On 15/06/14 17:23, Chris Stalin wrote:
1. I also added a 220uF cap near the coil. I noticed the voltage jump
about 3 volts. I have kept the 220uF cap near the IC. Does any one
recommend I keep the IC cap or remove it o adjust its value? When
removed the voltage drops about 1 volt. So clearly adding or removing
caps adjust the voltage - just not sure why. None of my caps are low ESR
yet.
From the circuit, it's probably providing an alternate source of
current for L1 which bypasses R3..R6. What you're seeing is the
capacitor charging while Q2 is off then discharging into L2 when Q2 is
on, supplementing the current coming from R3..R6.
The 34063 notices that there's less voltage going through the current
sense resistors (via Ipk Sense) and reacts by increasing the power
through Q2 by increasing the duty cycle. (if I remember correctly the
34063 is an "almost-PWM" controller).
2. When my system is not loaded and just idling I see about 182.5V on
the 180V line and 535V on the 540V line.
When I load down my 180V line with 5mA of resistance my voltage jumps
555V on the 540 line. 180V line stays the same. Can any one explain why
this is happening? I would assume a load on the system would make
voltage sag not drop.
You have a Cockroft-Walton divider comprised of C6, D2, D3, and the
other unnamed parts. What you're probably seeing is the divider
responding differently to a change in input frequency and/or voltage.
In short, The 34063 is regulating the 180V rail, but not the 540V rail.
If your feedback was coming from the 540V rail you'd expect to see the
180V rail jumping around while the 540V remains stable.
Are you loading down the 540V rail at all?
3. Are the cap values critical? I need to pick up a couple more caps as
I ran out of HV caps. I currently have 2.2uF caps x 2 and the rest are
4.7uF and 10uF 450V caps - Just for testing purposes only. ( cap values
from 1-2.2uF throughout the HV section is acceptable ? )
I'll let someone else field this one as I don't have an answer. Sorry! :(
Though ideally for a C-W multiplier all the capacitors and all the
diodes should be identical. If they're not, this might be why you're
seeing the voltage rise slightly.
Thanks,
--
Phil.
phil...@philpem.me.uk
http://www.philpem.me.uk/
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