This project shows how to build a constant current source based on two LM317 ICs. The purpose was to power two sets of 28 LED’s tied in parallel from a 12V source. The PCB design is done on Eagle and the current is set to 20mA for each led so that is 560mA for each set of LED’s. Check the design on the link below.
LM317 constant current source - [Link]
This project shows how to build a simple but efficient PWM LED light dimmer circuit.
LEDs (light emitting diodes) are very sensitive components – exceed their rated current or voltage and their lifespan can be slashed from 50,000+ hours to a microsecond. LEDs are current-driven * which means that the intensity of the light they generate depends on the amount of electric current flowing them.
PWM LED Dimmer Circuit - [Link]
This circuit is a supply voltage monitor which uses a LED to show the status of a power supply.
This simple and slightly odd circuit can clearly show the level of the supply voltage (in a larger device): as long as the indicator has good 12 volts at its input, LED1 gives steady, uninterrupted (for the naked eye) yellow light. If the input voltage falls below 11 V, LED1 will start to blink and the blinking will just get slower and slower if the voltage drops further – giving very clear and intuitive representation of the supply’s status. The blinking will stop and LED1 will finally go out at a little below 9 volts.
Supply Voltage Indicator – [Link]
This is a 9V power supply which will work even on power failure. It uses a rechargeable battery and regulators. A transformer with 15-0-15 AC volts output is required.
Battery Backup Supply – [Link]
This project shows how to build a wind generator using common materials.
Wind power is abundant, clean, inexpensive and easy to do. It is our belief that anyone can be in control of where his or her electricity comes from. There is nothing more rewarding and empowering than making a wind powered generator from scrap materials.
How to build a Wind Generator - [Link]
This project shows how to build a solid state relay based on opto-triac and triac. The opto-triac isolates the output from the input. With this solid state relay you are able to switch high current loads like with a normal relay. Another advantage of this relay is that it can switch loads fast. Check schematics on the link below.
Solid state relay - [Link]
Lithium Polymer Batteries are a very common source of power today. Many electronics gadgets have one inside, and they have some reasonable features. I’ve bought great batteries, with different sizes and capacities for my electronics projects. So long I’m using this batteries, coming the problem: charge them.
USB Single Cell LiPoly Charger - [Link]
Instructables user AaronX621 writes:
This will show you how to replace the internal battery on your Sonicare Elite 7300. After having my 2nd one die on me within 3 yrs I figured out how to rip it apart and fix it.
How-To: Replace your electric toothbrush battery – [Link]
LED’s are great display tools. Their prices have decreased to a point where they are replacing more conventional light sources. In one sense their characteristic need for low voltages is an advantage e.g compatibility with I.C drives, but this voltage requirement can also be a disadvantage. I wanted to light some LED’s in a simple sign application, nothing fancy, but I needed to decrease the utility line voltage to a LED-compatible value for this application.
A power source for simple LED projects - [Link]
This circuit controls resistive and inductive loads up to 2,500W. Its main functional device is an integrated phase control circuit – Siemens TLE3103. It contains its own power supply, a zero voltage crossing detector circuit and a logic driver. An additional feature is the low voltage input to enable/disable triac firing enabling/disabling the logic driver.
2500W Phase Control - [Link]