11-25-2011, 06:37 PM
Gvel
Thanks, I will try that.
I have a couple of Y-rated 2.2nF caps and an X-cap of 0.47uF from one of my projects.
Actually, I could also try a CM choke (to get rid of common mode RF signal on the AC line), and use two X-caps, one before and one after the choke.
A GND wire is usually helpful when using Y-caps, but that was not provided - these radios used 2-prong plug with no 3rd GND wire.
What I also think is good - I have some NTC thermistors I used to protect my supplies from the inrush current upon plug-in, and although Power XFMR itself is a protection, and the tube diode provides for no in-rush for filtering caps, once you introduce an input cap of 0.25-1.0uF, you will see a spark on plug-in, so an NTC thermistor might do some good here.
PS. What the authors forgot to mention that in the very first picture (with 2 Y-caps to GND), where the chassis is not Grounded (and it is usually not), the chassis is actually under floating potential of about 60V (the caps form an AC divider).
Of course, the current is very weak, and not likely to shock you, but it will give you an unpleasant "pinch" if touched.
This "weak" current is actually enough to kill some devices connected to each other. For example these 2 Y-caps without the protective GND were (and still are, in the same India) responsible for RS232 interfaces burning in then desktop computers (and now laptop computers) in Eastern Europe, when connected to local properly grounded devices.
Thanks, I will try that.
I have a couple of Y-rated 2.2nF caps and an X-cap of 0.47uF from one of my projects.
Actually, I could also try a CM choke (to get rid of common mode RF signal on the AC line), and use two X-caps, one before and one after the choke.
A GND wire is usually helpful when using Y-caps, but that was not provided - these radios used 2-prong plug with no 3rd GND wire.
What I also think is good - I have some NTC thermistors I used to protect my supplies from the inrush current upon plug-in, and although Power XFMR itself is a protection, and the tube diode provides for no in-rush for filtering caps, once you introduce an input cap of 0.25-1.0uF, you will see a spark on plug-in, so an NTC thermistor might do some good here.
PS. What the authors forgot to mention that in the very first picture (with 2 Y-caps to GND), where the chassis is not Grounded (and it is usually not), the chassis is actually under floating potential of about 60V (the caps form an AC divider).
Of course, the current is very weak, and not likely to shock you, but it will give you an unpleasant "pinch" if touched.
This "weak" current is actually enough to kill some devices connected to each other. For example these 2 Y-caps without the protective GND were (and still are, in the same India) responsible for RS232 interfaces burning in then desktop computers (and now laptop computers) in Eastern Europe, when connected to local properly grounded devices.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
