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Assembly of the power stage.

A project log for Bench power supply

USB and manual control, and monitoring, 2 channel 5A 30V bench supply.

rue-mohrRue Mohr 11/24/2015 at 05:060 Comments

Nov 23:

I'v started assembling the PWM power converter. During which I realized that when I modified pwm genorator to run on 5V, it was in part to make it match the error amplifier output, that whole transistor stage on the end of the error amp isn't needed anymore. oops.

So far, the pwm genorator is working. With luck, over the next few days, I'll get the schmitt, phase splitter, and fet driver going.

Nov 24:

Dear diary...

I assembled the rest of the phase splitter circuit and found some interesting problems, this isn't supposed to happen cause I'v already tested these circuits.

A glitch pulse in the pwm comparitor caused the pulses in the toggle flip-flop to get all messed up, After a lot of probing I found that I needed to add a 22pf cap between two of the ramp genorator pins, I'm going to attribute this to making up for the breadboard capacitance I dont have anymore.

It was then followed by an interesting timing error in the division of the pwm. The T flipflop is supposed to redirect the pwm signal after its definitly finished a cycle, this switching is happening a bit early and breaking up the pwm cycle wrong. In the process of trying to correct this, the ramp oscillator stopped working.

Thats as far as I got, I'm going to sit back and see if I can make some changes to garuntee better operation., like clocking the T flipflop off the pwm itself.... thats a good one... better write that down...

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