Post by thread:[EE] switching power supplies

Hello everyone, I'm designing two switching supplies and I need your help. First is an 1,5 A, 0-45 V supply for an electromagnetic brake with 100-250 V input. I did simulations and everything seems fine with a MOSFET switching directly into the coils which provides enough inductance and resistance to filter the output with a 100nF parallel capacitor. I'm looking into 100 kHz PWM input to the MOSFET and there won't be any actual voltage regulation, I shall use a PIC running a PID loop on feedback from a load cell to maintain desired torque varying the current flow. I have a couple questions though for the more experienced people: should I filter the input voltage or is the raw rectified input OK? How would you drive the MOSFET from the PIC? Also, I used an IRF730 for simulations, would anyone say it's not a good choice (or have a better recommendation)? Second is an 8 V (fixed), 15 A supply for a bunch of big 7 segment displays. Due to the high current I'm also looking into a transformerless supply (100-250V input). Does anyone know of a regulator that will do the job? There are endless parts on newark and digikey and I could spend eternity to find one... Thanks in advance. Cristovao.

On 3/15/07, Cristóvão Dalla Costa <spam_OUTcdallacostaTakeThisOuTgmail.com> wrote: > Second is an 8 V (fixed), 15 A supply for a bunch of big 7 segment displays. > Due to the high current I'm also looking into a transformerless supply > (100-250V input). Does anyone know of a regulator that will do the job? I have used standard PC power supply (less expensive) . It's quite easy to modify the +12V supply to +8V (if you have some experience). But I think it's much better to split the 15A supply in three or four smaller modules, this will help you a lot with cable routing. Vasile

On 3/15/07, Vasile Surducan <.....piclist9KILLspam@spam@gmail.com> wrote: > > On 3/15/07, Cristóvão Dalla Costa <cdallacostaKILLspamgmail.com> wrote: > > > Second is an 8 V (fixed), 15 A supply for a bunch of big 7 segment > displays. > > Due to the high current I'm also looking into a transformerless supply > > (100-250V input). Does anyone know of a regulator that will do the job? > > I have used standard PC power supply (less expensive) . It's quite > easy to modify the +12V supply to +8V (if you have some experience). > But I think it's much better to split the 15A supply in three or four > smaller modules, this will help you a lot with cable routing. > > Vasile Thanks, but these will be manufactured in quantities of 50 or so initialy, I'm not sure that would be a feasible option.