Trying to improve on the transformer efficiency, I changed the configuration of the rectifier from half wave to full-wave. Below shows the configurations I used
Transformer turn ratio is enough so that the input side on the LDO is maintained well above drop-voltage + output voltage. The load on the LDO consumes about 130mA.
I was expecting twice the efficiency improvement, but the result is not what I expected. With secondary side current consumption remaining the same, I only saw 10mA improvements on the primary side.
With half wave rectification, the primary was consuming 110mA, and with full wave rectification, the primary was consuming about 100mA.
The transformer is very hot, and the hotter it gets, the current consumption grows more on the primary side.
Is there anything I am missing?
I add the component value as following
The single diode is MRA4007, which has about 0.7V forward voltage The bridge diode is MB6S which has 1V voltage drop per bridge.
Transistor is simple PZT2222 which is simple BJT.
The pulse I am using is 18V when high, and 0 V when low.
The frequency driving is about 31KHz. I changed the frequency to 45KHz, but the current
consumption rather increased. I think there is some kind of loss when switching.
The resistor value, I tried using 3.3K to 10K Ohm, but i saw little improvements.
The capacitors are 10uF plus 0.1uF in parallel before the LDO.
I will try to measure inductance of the transformer and let you know