Hi everyone,

I'm building a power supply similar to the one from Carlos.

It has some snubber capacitors/resistors with std. values.

Just 4 fun, I thought I would try to optimize those values for the parts I have chosen.

I read an article here somewhere about snubbers and how to det. values for them. The article said that since the ringing of an AC/DC psu occurs when the diodes are tuning off and that this is due to the leakage inductance + stray capacitance of the transformer/diodes.

Therefore, has to det. the leakage inductance and stray capacitance and then plug those into some equations to calc them.

For example:

-snubber resistor, SR = sqrt(L/C), where L is the leakage inductance and C the stray or interwinding capacitance

-snubber capacitor, SC = 2 * Pie * sqrt(L*C) / R.

So, the first question is:

1. how to measure the leakage inductance of a transformer.

2. Do i simply short the secondaries with a good thick wire and measure the inductance of the primary, is that it?

3. Or do i need to det. all the resistances, e.g. of the short wire, my DMM when shorted, dc resistance of primaries, secondaries, turn ratio's, reflected resistance, etc.?

Sorry but I'm a little confused about how to go about this... I'm just hobbyist, so a super expensive LCR meter isn't an option for me. However I do have an oscilloscope and a function generator at my disposal.

Thanx,

Chris

I'm building a power supply similar to the one from Carlos.

It has some snubber capacitors/resistors with std. values.

Just 4 fun, I thought I would try to optimize those values for the parts I have chosen.

I read an article here somewhere about snubbers and how to det. values for them. The article said that since the ringing of an AC/DC psu occurs when the diodes are tuning off and that this is due to the leakage inductance + stray capacitance of the transformer/diodes.

Therefore, has to det. the leakage inductance and stray capacitance and then plug those into some equations to calc them.

For example:

-snubber resistor, SR = sqrt(L/C), where L is the leakage inductance and C the stray or interwinding capacitance

-snubber capacitor, SC = 2 * Pie * sqrt(L*C) / R.

So, the first question is:

1. how to measure the leakage inductance of a transformer.

2. Do i simply short the secondaries with a good thick wire and measure the inductance of the primary, is that it?

3. Or do i need to det. all the resistances, e.g. of the short wire, my DMM when shorted, dc resistance of primaries, secondaries, turn ratio's, reflected resistance, etc.?

Sorry but I'm a little confused about how to go about this... I'm just hobbyist, so a super expensive LCR meter isn't an option for me. However I do have an oscilloscope and a function generator at my disposal.

Thanx,

Chris

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