Understanding electricity in the TPU.

[giantkiller]

A good rule of thumb is r.m.s.(root, mean, square) of 63% of the A.C. peak to peak to get the rippled D.C.

[MrMag]

A good rule of thumb is r.m.s.(root, mean, square) of 63% of the A.C. peak to peak to get the rippled D.C.

RMS voltage is .707 of the peak to peak voltage. Also, the power coming into your house is the already measured as RMS voltage. This is the reason that when you rectify it, the DC voltage is higher.

[teslaalset]

I know that when you have a DC voltage output, that the AC equivalent is always lower but I don't know what the formula is. You see, when SM plugged his bulbs into the wall socket to show them lighting off the house mains, he was getting 110-120 volts AC on those bulbs and the bulbs are supposed to light up to their maximum ability based on that mains power input. He then plugged them onto the OTPU that supplies 91.2 volts DC. So here are some of my questions

1) What does 91.2 volts DC equal in AC terms.

120 Volt mains means 120 V RMS.
So with a sinus shape voltage in mind, 120 V can be compared with 91.2 DC directly, so 91.2/120v equals 83.4 %.

2) If the answer to #1 is less AC then what is available from the mains supply, should the bulb light up less or more then when it was plugged into the mains supply versus when it was plugged onto the OTPU.

Answer is obviously: less when plugged into the TPU compared to mains (see the percentage above)

3) When the second  bulb was connected to the OTPU the voltage reading of 91.2 vdc did not even budge by a 0.01 vdc. As if the OTPU was impervious (or invisible) to the applied load. Is this normal?

If the internal resistance of the power source is very low, this is normal.

[wattsup]

Thanks guys.

So if I understand this correctly from both your posts, @GK says the DC voltage produced is 63% of the RMS AC available from the wall outlet and @MK says the 110-120 VAC in the home is already in RMS.

So relating this to the OTPU output of 91.2 VDC, this would equate to (91.2 x 0.63) = 57.456 VAC being applied to the bulbs by the OTPU. Is this correct?

And, if this is correct, can you then go back and look at the bulbs being lit by the OTPU compared to the bulbs being lit off the mains and say that the bulb brightness is consistent or not consistent with this reality.

Then explain how the voltage on the OTPU did not even budge by 0.01 volts when the first then the second bulb was connected. So how is this possible that the bulbs are brighter (in my opinion) or at best just as bright.

I am doing this exposure in small steps because I realize the ramifications are rather dumbfounding. I am just letting the facts speak for themselves, as we all should, when doing SM TPU demo investigations. When I do the final bulb comparison pictures, this reality will hopefully be more evident.

@teslaalset

Thanks for your reply. I am not sure about your answers for #1 but I think @GK answered it already. I agree also for #2. Then for #3 I am very perplexed and guys doing TPU experiments know already what it means to not even have a 0.01 volts fluctuation when connecting a first then a second bulb.

[teslaalset]

A good rule of thumb is r.m.s.(root, mean, square) of 63% of the A.C. peak to peak to get the rippled D.C.

@GK
Our replies just crossed each other.

My understanding:
120 V mains means 170V peak voltage (have a look at an oscilloscope picture of the mains voltage)
This means 120 V mains AC can be directly compared with 120V DC