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Tuesday, March 15, 2011

Solar Charger Using 555 : Simplest Approach to Battery Charging

We came across an innovative Solar Charge based on 555 developed by Michael Davis. The best part of the design is that its so cost constrained/ Low Cost that any one in any place in the world can build this crcuit, especially developing countries like Bharat(India).
Source: mdpub.com
The site gives complete details of how the Circuit works and also what are the components used to build it. Here is a list of the Bill of Materials for this project:
IC1 - 7805 5 Volt positive Voltage Regulator    
IC2 - NE555 Timer Chip    

Q1 - 2N2222 Or Similar NPN Transistor
Q2 - IRF540 Or Similar Power MOSFET

R3, R4, R5 - 1K Ohm 1/8 Watt 10%
R6 - 330 Ohm 1/8 Watt 10%
R7 - 100 Ohm 1/8 Watt 10%

R1, R2 - 10K Multi-Turn Trim-Pots

PB1, PB2 - NO Momentary Contact Push Buttons       

LED1 - Green LED    
LED2 - Yellow LED    

RLY1 - 40 Amp SPDT Automotive Relay    

C1 - 0.33uF 35V 10%
C2 - 0.1uF 35V 10%

D1 - 1N4001 or similar    
This would roughly cost around INR200 in Bharat(India). The next components needed are the Battery which might be slightly costly INR1000-4000 depending on the brand and the Capacity. Also the Solar Panels are are locally available in Bharat(India) at a cost of INR600-1500 range depending on the capacity requirements. The calculations for the Battery and the solar panel needed to processed to get the perfect charging time. There is good explanation on Michael's Website.
Here is the Schematics:
Source: mdpub.com
The Circuit is simple enough to be build on the vero-board and enclose in the same manner as shownin Michael's Website.
Source: http://www.mdpub.com/555Controller/index.html
There is a nice video showing this innovation at work:

For More Information Visit the Website:

We congratulate Michael Davis on his simple and Innovative Creation !!


  1. may you explain the theory of the circuit?

  2. Hello,

    You can get the best description from Michael Davis.
    He has done a wonderful job explaining this circuit.

    Warm Regards,