xaccto
Full Member level 5
34063 mosfet
what I got is a MC34063 controlled switcher, switching a mosfet
the coil is 8T 1mm wire, output Voltage is 13.75V
That circuit works pretty good, nice efficient too, no trouble supplying 1A load.
its switching freq at that load ~73khz
Only trouble is if you short the output, the diode is smoked!
So since there is plenty of room to wind a secondary coil, I put on 26T of 0.5mm wire,
changed the diode to the secondary, and moved the f/b resistor to there.
The best now I get with 1A load is 5.8V, the frequency of the switcher is now at 33khz. efficiency is very poor, maybe 50% if that.
I am having trouble understanding this? anyone got some comments?
why is the controller switching freq so low ? it doesn't seem to be attempting to regulate the output....... but the no load output is 13.5V...
I'm guessing winding on the secondary coil effects the inductance of the primary coil, but but, anyway is is supposed to be this hard to design switching transformers?
Thanks
what I got is a MC34063 controlled switcher, switching a mosfet
the coil is 8T 1mm wire, output Voltage is 13.75V
That circuit works pretty good, nice efficient too, no trouble supplying 1A load.
its switching freq at that load ~73khz
Only trouble is if you short the output, the diode is smoked!
So since there is plenty of room to wind a secondary coil, I put on 26T of 0.5mm wire,
changed the diode to the secondary, and moved the f/b resistor to there.
The best now I get with 1A load is 5.8V, the frequency of the switcher is now at 33khz. efficiency is very poor, maybe 50% if that.
I am having trouble understanding this? anyone got some comments?
why is the controller switching freq so low ? it doesn't seem to be attempting to regulate the output....... but the no load output is 13.5V...
I'm guessing winding on the secondary coil effects the inductance of the primary coil, but but, anyway is is supposed to be this hard to design switching transformers?
Thanks