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Home Made Circuits

• Battery Level Indicator.
  
• Optical Obstacle Switch.

Related Circuits

• Telephone LED status indicator
• Music Sound to light converter
• Simple Water operated relay
• LED Voltage Level Indicator

These are circuits that you can build at home, which may help solve some small problems by building simple gadgets. That also will help you learn and improve your skills and knowledge.

Build Holiday Electronics Projects

555 is the most Important Hobby chip for hobby - 555 Timer based Circuits. In the Early Days, just like  "Ham Radio" the 555 brought in many Hobbyists into the Electronics DIY Arena. More than the Industry could Handle.   

It is important to learn analog and power electronics and then work on digital and Microcontroller. Then you will be able to interface the chip to the real world in a realistic manner and write frugal and lean code.



GainClone Chipamp Audio Amplifier

There are some things that should not be done by code, and some things which if done with code can save a lot of chips and cost.  So to be pragmatic in your approach, you should learn at home even as a student, on how to solve problems by building simple equipment.    

Perpetual Candle Project

This is a easy to build LED lamp circuit for Learning and building skills. This is the first draft schematic V 1.0. It will need improvements for Higher Power Lighting. Perpetual Candle Project

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.



FET Current Source and MOSFET

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.

One Single High Current LED may work well. 12 Matched LEDs also can be used. In LED Array some are dim, put min. resistor (3.9 ohm) for all 12 for current sharing. The resistor addition will impar the ability of Candle to work at lower battery voltages. Also resistor is less green, It wastes power, so use PWM and Single Die high current LED.

Ni-Cd system may last over 5 Years if Candle is allways on Mains. Sealed Lead Acid system may go upto 2-3 years life but will have more punch. A SuperCap system may last more than 12 Years, i feel. Source in Cadsoft Eagle format - candle.zip