The main PCB for the charger is a single sided, 1.6mm tick printed circuit board. The DC/DC converter is now integrated within the charger in order to allow the charge of high number cell packs. The people that charges only few batteries (12Vdc supplies sufficient) can not mount the components for the DC/DC converter saving the money of this part. The DC/DC converter part is a generic step-up converter, capable to deliver 7.5A and an output voltage of 24Vdc, starting from a 12Vdc supply. The main parts are the following:
- PWM controller UC3843 very cheap and easy to find
- Power inductor from Bourns, type 2306RC (27uH, 15A), Farnell 1167731
- The power diode is a schottky type,and a N-type mosfet can be generic: all the two components are in case TO-220
Universal Charger: [Link]
This circuit provides a constant amount of power to the LEDs and also provides a constant amount of light for a longer period of time. This circuit also allows the LEDs to run on almost any normal voltage above 4 volts. This means you can use multiple sources of power for the same light, a few AAA batteries, or even a car battery.
Constant Current Supply For LED’s: [Link]
Mobile infrared electronic transmitter
Sometimes you need a simple negative power supply. The best example is the contrast PSU for common small LCD device. Building -5V from a battery or a wallmart supply isn’t really easy. The author used the MAX 764/765/766 series to build the power supply. You can simply change the chip to provide the desired output.
Negative Power Supply (-5V / -12V / -15V): [Link]
This is a precision ±15V regulator designed on a single side PCB. The original project is based on EB-802 and belongs to zerosoft. The author took the original project and modified it by replacing some of the components with others that are easy-er to find on the market.
The board has a really nice symmetry design and fits nicely into a case. You could use the regulator to power a pre-amp or a headphone amplifier with great results.
+/- 15V Power Supply: [Link]
The author started building this project to replace the failed power supply in he’s Heath Warrior amplifier. By reverse engineering some Dell computer supplies, he soon had a rough schematic diagram sketched out. Here is a short description on how this power supplies work: When the supply operates on 120 Volts, half of a full wave bridge rectifier charges a pair of filter capacitors to + and - 150 Volts, respectively.
These voltages are alternately switched across the primary winding of the power supply transformer by a pair of transistors connected in a “totem pole” configuration (A half-bridge” circuit.) The secondary windings produce various voltages which are rectified, filtered and distributed to the loads in the computer. Samples of the +5 and +12 volt output are used for feedback to the voltage regulator circuitry.
After some building and thinkering, the project was finished. The power supply was tested, and was able to handle 1KW of power by lighting 10 x 100 w lightbulbs.
DIY Power Supply able to handle 1 KW of power: [Link] - [Via]
