Hello friends,
Just playing with some 18V/4A DC-DC with TL494 and works nice (read stable
from now on). Topology is boost, single MOSFET and I just added a secondary coil coupled with main inductor so I guess it became some flyback design. These because I needed to lower output under 12V for other future use and also some isolation. So now input is 12V and output adjustable 6...20V at several amps.
Ok, most trouble was of course main inductor and I choose for testing several ready made chokes from PC SMPS or other PSU, measured in range of 20...150uH. Almost all worked nice (tuned each from controller PWM freq.) but when I made my own inductor for bigger current, all kind of audible sounds came from it. Also scope mounted in MOSFET grid shown ugly jitter on PWM.
Curiosity is the core was from the same junk SMPS, no mater I glued the winding, etc. I used some isolated cooper wire from a 60Hz trafo. When I made inductor with wire recovered from SMPS chokes, much improvement was observed.
So does the wire (quality) count so much ??? Or what's happening?
Best regards,
Ed
Just playing with some 18V/4A DC-DC with TL494 and works nice (read stable
from now on). Topology is boost, single MOSFET and I just added a secondary coil coupled with main inductor so I guess it became some flyback design. These because I needed to lower output under 12V for other future use and also some isolation. So now input is 12V and output adjustable 6...20V at several amps.Ok, most trouble was of course main inductor and I choose for testing several ready made chokes from PC SMPS or other PSU, measured in range of 20...150uH. Almost all worked nice (tuned each from controller PWM freq.) but when I made my own inductor for bigger current, all kind of audible sounds came from it. Also scope mounted in MOSFET grid shown ugly jitter on PWM.
Curiosity is the core was from the same junk SMPS, no mater I glued the winding, etc. I used some isolated cooper wire from a 60Hz trafo. When I made inductor with wire recovered from SMPS chokes, much improvement was observed.
So does the wire (quality) count so much ??? Or what's happening?
Best regards,
Ed