Attached here is a useful reference for use when designing SMPS transformers.
If the output is not regulated then do not mess with the feedback circuit.yet still im only doing +-70 volts DC output at max.
That core is for a wound transformer, NOT an inductor. Frequency is determined by the components on the PWM clock.maybe judging by this ferrite index we can approximately know how many turns would be required for a given frequency
Yes, that's step two or three for me. Before getting anywhere close to the mains voltage, I'll run the primary off of a low voltage AC bench supply and the control circuitry off a bench DC supply, with the feedback loop jiggered accordingly. Later with with the mains isolation transformer in place, first use a well below design rating fuse, and so on. Little by little.You must be careful testing that circuit. I use a 1:1 mains isolation transformer and earth the common reference when working inside live switching power supplies.
Are you suggesting that those in the East are not, or the West should not be extremely concerned about safety?I see that in the west you are extremely concerned about safety ,
I am not going to answer your endless streaming thoughts on modifications to a tested SMPS design if you are not prepared to focus on the real issues. So long as you avoid those critical issues, you are lost. You are reacting emotionally to the circuit. I expect you will mess it up even more by going off on further “reality avoidance tangents”.personally i think i would be better of reducing the duty cycle length and increasing frequency , as to give the transistors more deadtime , since the core saturates probably quite fast anyways so the longer duty cycle is useless beyind saturation yet the higher frequency could push more useful power through the core.
I asked the question because, if you use the scope probe ground on one side of that inline test resistor on the primary, without an isolation transformer, you may well short the high voltage primary to earth ground through the scope. That won't go well for the scope lead or your primary circuit.so that i can attach an oscilloscope and see the waveform
In practice, the flux density change, ΔB, is
limited either by core saturation or by core loss,
thereby limiting the volt-seconds per turn that
can be applied to a specific core cross-section
area. To fully utilize any core, the design should
result in ΔB close to the saturation or core loss
limit, whichever governs, by adjusting either the
core area, the number of primary turns, or the
The flux density in the core (which links both
windings) is determined solely by volt
seconds per turn applied to the primary
(Faraday’s Law), independent of load
The Coroners verdict will be that "the deliberate use of an oscilloscope with a live common chassis" was tantamount to the murder of those who responded to your suicide. I need not say more.ok mheslep, I see your point ,. but the scopes my friend has have no grounding at all in the socket , nor are they otherwise grounded, nor the scope chassis has any ground connection, . most of our sockets don't have any grounding , just the phase and the neutral , even those who have the separate ground connection are useless because the older cables had only two wires in most home AC installations.
NO. Live controls are dangerous to you and the circuit. You can adjust it to the point where it destroys itself while you are trying to optimise output. It is one thing creeping up on an optimum operating point, but you must also be able to get there and back safely when applying, removing or momentarily interrupting power to the circuit at any time. In aerodynamics that region of operation is called "coffin corner".so this is basically saying the same thing i said earlier about having a reostat to control the duty cycle manually, or to see whether the feedback is working ,
Ok, the above comment to me shows this thread is on the verge of needing to be shut down. There is no place in the primary circuit you can put a series resistor and have one side of it already grounded simply due to the nature of the design of the circuit. Sticking a scope probe ground on either side of a series resistor in the primary circuit guarantees disaster. One way to 'see' the voltage across a resistor of this sort using a scope is to have a 2 channel scope that you can invert one channel and use the summing function of the scope. The difference in voltage from one side of the resistor to the other will then show up in the scope display.Also nothing bad can happen to the scope otherwise because the voltage will be only that which is dropped across the resistor hence very small.
If you have to reduce the line voltage to the point that the 5 volt regulator goes out of regulation then use a battery ahead of the 5 volt regulator until you have the problem solved.