Kapanadze Cousin - DALLY FREE ENERGY

[Void]

Ok, I soldered in my ERZ-V10D151 varistors from Drain to Source on each MOSFET
and retested with V+ at 12V and again at 24V, and it is seems to be working acceptably.
With the 10uF cap disconnected from V+ now, I get no heating on the UF4007 diodes even at V+ = 24V.
The MOSFETS stay completely cool to the touch as well at 24V.

The only components that are getting hot at 24 V are the 220 Ohm 2 Watt resistors I am using
in the series RC snubbers, so I will eventually change those out with 5 Watt ceramic block resistors
and I should be able to run steady at 24V without the resistors overheating.

The non-dissipative snubbers are working OK using the UF4007 diodes with no electrolytic
connected to the yoke center tap, so I think I will stick with this for now unless I run
into new problems later on when I am doing my experimenting with different setups.
So there you go. The component values I am using may not be optimal, but they are at
least keeping the switching spikes below 200V, so not so bad I guess.

Itsu, I notice the current limiting light on my bench power supply is flickering on when I
use it to power the PWM driver board, so that probably accounts to some extent for the drooping
waveforms you mentioned. Something odd is that when I put even just a 100uH choke in the
power supply V+ line, it chokes out the rectangular waves on the toroid primary. I just get
big switching spikes but the rectangular waveforms are all degraded. What choke value
are you using in your power supply V+ line, if you are using one?

All the best...

[itsu]

Void,

thanks for this info, i wonder why this 10uF cap has such an impact, it should only more filter the 12/24V supply voltage.

I have build a small pcb with a non dissipative snubber consisting of 1mH inductors, 0.1uF caps and UF4007 diodes.
I will be testing tonight.   
I have some BAT46 schottky diodes  (100V), but i doubt they can handle the abuse like you mention. 
Else some D12G60C schottky diodes (12A / 600V) are available too.

The last weeks i was using batteries for both 12V and 24V supply voltages, so without any filter chokes or caps.
Since the last video i use a 24V (and 12V) cheap led PS with added common mode choke (7mH) and filter caps (900uF elco, 230nF poly and 0.1uF ceramic) on its output.

For protection i have a 6A fast fuse in the 24V line to the yoke.

Itsu

[MenofFather]

How I known and understand, shottky diodes have wery small input capasistance, so they not works like capasitors, UF diodes or other, works like capasitors partialy. Expeshaly low voltage shottky diodes are wery fast, much faster (maybe 10 or 100 times), than UF and SF diodes and other silicon diodes and almost not have capassitance. So maybe this peaks in Void oscilograms is from slow UF diodes, whose works like capassitors? And to reduce peak voltage on snubbers, maybe need use bigger capasistance capasitor in not dissipation snuber?

[AlienGrey]

Hi all yes  there are many snubber circuits to be honest I have my circuit working just fine, so I wont be using your RC circuit as it is still in the development stages, years ago my mouther bought a Hover 'dust-et' vacuum cleaner It was impossible to have the radio or TV on when it was running, it had an RC suppressor I had to put some VDR device across the C to shut the dam thing up  .

In your circuit some thing is not right you don't have a any way to drain the capacitor as it will just charge up until the MosFet conducts and drains the capacitor adding excess current to the conducting MosFets load, you would need  a fast diode to stop the back EMF getting back to the MosFet  going from 12 volts to 24 Volts will only add to your problems, my point is this type of circuit is fine in a vacuum cleaner as it has no voltage sensitive components. Your circuit experimental and I can't tell from the paperwork if the diodes are Schottky or fast Zener family or if the circuit works but it has no way to remove HV spikes, and the value of C is charge against time (frequency) is your F constant ? Will it under cut or over pass and is it the correct circuit for your application ? of course you could ask TK for a second opinion, but anyway good luck lads. I'm more than happy if you can prove me wrong 

AG

[Void]

Void,
thanks for this info, i wonder why this 10uF cap has such an impact, it should only more filter the 12/24V supply voltage.
I have build a small pcb with a non dissipative snubber consisting of 1mH inductors, 0.1uF caps and UF4007 diodes.
I will be testing tonight.   
I have some BAT46 schottky diodes  (100V), but i doubt they can handle the abuse like you mention. 
Else some D12G60C schottky diodes (12A / 600V) are available too.

The last weeks i was using batteries for both 12V and 24V supply voltages, so without any filter chokes or caps.
Since the last video i use a 24V (and 12V) cheap led PS with added common mode choke (7mH) and filter caps (900uF elco, 230nF poly and 0.1uF ceramic) on its output.
For protection i have a 6A fast fuse in the 24V line to the yoke.
Itsu

Hi Itsu. It will be interesting to see how your non-dissipative snubber compares
to my setup. I also still don't understand why my adding the 10uF cap at the toroid primary
center tap causes some of the UF4007 diodes to get hot. I should test with that further as I was
getting better switching spike reduction with the 10uF connected.

I find it very odd that when I place a 100uH choke in my power supply V+ line
that it degrades the rectangular waveforms quite a lot. I need to investigate this further
as well to see if I can figure out what the problem is there.

How I known and understand, shottky diodes have wery small input capasistance, so they not works like capasitors, UF diodes or other, works like capasitors partialy. Expeshaly low voltage shottky diodes are wery fast, much faster (maybe 10 or 100 times), than UF and SF diodes and other silicon diodes and almost not have capassitance. So maybe this peaks in Void oscilograms is from slow UF diodes, whose works like capassitors? And to reduce peak voltage on snubbers, maybe need use bigger capasistance capasitor in not dissipation snuber?

Hi Menof. You may well be right that using Schottky diodes could give a lot
better results. It is worth trying to compare the results. I would have to order some,
as the Schottky diodes I have on hand only have a reverse voltage rating of 100V and 60V.
Yes, changing the C value might give better results as well.

All the best...