Re: Constant current LED dimming



A great source for inductors (low value though) is old computer power supplies. They are not great, but for some applications they are ok. If you just need low current (150-200mA) you can use the ballast from the CFL lights (2-4mH).




Switching frequency is related with the required inductance. Minimum is usually 20kHz, to avoid audible noise in inductors. The high value is usually limited by switching losses (whenever transistors switch). It really depends on the application.

Some...

Re: Using an SMPS to charge a car battery



You could use an ACS712 module. Not that expensive, low insertion impedance, isolated (no need to bother about level shifters, common mode...) when I did my mod it wasn't available, today I would use it for sure....

Re: Using an SMPS to charge a car battery

Some years ago I modified an old AT power supply to charge a car battery @ 5A.
Modifications done: I put a current limit similar to eccerr0r's suggested schematic, with 0.1Ohm shunt resistor 5W
I moved the voltage sensing point to after that shunt resistor, and set it with a trimpot to 14.3V (bulk charge)
I added an small board that would set the voltage to 13.8V when the current decreases under a certain value (~0.4A if I recall good). It was made with the shunt, an operational amplifier (LM358) and a LM311 which changes...

Re: AT PSU mod - take two!

Very interesting topic!!!

Regarding current limiting, it is typical to use either the spare amplifier on the TL494 or the DTC pin (4). You can always add a primary current limit with a current transformer. The not-so-crappy AT PSU have one. They usually are configured as latching, to DTC pin.

For sensing I have been looking at the ACS712 modules. Affordable ($3.20), isolated and very low resistance (it can even be ignored) makes it a pretty interesting candidate