Flash wrote:You could scan (or take a high-res picture of) a schematic, then, if necessary, use mtPaint to crop the picture and/or reduce its resolution to the minimum that still shows all the details. I use mtPaint to do that all the time.
Editing I will start on the left to explain:
I1 and the big chain of diodes is my model of the panel
R8 = 0.01 Ohms assumed for wiring from panel
C9, L1 is an EMI filter you will want in the final design to keep it out of your radio etc.
C5 is a place to store up some charge
D2 protects the "LM7908" against a sudden short at the panel. They don't like sudden 0V or negative V at their inputs when the output side has voltage
Q3, Q4 is my fake LM7908 I didn't have a good model of a real one.
I expect to make this a real one. We may change to LM7812.
Remember what I said about "ground" not really being ground. The rest of the stuff runs between 17V and {17-8V}
R10,R11 and "knob" is how I model the manual adjust 10K pot
U3 look up LM741. They quit making it but opamps are well explained using that as an example. The real one will be an 8 pin DIP for ease of prototyping. This circuit is what adjusts the PWM to make it hold the panel at a given voltage.
More explanation if you ask
LT1011 AKA LM311 is a comparator. When "-" is above "+" it pulls its output down to ground. When "+" is higher it doesn't do that so the resistor R4,R4 can pull it up.
Q1 and Q2 provide the ability to move a lot of charge in and out of the gate of M1
R6. C8 are positive feedback so that when the LM311 moves its output up or down it tends to stay there for a while.
R7, C4 are negative feedback so "for a while" comes to an end after about 10uS
R3, R4, C3 as so that when the output of the LT1011 swings up, it doesn't slow down as it nears the positive voltage. This is a "bootstrap"
D1 is a "catch diode" for L3
M1 and D1 alternate as M1 switches on and off. The average voltage across an ideal inductor is always going to be zero. The other end of the inductor is at our output voltage.
R2 is my current sense for making the change from having a pot to automating the action.