cybercheater
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if transformer is generating 150V. there may be a doubler circuit at output.
Try to search doubler circuit. if anyone knows plz reply.
for a flyback transformer (SMPS ) you have to calculate the dutycyle also
The SMPS UC4845 oscillator has two inputs:
* Voltage feedback is used to reach the desired voltage, when voltage in capacitor divided in the potentiometer reachs the reference voltage, the oscillator stops.
* Current sense input is normally used to control the maximum current in the mosfet. It depends on transformer inductance and oscillator frequency, but not on load (with this topology).
Here, this input is used to control the temporary switching-off the power supply while the PIC activates the SCR to discharge capacitor. When line is 0 volt, the oscillator is ON, when line is higher than 1 volt, oscillator stops. This is done for two reasons:
It means that the pulse areas V*t during on-state and flyback-state must be equal. If you put in the voltages and winding ratio, you get the time ratio respectively duty cycle in continuous mode.what do you mean about balancing the transformer flux?
it is possible to operate in discontinuous mode if i used EFD20 core with air gap? what a value of current sense resistor i should use?
Capacitor discharge ignition - Wikipedia, the free encyclopediaI dont know what is CDI
It's not completely clear to me, which point of the discussion you're referring to. It's a trivial fact, that the output voltage can reach any value (after sufficient time). The problem with CDI is, that the nominal output voltage has to be achieved in time (before the next ignition pulse) without causing unacceptable inductor peak currents. The circuit dimensioning should consider this requirements.In flyback converter if you not connect the te load voltage will keep increase in every pulse depends on your output cap.
No matter what is the turns ratio, duty cycle etc.
Possibly to limit an overshoot of the discharge oscillation, that may retrigger the thyristor.why second diode is required?
It's actually done in the described system by the control input. Nevertheless, the thyristor will be most likely switched off during the oscillation of the LC circuit formed by capacitor and ignition coil. And the converter is only supplying current pulses.It would seem you need to gate the boost switcher.
It's on the lower end of usual voltage range.300v seems low to me for CDI.
Yes. As pointed out before, operating the UC38xx controller in it's intended current mode would completely solve this issue.You need to have a primary circuit that limits the maximum duty cycle of the MOSFET driver or it may saturate the core and damage the MOSFET.
This DC-DC converter charges a 1uF capacitor at 250 volt in aprox. 1 msec. This theorically lets the CDI spark near 1000 times per second, 60,000 rpm in a single cylinder engine (1 spark per rev), 30,000 rpm rpm in a 4 cylinder engine (1 spark each 2 revs per cylinder).
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