12V high current linear power supply is very useful for HAM applications. I designed one based on s53mv schematic. The circuit is somehow odd because regulation transistors are in negative side of the current loop. Main reason for that is the collector or source of the transistors, which is connected to the housing of the transistor. To avoid isolation of the transistors from the heat sink it is better to have the housing, heatsink and the transistors connected to negative rail of the power supply. It is similar to the car, where negative pole is connected to the chassis.
Single cell lithium polymer battery cell is very handsome power source for many applications. Unfortunately it is quite dangerous when such battery cell is not properly protected and charged. I prepared simple 1S LiPo battery protection and Charger on two, single sided small PCB modules. I separated Protection from the charger when only protection is needed.
This is small module for AS1337. The shematic is simple and provides all required components to operate AS1337. The PCB is 18x15mm miniature module with all pins at one side (S
This was one of my first designs when I started designing power LED circuits. The DC/DC controller is ON-Semi NCP3065. It requires power inductor, schottky diode and some other passives. NCP3065 is PWM controller suitable for many topologies, including buck, boost or sepic. Circuit presented here is classical step down buck (click to enlarge):
I’ve got samples of interersting DC/DC converter from TI: TPS61040. Main application is to drive small white LEDs from a battery cell or two. Input voltage range is from 1,8V to 6V. Ideal for two AA or single Li-xx cell. Schematics is very simple. Only few external components are required: a coil, caps and schottky diode:
2S Battery pack is very useful. It can be used to supply 5V electronic circuit without DC/DC. With help of a simple boost a 2S battery can drive 3 power LED lamp with reasonable currents. Etc…
Let’s see what is required for reliable, safe lithium polymer batter pack with two serially connected cells (2S LiPo battery pack).
Obviouslly, at least two cells are needed. Unfortunately, LiPo cells are very dangerous if used over specified limits. Most dificult is maximum cell voltage during charge. If cells are aexposed to voltages above 4,2V they can burn, but not at the charging, this could happen at any time after charging. The absolute maximum charging voltage is 4.25V per cell. To avoid burning down the house and other troubles, a battery protection circuit board (PCB) is a must with LiPo cells.
