Posted: 8/3/2015 1:17:48 AM EDT
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Found this schematic and decided to try it. It's based on a 555 timer IC.
http://www.mdpub.com/555Controller/images/555ChargeController2.jpg Idle current is about 7 mA. Seems to work well enough on the breadboard. I may use a single N-channel MOSFET by itself on the solar panel negative leg or combination with a Bosch style relay like the original schematic. I know micro controller based charge controllers will always be better, but this is going to be interesting to try. Fun to change the original design and it's also cheap to build. Remember, Pin # 2 controls the cut-in voltage and Pin #6 controls the cut-out voltage. I'm now thinking about trying an LM556 timer IC. Same as the 555 except is a dual timer package. Maybe possible to share some of the circuitry and build a two stage charger with different switching elements. EDIT: Maybe this should have been posted in the Ham Radio section? |
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That sounds like a lot of fun. About a year ago when I was learning enough to figure out how to design and make a pcb for my 555 based electronic, motion predator decoy I ran across the following board maker who can slap you together 10 boards cheaply and quickly. You may already be aware of them, but I would have never dreamed I could get 10 boards for 10 bucks to my door.
http://imall.itead.cc/open-pcb/pcb-prototyping/im120418001.html Good luck. |
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Quoted:
Pin 3 on the 555 is capable of directly supplying or sinking 200 mA - So why are Q1 and Q2 needed? I measured the voltages on Pin 3 and Pin 7. They both toggled between about .07 V and 3.55 V. I guess Q1 inverts the output of Pin 3 and provides a higher Gate voltage for the MOSFET. Is Q1 and Q2 really necessary? Q1 inverts the output of Pin 3 and keeps the voltage on Pin 3 from exceeding the chips VCC voltage of 5 volts. I'm guessing Q1 makes the circuit more reliable. |