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/diy/ - Do It Yourself

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File: 44 KB, 643x439, Switch-mode-power-supply-circuit-with-an-MC34063.png [View same] [iqdb] [saucenao] [google]
1033971 No.1033971 [Reply] [Original]

Hello. I made basic stepup from schematic picrel, and transistor eems not working, o-scope not showing switching, always is about same voltage as vcc 4V from li-ion. Im sure there is no shortcut, can anyone help? Did i fuged transistors with soldering?

>> No.1033972

>>1033971
Op here, i also changed Ct cap from 200p to1n, no result, but there is some 0,75V sawtooth on Ct cap.

>> No.1033976

>>1033971
Can you post a picture of actual circuit, also have you tried using a spare chip?

>> No.1033978
File: 223 KB, 739x654, Bez tytułu.jpg [View same] [iqdb] [saucenao] [google]
1033978

>>1033976
it would be difficult to change chip, it's on small board.

>> No.1033996

>>1033978
Your schematic specifies a 100uF input capacitor and you have some random ceramic chip.
Is that current sense resistor anywhere near the correct value? Is it even connected properly?
That voltage sense trimmer does not look like it's connected as specified. And since this is a switcher, it should be near the IC.
And even if you're sure there are no shorts, are you sure there are no open circuits?

>> No.1034015

>>1033976
It working. Im stupid enough to connect potentiometer in wrong way. Middle pot pin to pin 5 of MC34063.