throbscottle
Well-Known Member
Attached is the badly drawn schematic for my first attempt at a simple boost converter, using a dual nand gate oscillator and a transistor used as a voltage controlled resistor to control the duty/frequency. It's intended to drive a pretty constant, light load, with a zener to clamp the output voltage, but has kept within a couple of volts over the range of load shown, so I'm feeling quite pleased. The output can be adjusted by means of the feedback resistor.
The test run is at 9v since that's the only psu I have at the moment, with outputs tested at 13v, 17v and 20v
I have a couple of issues with this circuit I'd like some help with:
1) it's not very stable, and can go into a state where the oscillator runs with an approximately 50/50 duty cycle, and the output goes up quite high, to around 35v. Don't know how it's doing that.
2) I'd like to be able to create a feedback circuit with reference for greater stability - any pointers how to do this?
TIA
The test run is at 9v since that's the only psu I have at the moment, with outputs tested at 13v, 17v and 20v
I have a couple of issues with this circuit I'd like some help with:
1) it's not very stable, and can go into a state where the oscillator runs with an approximately 50/50 duty cycle, and the output goes up quite high, to around 35v. Don't know how it's doing that.
2) I'd like to be able to create a feedback circuit with reference for greater stability - any pointers how to do this?
TIA