Guru
Joined: 13/10/2014
Location: AustraliaPosts: 1860
| Posted: 08:18am 12 Jan 2023 |
I have 2 Ferite core chokes, one very slightly smaller than the other. I put a 2.5mm air gap in one and tested the saturation, it appears to now reach 150A before the knee, however the inductance is obviously smaller, no haven't measured it yet.
In use, it caused the idle current to raise about 60mA, AC out is still good, but the choke output has a lot of HF noise. I unwound 2 turns from the first ferite choke and then put them in series, the choke output was now acceptable, not as good as before but this is a first test.
There was that slight kink in the leading slope of the AC out, I had also noticed previously some glitches near the HI side transition in or close to the dead zone, so I took opportunity to grab as few CRO pictures of the waveform zoomed into the choke output and choke input and this is what I found. The dead zone glitch / spike is the thing that makes the kinks that I see on the side of the sine wave.
I was concerned that the Digital capture was introducing some strange spikes. I have two CROs, one a straight digital, the other an Analogue with a digital memory, I can switch between analogue or digital with the press of a button on one CRO, both CROs and the Analogue display showed the glitch spike.
Choke input and output.
Slope of Sinewave and Choke drive zoomed in.
Choke IN and Out overlayed.
AC out overlayed.
Edited 2023-01-12 18:19 by KeepIS