The Center piece is a bamboo tube. The bottom of this pipe is a brass part. A autotransformer dial is the big washer. The LED array is from a Failed China Lamp and The Enclosure is a 10 CD Box. The Top Byzantine Structure is a Pepper Cap from Africa and a Furniture Knob.
Perpetual Candle – White LED Lamp on Ni-Cd
Perpetual Candle – Emergency Light 1W using LEDs, Solar panel can be also integrated with a single diode at input of LM317T. If your Solar Panel Voltage is low then use a DC/DC Converter or Joule Thief.
Read Earlier Post – Perpandle Design
How It Works ?
I will give a short summary, The LM317 here configured for around 6.4V DC. The Q3 BC547 limits the current, you can select R3 to suit, make it 1/2W. The Ni-Cd battery pack 1.2 * 4 will not get Over-Current or Over-Voltage due to this circuit.
The IRF540 Mosfet or any other equivalent you have around, along with Q2 BC547 forms a current source for the parallel 12 LED array. Ultra-bright White LED at 20mA each or use a 1W ready LED Chip. R4/R6 can be selected for the Max LED current. The voltage of LED is around 3.1 and 20mA * 12 = 240mA is the max current. You can Tweak the design for even 5A or more but then you will need a DC/DC High frequency converter in place of LM317. The Current source also needs to switch to improve efficiency. A PWM on the mosfet gives brightness control. The entire solution (switching) can be found in many chips with semiconductor vendors today.
Also use Heatsinks for both devices, may not be required, test is out.
Here is a circuit archive that takes you up, from the bottom rungs of the EE Semiconductor Design Ladder. There are many Discrete Transistor Designs, NPN and PNP with R, L and C. Bipolar design and diodes is the first Knowledge to assimilate. Next is FET, MOSFET and Thyristor study. Then you climb the Amazing Analog Design Rungs !!
You have reached a landing now, where they sell popcorn and Ice Cream. There is Lemonade and Ginger Beer too. Recharge your batteries and pack a Knapsack with stuff, for a long Expedition.
The rungs of digital design are most challenging, RF and Wireless design and Power Electronics rungs are scaled fast. Then you get into Embedded Systems. Reached the end, not yet … We have Computing Too To Do!
4QD-TEC: Electronics Circuits Reference Archive
Battery Monitoring circuits, Circuit Theory and tutorials, Component types and values, Current sensing and control, Industrial Control circuits and suggestions, Measurement Circuits, Motor Control Circuits. Power Supply circuits, Pulse (Width and position) Modulation Circuits, Relay Driver Circuits, Staircase generators, Test Equipment circuits, Temperature Measurement, Timer Circuits, Ultrasonic Circuits, Voltage/Current controlled circuits.
Best of ‘In Practice’ on the web – Articles and resources of long-term interest, including switch-mode power supplies.
Amateur Radio Technical Notebook – GM3SEK
The Triode Board – PC board and Kit for Triode PA control and protection
The Tetrode Boards – PC boards and Kit for Tetrode PA control and protection.
Cost-effective Ferrite Chokes and Baluns
Tables, charts, quick reference cards, booklets and handbooks; are the most versatile tools of learning and putting the learning into applications. These should not have a lot of language or flowing text. These are – to the point, easy to remember, graphical, colorful (memory aid).
Electronic Tables and Charts
Just like a circuit diagram, flow chart or ladder logic can graphically interface with a human mind, Tables and Charts easily embed into ones memory.