I forget - what is the supposed advantage of motor run caps (for DC power supply filters) over electrolytic? I know that audiophiles thing they are best.

Run caps cost about 10x generic electrolytics and about 2x Sprague Atoms. Plus, motor caps are quite bulky.

I believe that run caps are oil-filled film caps, not electrolytic.

Audiophiles also like NOS Sprague "Vitamin Q" caps, which are small film caps in oil, used for coupling, bypass, etc. I have a few of those which I might use to help fund my retirement.
Doug

Doug,
For one, they are high value/high current AC RATED, and capable of a high rate of discharge, and I would guess very low leakage, compared to their values. I suppose heavy metal and bass musicians might prefer those specs, if I am right. I had not heard/read of the advantage, but would seem probable.

marv

:I forget - what is the supposed advantage of motor run caps (for DC power supply filters) over electrolytic? I know that audiophiles thing they are best.
:
:Run caps cost about 10x generic electrolytics and about 2x Sprague Atoms. Plus, motor caps are quite bulky.
:
:I believe that run caps are oil-filled film caps, not electrolytic.
:
:Audiophiles also like NOS Sprague "Vitamin Q" caps, which are small film caps in oil, used for coupling, bypass, etc. I have a few of those which I might use to help fund my retirement.
:Doug

doug - I tend to think such questions are unresolvable and tend to result in unnecessary expentiture of bandwidth. Probably best to post your question here: http://antiqueradios.com/forums/

:I forget - what is the supposed advantage of motor run caps (for DC power supply filters) over electrolytic? I know that audiophiles thing they are best.
:
:Run caps cost about 10x generic electrolytics and about 2x Sprague Atoms. Plus, motor caps are quite bulky.
:
:I believe that run caps are oil-filled film caps, not electrolytic.
:
:Audiophiles also like NOS Sprague "Vitamin Q" caps, which are small film caps in oil, used for coupling, bypass, etc. I have a few of those which I might use to help fund my retirement.
:Doug

OUCH!!!!!!

:doug - I tend to think such questions are unresolvable and tend to result in unnecessary expentiture of bandwidth. Probably best to post your question here: http://antiqueradios.com/forums/
:
::I forget - what is the supposed advantage of motor run caps (for DC power supply filters) over electrolytic? I know that audiophiles thing they are best.
::
::Run caps cost about 10x generic electrolytics and about 2x Sprague Atoms. Plus, motor caps are quite bulky.
::
::I believe that run caps are oil-filled film caps, not electrolytic.
::
::Audiophiles also like NOS Sprague "Vitamin Q" caps, which are small film caps in oil, used for coupling, bypass, etc. I have a few of those which I might use to help fund my retirement.
::Doug

Oh, well. But I don't plan to take my own advice!

But unlike Carlos, I do post my e-mail address.
Doug

:OUCH!!!!!!
:
::doug - I tend to think such questions are unresolvable and tend to result in unnecessary expentiture of bandwidth. Probably best to post your question here: http://antiqueradios.com/forums/
::
:::I forget - what is the supposed advantage of motor run caps (for DC power supply filters) over electrolytic? I know that audiophiles thing they are best.
:::
:::Run caps cost about 10x generic electrolytics and about 2x Sprague Atoms. Plus, motor caps are quite bulky.
:::
:::I believe that run caps are oil-filled film caps, not electrolytic.
:::
:::Audiophiles also like NOS Sprague "Vitamin Q" caps, which are small film caps in oil, used for coupling, bypass, etc. I have a few of those which I might use to help fund my retirement.
:::Doug

Touche! Well played Carlos....

:doug - I tend to think such questions are unresolvable and tend to result in unnecessary expentiture of bandwidth. Probably best to post your question here: http://antiqueradios.com/forums/

I was hoist by my own petard.
Doug

:Touche! Well played Carlos....
:
::doug - I tend to think such questions are unresolvable and tend to result in unnecessary expentiture of bandwidth. Probably best to post your question here: http://antiqueradios.com/forums/
:

i apologize. i felt like you slammed me for a simple question and maybe i took it wrong.

:I was hoist by my own petard.
:Doug
:
::Touche! Well played Carlos....
::
:::doug - I tend to think such questions are unresolvable and tend to result in unnecessary expentiture of bandwidth. Probably best to post your question here: http://antiqueradios.com/forums/
::

Carlos - No, it is I who should apologize. I shouldn't have been so blunt.

Onward and upward.
Doug

:i apologize. i felt like you slammed me for a simple question and maybe i took it wrong.
:
::I was hoist by my own petard.
::Doug
::
:::Touche! Well played Carlos....
:::
::::doug - I tend to think such questions are unresolvable and tend to result in unnecessary expentiture of bandwidth. Probably best to post your question here: http://antiqueradios.com/forums/
:::

:I forget - what is the supposed advantage of motor run caps (for DC power supply filters) over electrolytic? I know that audiophiles thing they are best.
:
:Run caps cost about 10x generic electrolytics and about 2x Sprague Atoms. Plus, motor caps are quite bulky.
:
:I believe that run caps are oil-filled film caps, not electrolytic.
:
:Audiophiles also like NOS Sprague "Vitamin Q" caps, which are small film caps in oil, used for coupling, bypass, etc. I have a few of those which I might use to help fund my retirement.
:Doug

i have a couple of 10 uf caps that came off dishwasher motors that are almost new .these are unpolarized caps made in germany. i don't remember if they were motor start or run caps but at 10 uf they should be run caps.i was going to use 1 of them to replace a line cord res. on a 68 v.tube lineup in a curtain burner as these are not very big and would mount under the chassis.i thought maybe they wouldn't work right and ended up using a 8.2 uf solen cap which works fine but seems to have slightly low filament v. so maybe i should have tried one i wish i wasn't such a boob when it comes to math but as near as i could figure the 10 uf would have been produced closer to 68 v. .i guess though as the set plays fine, maybe having a slightly reduced v. will make the tubes last longer.butch

Butch: Somewhere on the web is a spreadsheet-type calculation that does the math for sizing a dropping cap to replace a resistance line cord. But I don't seem to have it bookmarked.

But the answer most always seems to be around 8-10uF. Larger value caps give less voltage drop.
Doug

:
:i have a couple of 10 uf caps that came off dishwasher motors that are almost new .these are unpolarized caps made in germany. i don't remember if they were motor start or run caps but at 10 uf they should be run caps.i was going to use 1 of them to replace a line cord res. on a 68 v.tube lineup in a curtain burner as these are not very big and would mount under the chassis.i thought maybe they wouldn't work right and ended up using a 8.2 uf solen cap which works fine but seems to have slightly low filament v. so maybe i should have tried one i wish i wasn't such a boob when it comes to math but as near as i could figure the 10 uf would have been produced closer to 68 v. .i guess though as the set plays fine, maybe having a slightly reduced v. will make the tubes last longer.butch

:Butch: Somewhere on the web is a spreadsheet-type calculation that does the math for sizing a dropping cap to replace a resistance line cord. But I don't seem to have it bookmarked.
:
:But the answer most always seems to be around 8-10uF. Larger value caps give less voltage drop.
:Doug
:
::
::i have a couple of 10 uf caps that came off dishwasher motors that are almost new .these are unpolarized caps made in germany. i don't remember if they were motor start or run caps but at 10 uf they should be run caps.i was going to use 1 of them to replace a line cord res. on a 68 v.tube lineup in a curtain burner as these are not very big and would mount under the chassis.i thought maybe they wouldn't work right and ended up using a 8.2 uf solen cap which works fine but seems to have slightly low filament v. so maybe i should have tried one i wish i wasn't such a boob when it comes to math but as near as i could figure the 10 uf would have been produced closer to 68 v. .i guess though as the set plays fine, maybe having a slightly reduced v. will make the tubes last longer.butch

:Butch: Somewhere on the web is a spreadsheet-type calculation that does the math for sizing a dropping cap to replace a resistance line cord. But I don't seem to have it bookmarked.
:
:But the answer most always seems to be around 8-10uF. Larger value caps give less voltage drop.
:Doug
:

::Folks, Fred Crews here. The motor run caps are great for the series filament radios to act as a line cord resistor. The big advantage is that they do not generate any heat and can be put in the chassis. To compute the value of C, one needs to first calculate the total voltage drop of the tubes themselves and then solve for capacitive reactance necessary to give the total impedance in a series circuit of 120 volts. Knowing that reactance, then using the equation of C=1/(2XpiX60) solve for the value of C. It will usually be in the order of a few microfarad up to say about 10. Do not use radio filter capacitors!! works great!
Some overhead ventilating fans use these capacitors and use various values of C for different motor speeds. Good Luck!

::i have a couple of 10 uf caps that came off dishwasher motors that are almost new .these are unpolarized caps made in germany. i don't remember if they were motor start or run caps but at 10 uf they should be run caps.i was going to use 1 of them to replace a line cord res. on a 68 v.tube lineup in a curtain burner as these are not very big and would mount under the chassis.i thought maybe they wouldn't work right and ended up using a 8.2 uf solen cap which works fine but seems to have slightly low filament v. so maybe i should have tried one i wish i wasn't such a boob when it comes to math but as near as i could figure the 10 uf would have been produced closer to 68 v. .i guess though as the set plays fine, maybe having a slightly reduced v. will make the tubes last longer.butch

::Butch: Somewhere on the web is a spreadsheet-type calculation that does the math for sizing a dropping cap to replace a resistance line cord. But I don't seem to have it bookmarked.
::
::But the answer most always seems to be around 8-10uF. Larger value caps give less voltage drop.
::Doug
::
:
:
:
:::Folks, Fred Crews here. The motor run caps are great for the series filament radios to act as a line cord resistor. The big advantage is that they do not generate any heat and can be put in the chassis. To compute the value of C, one needs to first calculate the total voltage drop of the tubes themselves and then solve for capacitive reactance necessary to give the total impedance in a series circuit of 120 volts. Knowing that reactance, then using the equation of C=1/(2XpiX60) solve for the value of C. It will usually be in the order of a few microfarad up to say about 10. Do not use radio filter capacitors!! works great!
:Some overhead ventilating fans use these capacitors and use various values of C for different motor speeds. Good Luck!

yes they do work great i have done this a few times without any problems.i did find a chart which didn't list all the tube lineups v.but had mine which was 68 v. using a 10 uf cap .i used an 8.2 cap which worked fine but it might have been a little better with the 10 uf but i'm happy with it.butch
:
:
:
:::i have a couple of 10 uf caps that came off dishwasher motors that are almost new .these are unpolarized caps made in germany. i don't remember if they were motor start or run caps but at 10 uf they should be run caps.i was going to use 1 of them to replace a line cord res. on a 68 v.tube lineup in a curtain burner as these are not very big and would mount under the chassis.i thought maybe they wouldn't work right and ended up using a 8.2 uf solen cap which works fine but seems to have slightly low filament v. so maybe i should have tried one i wish i wasn't such a boob when it comes to math but as near as i could figure the 10 uf would have been produced closer to 68 v. .i guess though as the set plays fine, maybe having a slightly reduced v. will make the tubes last longer.butch

Hi, Fred. To compute the required capacitive impedance to reduce the line voltage by so many volts, you need to take into account that the voltage drop across the cap will be essentially 90 deg out of phase with the voltage across the radio itself. So a little trig is involved.
Doug

::
::::Folks, Fred Crews here. The motor run caps are great for the series filament radios to act as a line cord resistor. The big advantage is that they do not generate any heat and can be put in the chassis. To compute the value of C, one needs to first calculate the total voltage drop of the tubes themselves and then solve for capacitive reactance necessary to give the total impedance in a series circuit of 120 volts. Knowing that reactance, then using the equation of C=1/(2XpiX60) solve for the value of C. It will usually be in the order of a few microfarad up to say about 10. Do not use radio filter capacitors!! works great!