I have been experimenting with DC-DC boost converter design. After I made some calculations in order to obtain a certain output based on certain parameters, I tested the SMPS and saw that it's not working as I designed it to.
D=0.629 or 62.9%
The batteries are rechargeable (2 X 1.2V) NiMH 800 mAh. I checked them after I used the converter last time and they were almost fully charged (2.3V). The PWM part (the 555 and resistors + capacitor) are powered by a 9V battery.
By checking the boost converter with a multimeter, I found that the output was 20V and 80mA, which is far from what I wanted. I noticed that once I connect the probes it takes some time (but it's still short) before the output reaches 20V.
It sounds like I traded voltage for current without knowing. The diode I used is not great, but I would not consider it to be the cause. According to the second site, output current is influenced by IC current and this can be a possible cause, but I'm not sure of it. Reducing the value of the inductor doesn't seem to help in increasing the current.
What do I have to change in my circuit, in order to get the desired results? How do I increase output current?