I used this schematic to build a half bridge power supply, but I have some problems and need some help.
The first problem is feedback.
I think this feedback is not good because with this feedback the transformer produces a noisy sound like "tik-tik-tik"about twice every second and the voltage changes beetwen 40 to 45 in each rail.
I read some where that this feedback doesn't control the duty cycle and it just turns the PWM on or off but I need a feedback that controlx the output voltage by decreasing or increasing the duty cycle.
Without feedback there is no noisy sound and the SMPS works fine. When I connected a 300 watt load the voltage dropped about 20 volts.
Pleasehelp me to change the feedback.
What should I do?
I changed this schematic a little bit.
- My primary winding has 19 turns. The secondary is 8*2.
- I used an ETD 39 core.
- The target output voltage is 45*2.
- I changed the frequncy to 80 kHz.