Thread: Electronics O/T

What you need is a charge pump. Basically its an inductor (coil) a diode, a capacitor and a switch (fet power transistor or similar). The circuit amplifies the voltage so even a low input from the solar panel is always output at a fixed output voltage. Power remains the same (minus losses) so the current drops instead of the voltage.

I made one for my boat awhile back from a design froma frnch bloke which has now been commercialized :
Tunecharger : Battery and Energy Performance

Not sure if I still have the design stashed somewhere but google charge pumps should point you in the right direction

Cheers

You could use a DC to DC inverter with regulator. Solar panel inverters do just that. They increase the voltage of any output level to a regulated voltage, usually 13.8 for 12 Volt battery charging or 27.6V for 24 V systems etc. You just need to find one that sets the voltage for your pump. However, the current able to be drawn is obviously much lower at lower light levels and you pump may not be able to run at the low current levels available. That depends on the pump design.... A few variables to juggle there.

Joe

I have done a lot of reading and searching ebay but got confused - still confused actually.

The pump is brushless and it works as low as 2 volts so that is why I don't want to drop out the voltage at the lower levels. I don't want to run it on a battery as it adds cost and complexity and I don't want to pay a lot for the power regulation.

I'm working my way up to larger solar projects and using this as a learnng curve.

It's a mission with a novice that doesn't really know a lot about what they are doing.

Thanks for the leads and I'll read some more and hope the penny drops eventually.

I like your thinking

That is the sort of thing I want and will work in with my larger project.

So that my head has got around this the votage under 15 volts goes direct to the load - in this case the pump. Over 15 volts the relay opens and the incoming power is regulated to 15 volts then that goes to the load.
That means two set of wires to the same load - Am I on the same page?

mate had the same same problem , his solution had me shaking my head , a couple of solenoids were connected after a variable voltage regulators ( LM317) , over 12 volts a small solenoid shaded some cells to reduce the voltage on the solar panel , oscillation problems around the cut off point ,but who cares , the cut in cut out is variable

how many cells do you have to shade in full sun to get down to 14 volts

Originally Posted by rodm

I like your thinking

That is the sort of thing I want and will work in with my larger project.

So that my head has got around this the votage under 15 volts goes direct to the load - in this case the pump. Over 15 volts the relay opens and the incoming power is regulated to 15 volts then that goes to the load.
That means two set of wires to the same load - Am I on the same page?

sorry i thought about it and it was wrong , so i deleted my post while you were responding , the problem with the 13 volt DIAC tripping a single pole double through relay is the relay coil resistance has to be lower than the pumps , for the coil to work , but then most the electricity will go through the relay , then i looked into using IGBT's to switch the voltage but you would need 2 and then a TTL inverter , it gets complex , so i deleted my post

did a quick sketch and got rid of the DIAC

a LED voltage meter , could even use a LM317 voltage regulator , switches at 12 volts , triggering a relay
( might need to boost the coil amps with the LED meter , the 1.5amp voltage regulator wont need boosting , depends on the relay used )

the relay has NC / NO contacts , so you have a bypass relay side or when the coil is activated it runs the power through a group of resisters to drop the voltage , or a voltage regulator ( no 0 volts wire shown on relay / voltage meter)


edit
second drawing is with voltage regulators , they have only 1.5 amp out puts , so you might have to loose the 2nd one for the motor and use resistors to match the wattage of the motor ( ??/ 10x 1/2 watt ) need the ohms across the motor to work out the value of the voltage drop resistors



edit again
, in stead of voltage drop resistors you could run 2 pumps ??? wire them up + -, + - ( in series ) , connect the low voltage wire to the centre wire between the pumps so only 1 pump runs , and the high voltage wire so 2 pumps run , using the 2nd pump as the voltage drop resistor

the coil on the relay has to be less resistive than the motor , or bugger all power will go through the relay coil ???? depending on the pump it might be a problem
i like the lm317's , there adjustable , you could use dedicated 12 volt versions and do away with a lot of soldering , the LM7812 is the dedicated 12 volt regulator


there will be big voltage swings , if you have 19volts running 2 pumps both will run as if one was running 8.5 volts , as the voltage drops to 14volts this will be reduced to 7 volts each before the relay closes and shunts 13.8 volts into 1 pump down to 0 volts

with the resistors you can limit 19volts to 12 volts , but as the voltage drops to 14 volts , the pump will be running on lower voltage

the voltage regulator after the relay would be best as it holds the voltage at 12 volts until the relay shuts down at 13.8 volts , then dumps the 13.8 volts into the pump , you can amplify the output of the 2nd voltage regulator to run 10 amps , starts getting expensive

Here ya go, lots of ideas here.

Solar water pumping

Thanks for the ideas.
I set it all up last night and had to wait for some sunlight to see it working.
Looks like it is going to be a good day for solar so will disconnect it before it over voltages.

Sawdustsniffer,
I can see your mind running wild with ideas and I appreciate your input. I will sit down quietly and study your schematics as it takes a while for it to sink in for me.
I'll get back with the final solution.

as soon as i saw your water mill i thought of a "Pond Clock " water powered clock ? lol , just have to accurately time the pump to stop at 7pm and start back up at 7am ,

ive been thinking of a granite clock for a while , with water/ algae lubed bearings

Yeah my mind took me to driving a few gearotic gear trains but lots of other things I want to do so called it finished as it was. Leonie likes it and that is all that mattered.

Too many ideas and not enough time to do them all so set goal to one job and finish it then move on.

Thought about this a bit and its a fairly simple electronics circuit.
What you need is a bistable oscillator which can be made from a 555 chip and there are plenty of diagrams on line. In one position, say its flip, it switches the power source to a 15v regulator, if the power drops below the threshhold of the oscillator and it flops, the power is coupled directly to the load.
Now that is the simple explanation, you would have to use power transistors to feed the load and perhaps blocking diodes, Bistable perhaps a schmitt trigger, and use a lower voltage regulator so you can jack up its ground pin. But all up its easy electronics

Thanks rrobor,
I'll search what i can on your idea. I am a little lost with electronics so what comes easy to you guys results in hours/days of researching and palying around. At least it provides me with something to search on.