Hi,
Actually I have asked for this problem before in Tube forum. However, I havent found a solution yet.
I have the circuit below. V1 and R3 represents the transformer (220V to 300V, 180VA) and its equivalent series resistance (Rp=11.4ohm, Rs=16.2ohm). C1 and R2 represents the electrolytic capacitor I am using. That is a new Kendeil 05 type. R2 is max ESR specified by manufacturer (170mOhm).
I have built the circuit and also simulating on Orcad. In real circuit I am measuring 395Vdc at (+) pin of C1 and ground when there is 297Vrms in secondary of transformer. 297*1.414=420V. The first question is why I am measuring 395V instead of 420V ? (DMM is a cheap one, not a true rms device)
The graphs below is from Orcad. It seems there is a ripple current of 11A at first. Kendeil 05 is rated at 1.8A. Is it harmful for it ?
Is ESR=170mOhm low compared to other capacitors (Nichicon NT etc.) ?
Can I easily measure ESR of a capacitor ?
Thanks so much in advance.
MB
Actually I have asked for this problem before in Tube forum. However, I havent found a solution yet.
I have the circuit below. V1 and R3 represents the transformer (220V to 300V, 180VA) and its equivalent series resistance (Rp=11.4ohm, Rs=16.2ohm). C1 and R2 represents the electrolytic capacitor I am using. That is a new Kendeil 05 type. R2 is max ESR specified by manufacturer (170mOhm).
I have built the circuit and also simulating on Orcad. In real circuit I am measuring 395Vdc at (+) pin of C1 and ground when there is 297Vrms in secondary of transformer. 297*1.414=420V. The first question is why I am measuring 395V instead of 420V ? (DMM is a cheap one, not a true rms device)
The graphs below is from Orcad. It seems there is a ripple current of 11A at first. Kendeil 05 is rated at 1.8A. Is it harmful for it ?
Is ESR=170mOhm low compared to other capacitors (Nichicon NT etc.) ?
Can I easily measure ESR of a capacitor ?
Thanks so much in advance.
MB
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The 1.414 multiple assumes no load at all on the supply, it's just the peak voltage of the AC in. You two diode drops in your bridge, and have a bleeder resistor of 220K. It only draws a small current, about 2ma, but it reduces the average voltage a tad. There is also very very slight leakage current through the diodes and the capacitor.
Do you know the accuracy spec of your DVM? If not, compare its reading to some well known reference voltage. It may also be misleading you.
Do you know the accuracy spec of your DVM? If not, compare its reading to some well known reference voltage. It may also be misleading you.
>The 1.414 multiple assumes no load at all on the supply, it's just
> the peak voltage of the AC in. You two diode drops in your
> bridge, and have a bleeder resistor of 220K. It only draws a
> small current, about 2ma, but it reduces the average voltage a
> tad. There is also very very slight leakage current through the
> diodes and the capacitor.
Is it possible to drop 30V in diodes, bleeder resistor, leakage currents ? It seems too high to me.
DC Voltage Accuracy is %0.5, AC Voltage Accuracy is %0.8
Thanks.
MB
> the peak voltage of the AC in. You two diode drops in your
> bridge, and have a bleeder resistor of 220K. It only draws a
> small current, about 2ma, but it reduces the average voltage a
> tad. There is also very very slight leakage current through the
> diodes and the capacitor.
Is it possible to drop 30V in diodes, bleeder resistor, leakage currents ? It seems too high to me.
DC Voltage Accuracy is %0.5, AC Voltage Accuracy is %0.8
Thanks.
MB
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