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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Equivalent capacitor
Hi,
I need an electrolytic capacitor, 100V/35uF. I don't have one right now... can I use two in series, let's say 50V/68uF? The equivalent capacity should be 34uF, and since they are in series, the maximum voltage 100V. Thanks |
#2
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chibitul wrote: Hi, I need an electrolytic capacitor, 100V/35uF. I don't have one right now... can I use two in series, let's say 50V/68uF? The equivalent capacity should be 34uF, and since they are in series, the maximum voltage 100V. Thanks Hi Chibutul... I think I'd much sooner see two 17's in series... However, two caps in series isn't nearly as efficient so while you're rounding, round up. Which may (probably will) leave you with linearity problems, so were it my set I'd keep on looking for a 34 at greater than 100 volts. Take care. Ken |
#3
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Ken Weitzel wrote:
I think I'd much sooner see two 17's in series... I think Ken meant "two 17's in parallel". |
#4
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Travis Jordan wrote: Ken Weitzel wrote: I think I'd much sooner see two 17's in series... I think Ken meant "two 17's in parallel". Hi Travis... Arghhh. Very kind of you, but I just goofed. Silly old stroke damaged guy here. Forgot that series capacitance is the reciprocal of the total of the reciprocal of each cap in the series. Have to learn to think more, and type less Apologies to the op, and to all. Ken |
#5
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In article .com,
chibitul wrote: I need an electrolytic capacitor, 100V/35uF. I don't have one right now... can I use two in series, let's say 50V/68uF? The equivalent capacity should be 34uF, and since they are in series, the maximum voltage 100V. Why not just go for 47µF 100v? They're common enough, and electrolytics are rarely critical in size. -- *Why is the time of day with the slowest traffic called rush hour? Dave Plowman London SW To e-mail, change noise into sound. |
#6
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Absolutely agree...... a most common value of 47uf @ 100V should
work perfectly in almost all applications calling for 35 uf @ 100V -- Best Regards, Daniel Sofie Electronics Supply & Repair - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - "Dave Plowman (News)" wrote in message ... In article .com, chibitul wrote: I need an electrolytic capacitor, 100V/35uF. I don't have one right now... can I use two in series, let's say 50V/68uF? The equivalent capacity should be 34uF, and since they are in series, the maximum voltage 100V. Why not just go for 47µF 100v? They're common enough, and electrolytics are rarely critical in size. -- *Why is the time of day with the slowest traffic called rush hour? Dave Plowman London SW To e-mail, change noise into sound. |
#7
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Could work, depending on the circuit it is mounted.
When you put electrolytic capacitors (Aluminium, Tantalum, ...) in series you must put resistors in parallel in order to compensate the leakage currents (10 times the leakage current value in the resistors) and balance the transient voltages. If you don't do that, the first time the voltage is applied to the two caps, each capacitor won't see the same voltage and the rating may be exceeded. Shall I remind you that an overloaded capacitor may explode ? Better to wait for the good value. "chibitul" a écrit dans le message news: ... Hi, I need an electrolytic capacitor, 100V/35uF. I don't have one right now... can I use two in series, let's say 50V/68uF? The equivalent capacity should be 34uF, and since they are in series, the maximum voltage 100V. Thanks |
#8
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"chibitul" wrote in message oups.com... Hi, I need an electrolytic capacitor, 100V/35uF. I don't have one right now... can I use two in series, let's say 50V/68uF? The equivalent capacity should be 34uF, and since they are in series, the maximum voltage 100V. 47 UF/100 Volts $0.35 http://www.allelectronics.com/matrix...lytic_Cap.html N |
#9
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Ken Weitzel writes:
chibitul wrote: Hi, I need an electrolytic capacitor, 100V/35uF. I don't have one right now... can I use two in series, let's say 50V/68uF? The equivalent capacity should be 34uF, and since they are in series, the maximum voltage 100V. Thanks Hi Chibutul... I think I'd much sooner see two 17's in series... OK, we know you meant parallel. However, two caps in series isn't nearly as efficient so while you're rounding, round up. Which may (probably will) leave you with linearity problems, so were it my set I'd keep on looking for a 34 at greater than 100 volts. It's not the efficiency or linearity that would be the main issue with capacitors in series. The problem is that if the leakage resistances and capacitances are not the same, the voltage across the two caps with not be equal. So, use a higher voltage to be on the safe side if the application really requires close to the working voltage. --- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/ Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/ +Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm | Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html Note: These links are hopefully temporary until we can sort out the excessive traffic on Repairfaq.org. Important: Anything sent to the email address in the message header above is ignored unless my full name is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. |
#10
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On 13 Jul 2005 09:01:25 -0700, "chibitul"
wrote: Hi, I need an electrolytic capacitor, 100V/35uF. I don't have one right now... can I use two in series, let's say 50V/68uF? The equivalent capacity should be 34uF, and since they are in series, the maximum voltage 100V. Thanks Just in case you are ignoring your earlier post, and sorry to nag...you likely want 100uF, 35V. Tom |
#11
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Yes Tom, thanks again. I do not ignore my threads, then why would I ask
here the experts? I made a mistake, now I found the exact capacitor and I would like to install it but my wife has other plans for the evening... well, tomorrow (maybe). Thanks again, and BTW, you better "nag" than let someone stupid like me install the wrong capacitor. |
#12
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"Tom MacIntyre" bravely wrote to "All" (13 Jul 05 21:32:12)
--- on the heady topic of " Equivalent capacitor" TM From: Tom MacIntyre TM Xref: aeinews sci.electronics.repair:53130 TM On 13 Jul 2005 09:01:25 -0700, "chibitul" TM wrote: Hi, I need an electrolytic capacitor, 100V/35uF. I don't have one right now... can I use two in series, let's say 50V/68uF? The equivalent capacity should be 34uF, and since they are in series, the maximum voltage 100V. Thanks TM Just in case you are ignoring your earlier post, and sorry to TM nag...you likely want 100uF, 35V. Tom, That is exactly what I was going to say. 35uF is a pretty oddball capacitance value but 35 WVDC is a very common voltage rating. Hey, who ever heard of a 17uF electro anyways, (besides the weird old Philips stuff from Europe), ? A*s*i*m*o*v .... ELECTRON COPS STAGE COMPONENT RAID....SEVERAL CAPACITORS CHARGED! |
#13
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On 13 Jul 2005 20:18:46 -0700, "chibitul"
wrote: Yes Tom, thanks again. I do not ignore my threads, then why would I ask here the experts? I made a mistake, now I found the exact capacitor and I would like to install it but my wife has other plans for the evening... well, tomorrow (maybe). Thanks again, and BTW, you better "nag" than let someone stupid like me install the wrong capacitor. :-) Tom |
#14
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chibitul wrote:
Hi, I need an electrolytic capacitor, 100V/35uF. I don't have one right now... can I use two in series, let's say 50V/68uF? The equivalent capacity should be 34uF, and since they are in series, the maximum voltage 100V. Thanks yes -- Real Programmers Do things like this. http://webpages.charter.net/jamie_5 |
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