Author Topic: boosting cap voltage and or uf rating  (Read 1999 times)

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Offline Jesset1996.5Topic starter

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boosting cap voltage and or uf rating
« on: October 14, 2015, 03:40:27 am »
im currently working on an old tube radio and some of the caps are of a voltage that i simply can not buy anymore.is there a way i can combine capacators to boost voltage or uf? im new to substatuting caps. usually i dont need to do this. please ignore my bad spelling and grammer, its a buissy day in my small electronics lab :palm:
 

Offline JoeB83

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Re: boosting cap voltage and or uf rating
« Reply #1 on: October 14, 2015, 03:50:09 am »
Safest policy is to go for a higher voltage rating. Example, 100u/25V, go for 100u/35V or 100u/50V. What values do you need to replace? I know tubes can run pretty high voltages-my only project I've done with tubes ran on 48V, I used all 63V caps.
 

Offline Jesset1996.5Topic starter

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Re: boosting cap voltage and or uf rating
« Reply #2 on: October 14, 2015, 05:05:18 am »
Safest policy is to go for a higher voltage rating. Example, 100u/25V, go for 100u/35V or 100u/50V. What values do you need to replace? I know tubes can run pretty high voltages-my only project I've done with tubes ran on 48V, I used all 63V caps.
600v 300v and 400v
 

Offline JoeB83

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Re: boosting cap voltage and or uf rating
« Reply #3 on: October 14, 2015, 05:28:00 am »
Capacitance values? (usually in uF.....in old stuff, sometimes marked as mfd.)
 

Offline Jesset1996.5Topic starter

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Re: boosting cap voltage and or uf rating
« Reply #4 on: October 14, 2015, 05:38:00 am »
Capacitance values? (usually in uF.....in old stuff, sometimes marked as mfd.)
  x4 .10 mfd 400v , x4 .05mfd 600v ,.005mfd 600v, .1mfd 600v , x3 .003 mfd 600v, .02mfd 600v .02mfd 300v
ihave already found the 20mfd , 30mfd and 50 mfd 150v caps. it goes to a rca 46x23 from 1939
 

Offline Zero999

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Re: boosting cap voltage and or uf rating
« Reply #5 on: October 14, 2015, 07:49:42 am »
Capacitance values? (usually in uF.....in old stuff, sometimes marked as mfd.)
  x4 .10 mfd 400v , x4 .05mfd 600v ,.005mfd 600v, .1mfd 600v , x3 .003 mfd 600v, .02mfd 600v .02mfd 300v
ihave already found the 20mfd , 30mfd and 50 mfd 150v caps. it goes to a rca 46x23 from 1939
It is possible to connect capacitors in series to increase the voltage rating, but it's generally not recommended and high value resistors in parallel are often required to help them share the voltage.

Those values should be widely available and if they're not, what's there should be close enough.

They'll be marked differently, so for 0.10mfd, look for 100nF or 0.1uF. For the others you might not be able to get the exact value so go for the nearest E6 value (10, 15, 22, 33, 47, 68 multiplied by a power of 10), so for 0.05mf go for 47nF which should be near enough.
 

Offline JoeB83

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Re: boosting cap voltage and or uf rating
« Reply #6 on: October 14, 2015, 07:51:15 am »
Capacitance values? (usually in uF.....in old stuff, sometimes marked as mfd.)
  x4 .10 mfd 400v , x4 .05mfd 600v ,.005mfd 600v, .1mfd 600v , x3 .003 mfd 600v, .02mfd 600v .02mfd 300v
ihave already found the 20mfd , 30mfd and 50 mfd 150v caps. it goes to a rca 46x23 from 1939
It is possible to connect capacitors in series to increase the voltage rating, but it's generally not recommended and high value resistors in parallel are often required to help them share the voltage.

Those values should be widely available and if they're not, what's there should be close enough.

They'll be marked differently, so for 0.10mfd, look for 100nF or 0.1uF. For the others you might not be able to get the exact value so go for the nearest E6 value (10, 15, 22, 33, 47, 68 multiplied by a power of 10), so for 0.05mf go for 47nF which should be near enough.

What he said.  :D
 


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