on when things get hot.



This is my voltage board. It takes 12V ish and gives out 2 Amps of 5V which can be cut down to 3.3V and 1.2. Notice the USB headers.



I have a PDF of this schematic so you could read it better but no where to put it to link too.



I have now fitted it to the TD and it fits just fine. Now for that kitchen I must get a couple of sheets of 8'x4'x1/4" Beach ply.

Clive

[Caradoc]

Very nice. It's always good to see people making their own circuits -- it seems to be getting more and more rare. Very sharp looking.

--Lance

[48Rob]

Clive,

It looked very do-able for me until I saw the picture of the inside...
and then the wiring diagram... I'm impressed with your ability!

Think I'll just stick to making things from wood

Rob

[Caradoc]

Now that I'm home, I've had a little more time to look over your schematic. I'm more of a software guy than a hardware guy, but the voltage board seems pretty straightforward, and actually is a pretty good idea, especially since it gives you the nice USB power.

In your schematic, the circuit at 9 o'clock seems to be the battery charger. I've got a couple of questions, since I've never built a circuit like this before:

• Why did you use an LM317T over some 7812 regulator? Is having it variable worthwhile?
• Is there a problem piping 12v back into the battery?

Is the 7 o'clock circuit with the op apm your fan controller? Is there something more to that that I'm missing?

Otherwise, very nice. You almost need a piece of acrylic over it so you can see inside showing your handiwork.

Thanks.

--Lance

[ARKPAT]

Caradoc Posted: Tue Feb 27, 2007 11:25 pm Post subject:

--------------------------------------------------------------------------------

Now that I'm home, I've had a little more time to look over your schematic. I'm more of a software guy than a hardware guy, but the voltage board seems pretty straightforward, and actually is a pretty good idea, especially since it gives you the nice USB power.

In your schematic, the circuit at 9 o'clock seems to be the battery charger. I've got a couple of questions, since I've never built a circuit like this before:

Why did you use an LM317T over some 7812 regulator? Is having it variable worthwhile?

Is there a problem piping 12v back into the battery?

Is the 7 o'clock circuit with the op apm your fan controller? Is there something more to that that I'm missing?

Otherwise, very nice. You almost need a piece of acrylic over it so you can see inside showing your handiwork.

Thanks.

--Lance

Lance I think Clive is using the LM-317T (TO-220) for a charger to supply 13,8 V D.C. to charge the batteries at a limited current of 300ma. The batteries are used to supply voltage and current to all of the other circuits. You could use an LM-7812 to get a regulated 12 V D.C. and a LM-7805 to get the regulated 5 V D.C. voltages for the various circuits. Also you can use another LM-317 (TO-92 ) for the 3.3 V D.C. Clive is doing the same thing with the other IC's in the circuit as the LM-7805 would.



Clive I like the design and layout of your circuit.



Pat

[UK-Corlett]

Hi All; thanks for the kind words.

Hi. Lance (Caradoc)

Fist things first. I am a mechanical engineer, where electronics are concerned "I can talk the talk" but i have difficulties "walking the walk".

I have relied heavily on borrowed circuits and stitched them together as best as I can. The switched logic and the practical build is no problem its just like grown up LEGO. But why the circuit uses one type of opamp over another I have not a clew.

Q why the LM317. I understand it to be a common voltage regulator that you can vary the supply voltage and current limit it and its cheap.
Q Yes the circuit at 7 o'clock is a fan control.

I have found inspiration at the following web sites, a must for any one interested in adding some electronic function an it's fun, well i think so.

http://www.hobbyprojects.com/
http://www.uoguelph.ca/~antoon/circ/circuits.htm

A lot of good stuff has been done by "Jan Hamer" but his site is in Dutch, not the easyest language.

Clive