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Xringer · 07-20-10, 08:57 AM

NATIONAL SEMICONDUCTOR | LM78S40CN/NOPB | LM78S40 Series MDIP-16 Pin Universal Switching Regulator Subsystem - Future Electronics

Yeah it still around for 76 cents.. And there are some good app-notes on the page too.

The more I look at those Pump drivers from 'Down Under', the more I like them.

The MiniMax http://www.voltscommissar.net/minimax/schemati.gif
needs no feed back, it just delivers the max wattage available.
The pulse action will kick in when the clouds roll in.

The pulse rate will depend on the rise time of the panels and the size of the input capacitor.

When the sun gets really dim, I think a photocell mod might be a neat way to get those last few watts delivered..

14:27 edit:
Really over-cast out right now. Less than 30w of power. 17volts coming in.
But, when I open the cut-off switch, the open voltage jumps right up to 78 volts.
I'll bet the PV could charge up some caps pretty fast, even in this light.
This looks like the perfect app for a comparator controlled MOSFET..

20:32 edit:
The max power voltage for these panels (as marked on the labels) is 17.4 volts.
Times 4 panels is 69.6v. If the 10 ohm load saw 69.6v, that's 6.96 amps
that's 484 watts. Which would make me very happy.

Typically, it's running low, about 62.6v.. Into 10 ohms, that's only about 392 watts of power.
Being 7 volts low, (and 92w short of the dream wattage of 484) might be curable with a Pump controller..

07-20-10, 08:57 AM	#16
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	NATIONAL SEMICONDUCTOR \| LM78S40CN/NOPB \| LM78S40 Series MDIP-16 Pin Universal Switching Regulator Subsystem - Future Electronics Yeah it still around for 76 cents.. And there are some good app-notes on the page too. The more I look at those Pump drivers from 'Down Under', the more I like them. The MiniMax http://www.voltscommissar.net/minimax/schemati.gif needs no feed back, it just delivers the max wattage available. The pulse action will kick in when the clouds roll in. The pulse rate will depend on the rise time of the panels and the size of the input capacitor. When the sun gets really dim, I think a photocell mod might be a neat way to get those last few watts delivered.. 14:27 edit: Really over-cast out right now. Less than 30w of power. 17volts coming in. But, when I open the cut-off switch, the open voltage jumps right up to 78 volts. I'll bet the PV could charge up some caps pretty fast, even in this light. This looks like the perfect app for a comparator controlled MOSFET.. 20:32 edit: The max power voltage for these panels (as marked on the labels) is 17.4 volts. Times 4 panels is 69.6v. If the 10 ohm load saw 69.6v, that's 6.96 amps that's 484 watts. Which would make me very happy. Typically, it's running low, about 62.6v.. Into 10 ohms, that's only about 392 watts of power. Being 7 volts low, (and 92w short of the dream wattage of 484) might be curable with a Pump controller.. Last edited by Xringer; 07-20-10 at 07:45 PM..