I agree with you peak voltage can reach 1.414 times measured AC. I mentioned 150 volt caps as that was the rating used in AC/DC radios. Modern replacements are now marked 160 volts. This is considered working voltage. Peak voltage on caps will be higher.
In AC/DC radios tubes warm up slowly. Rectifier tubes also have a voltage drop. This will limit voltage seen on the first filter cap.
I do agree, it's better to use caps rated 200 volts but these aren't always available. Caps are smaller now so a person could use 450 volt caps for almost all radios.
Norm
:Norm, in one of your recent responses, you mentioned using new caps of at least 150 VDC in AA5 radios, AC-DC type. While it is true that most old radios used 150 V. caps, I always found this a bit skimpy. If you assume 120 V line, then the peak at the filter should be 120 x 1.414 or about 170 Volts. The old time caps were probably designed with some safety margin, and also tended to be physically much larger than today's electrolytics. True, the voltage will be somewhat less due to rectifier tube drop, but still close to 150V.
: My 30+ years with Westinghouse and Siliconix cause me to be more cautious. I would use 200 V. caps, just for peace of mind. What do you think?
:Rich
:Hi Rich
:
: I agree with you peak voltage can reach 1.414 times measured AC. I mentioned 150 volt caps as that was the rating used in AC/DC radios. Modern replacements are now marked 160 volts. This is considered working voltage. Peak voltage on caps will be higher.
:
: In AC/DC radios tubes warm up slowly. Rectifier tubes also have a voltage drop. This will limit voltage seen on the first filter cap.
:
: I do agree, it's better to use caps rated 200 volts but these aren't always available. Caps are smaller now so a person could use 450 volt caps for almost all radios.
:
:Norm
:
::Norm, in one of your recent responses, you mentioned using new caps of at least 150 VDC in AA5 radios, AC-DC type. While it is true that most old radios used 150 V. caps, I always found this a bit skimpy. If you assume 120 V line, then the peak at the filter should be 120 x 1.414 or about 170 Volts. The old time caps were probably designed with some safety margin, and also tended to be physically much larger than today's electrolytics. True, the voltage will be somewhat less due to rectifier tube drop, but still close to 150V.
:: My 30+ years with Westinghouse and Siliconix cause me to be more cautious. I would use 200 V. caps, just for peace of mind. What do you think?
::Rich
:Norm,
:450 V seems a little too much cushion due to price trade-offs. I shop for caps at ham swaps and at our local HSC electronic surplus. Not too many hv caps in surplus, as most electrolytics are intended for computers and switch mode power supplies. It's nice that modern caps are smaller; sometimes I try to "embed" a modern cap inside an old casing... just to keep the "look" of the older designs. I've even downloaded some artwork for old C-D, Aerovox, and Sprague caps so I can make my own outer casings to fit the "look" of old equipment. Thanks... Rich
:
::Hi Rich
::
:: I agree with you peak voltage can reach 1.414 times measured AC. I mentioned 150 volt caps as that was the rating used in AC/DC radios. Modern replacements are now marked 160 volts. This is considered working voltage. Peak voltage on caps will be higher.
::
:: In AC/DC radios tubes warm up slowly. Rectifier tubes also have a voltage drop. This will limit voltage seen on the first filter cap.
::
:: I do agree, it's better to use caps rated 200 volts but these aren't always available. Caps are smaller now so a person could use 450 volt caps for almost all radios.
::
::Norm
::
:::Norm, in one of your recent responses, you mentioned using new caps of at least 150 VDC in AA5 radios, AC-DC type. While it is true that most old radios used 150 V. caps, I always found this a bit skimpy. If you assume 120 V line, then the peak at the filter should be 120 x 1.414 or about 170 Volts. The old time caps were probably designed with some safety margin, and also tended to be physically much larger than today's electrolytics. True, the voltage will be somewhat less due to rectifier tube drop, but still close to 150V.
::: My 30+ years with Westinghouse and Siliconix cause me to be more cautious. I would use 200 V. caps, just for peace of mind. What do you think?
:::Rich
I will try to find a few more.. Rich
:Rich: Can you give me the URL address of the website where I can download old capacitor labels and graphics? Thanks - Steve W9DX
:
::Norm,
::450 V seems a little too much cushion due to price trade-offs. I shop for caps at ham swaps and at our local HSC electronic surplus. Not too many hv caps in surplus, as most electrolytics are intended for computers and switch mode power supplies. It's nice that modern caps are smaller; sometimes I try to "embed" a modern cap inside an old casing... just to keep the "look" of the older designs. I've even downloaded some artwork for old C-D, Aerovox, and Sprague caps so I can make my own outer casings to fit the "look" of old equipment. Thanks... Rich
::
:::Hi Rich
:::
::: I agree with you peak voltage can reach 1.414 times measured AC. I mentioned 150 volt caps as that was the rating used in AC/DC radios. Modern replacements are now marked 160 volts. This is considered working voltage. Peak voltage on caps will be higher.
:::
::: In AC/DC radios tubes warm up slowly. Rectifier tubes also have a voltage drop. This will limit voltage seen on the first filter cap.
:::
::: I do agree, it's better to use caps rated 200 volts but these aren't always available. Caps are smaller now so a person could use 450 volt caps for almost all radios.
:::
:::Norm
:::
::::Norm, in one of your recent responses, you mentioned using new caps of at least 150 VDC in AA5 radios, AC-DC type. While it is true that most old radios used 150 V. caps, I always found this a bit skimpy. If you assume 120 V line, then the peak at the filter should be 120 x 1.414 or about 170 Volts. The old time caps were probably designed with some safety margin, and also tended to be physically much larger than today's electrolytics. True, the voltage will be somewhat less due to rectifier tube drop, but still close to 150V.
:::: My 30+ years with Westinghouse and Siliconix cause me to be more cautious. I would use 200 V. caps, just for peace of mind. What do you think?
::::Rich