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Old 09-04-2007, 11:39 PM
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Aaron Aaron is offline
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pulse doubler

In the skype chat, furvertme said:

""unipolar" "pulse frequency double" The inductor does not produce a second pulse, it continues the first one's current. Though measuring V at the inductor would resemble another pulse, the V at the WFC does not pulse, it just continues to charge for a short time."

This may be true. When I was looking at the scope when I did the bifilar test, I saw higher voltage but at the same frequency. I did not see twice as many pulses for the same time period. POSSIBLY, this might be correct.

But with Meyer's pulse diagrams..he shows the square going in at 50/50 duty cycle and the output are triangular pulses 1 for each on pulse and 1 for each off indicating double pulse.

So we need to figure this one out for sure.

He/she also says:

"[1:47:06 PM] furvertme says: series inductor switching power supplies can produce very high voltages since they use the back emf or flyback voltage to perform the boost. It does not limit to 2 times supply. The 2 times supply is a simple rule for cap charging circuits that are not pulse driven just load dump and recharge. In those the inductor peaks the charging current and continue to charge beyond the supply until it drains flux back to zero at about double supply. This is only true if the supply is stable DC during the entire charging.
[1:49:58 PM] furvertme says: AaronsDesign4.pdf or 5 files show a simple way to convert a Lawton circuit to operate as a boost switcher
[1:51:35 PM] furvertme says: Ipk = 2 x Iout,max x (Vout / Vin,min)
Tdon = (L x Ipk) / (Vout - Vin)

Output voltage is regulated by controlling the duty cycle.
Vout = ((Ton / Tdon) + 1) x Vin

Ripple voltage is directly proportional to diode conduction time.
Tdon max = (L x Ipk) / (Vout - Vin,max)

[1:52:36 PM] furvertme says: version 5 added a second diode and a cap between the output and the WFC to better control the power results.

[1:53:41 PM] furvertme says: Warning: This can produce HV with some serious currents and thus can be dangerous to people"

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The red part I highlighted indicates a misunderstanding that the collapsing magnetic field is NOT back emf.

When you ACTIVELY apply power to a coil, you get back EMF DURING the application of power. It is coming back countering the applied field AT THE SAME TIME.

The collapsed magnetic field that is time compressed to boost voltage is an event that happens AFTER the power to the coil is shut off.

The "flyback voltage" or collapsed magnetic field has nothing to do with back emf. They are NOT the same thing.
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