I'm planning to re-cap my Eico oscilloscope, and it has three .1uf/1500 volt capacitors.
From what I gather, putting 2 caps in parallel, won't increase the WVDC, only putting them in series will.
So basically I would need 4 capacitors which are around 600 OR 650v, pair in both series & parallel (.1 600) to get 1200-1300v at .1 ?
Would 1200wvdc generally be enough for this type of rig?
Also, perhaps maybe just two .1's in series for .05 may work in this app? The unit works ok with the old ones so far, just trying to get and idea of what's best. I think the only place that has the HV caps is Allied, and am trying to delay an order from them, as I just spent $100 for a bunch of new caps.
Just trying to cover all bases, I haven't really calibrated it yet, but the signal from my calibrator looks a bit more sawtooth than square wave (wonder what's up with that), plus the wave is a bit curved across the screen rather that straight (very slightly U shaped).

Frank, I wouldn't cheat on the original cap voltage ratings. Putting them in series does increase the voltage rating, but reduces the cap value, e.g., four 0.1-uF caps in series will equal 0.025 uF.

$100 should buy a lot of caps. Where did you buy them?

:I'm planning to re-cap my Eico oscilloscope, and it has three .1uf/1500 volt capacitors.
:From what I gather, putting 2 caps in parallel, won't increase the WVDC, only putting them in series will.
:So basically I would need 4 capacitors which are around 600 OR 650v, pair in both series & parallel (.1 600) to get 1200-1300v at .1 ?
:Would 1200wvdc generally be enough for this type of rig?
:Also, perhaps maybe just two .1's in series for .05 may work in this app? The unit works ok with the old ones so far, just trying to get and idea of what's best. I think the only place that has the HV caps is Allied, and am trying to delay an order from them, as I just spent $100 for a bunch of new caps.
:Just trying to cover all bases, I haven't really calibrated it yet, but the signal from my calibrator looks a bit more sawtooth than square wave (wonder what's up with that), plus the wave is a bit curved across the screen rather that straight (very slightly U shaped).

I got them at an old store in Winston-Salem, "Electronics Supply", got 59 for $100, for varying projects I have going on. But they didn't have anything higher than 600v or so. I will have to wait and try mail order.
Thanks.

Frank,
I'm not familar with the Eico scope, but if you're using a probe connected to your calibrator, it can affect the waveform, as will a length of coax cable, because of inherent capacitance. Older high end (Tektronix) probes have a compensation adjustment that will make a square wave look right.
Also try DC coupling vs AC coupling if the scope has that option.

marv

:I'm planning to re-cap my Eico oscilloscope, and it has three .1uf/1500 volt capacitors.
:From what I gather, putting 2 caps in parallel, won't increase the WVDC, only putting them in series will.
:So basically I would need 4 capacitors which are around 600 OR 650v, pair in both series & parallel (.1 600) to get 1200-1300v at .1 ?
:Would 1200wvdc generally be enough for this type of rig?
:Also, perhaps maybe just two .1's in series for .05 may work in this app? The unit works ok with the old ones so far, just trying to get and idea of what's best. I think the only place that has the HV caps is Allied, and am trying to delay an order from them, as I just spent $100 for a bunch of new caps.
:Just trying to cover all bases, I haven't really calibrated it yet, but the signal from my calibrator looks a bit more sawtooth than square wave (wonder what's up with that), plus the wave is a bit curved across the screen rather that straight (very slightly U shaped).

I was just using regular test leads, but I do have a special probe or two that came with it, will have to locate them. That's a good point. Thanks

Frank,
If its like mine, model 460, you will want to keep any strong magnetic field (including motors & magnets) away from the scope and CRT, as it does not have any shielding other then the case. The magnetic field will change/distort the waveform.

David S.

:I was just using regular test leads, but I do have a special probe or two that came with it, will have to locate them. That's a good point. Thanks

:Frank,
:If its like mine, model 460, you will want to keep any strong magnetic field (including motors & magnets) away from the scope and CRT, as it does not have any shielding other then the case. The magnetic field will change/distort the waveform.
:
:David S.
:
::I was just using regular test leads, but I do have a special probe or two that came with it, will have to locate them. That's a good point. Thanks

David S,

Since you have an EICO 460 scope, may I make a suggestion? That suggestion is to not leave the scope on for an extended time. I have a 460 minus the power transformer that I forgot and left on (I had the intensity turned down) over a weekend two times. The first time I came into the shop after the weekend and found the fuse and transformer blown. I ordered a new transformer from EICO and all was well until I did the same thing again. The last time there wasn't anywhere to order the transformer so the scope got put into the storage room to collect dust.

Radiodoc

Good advice, Radiodoc, that's essential. I've even had a laptop computer once burn out the transformer when left on overnight.
As far as the caps go, I'll wait until I order from Allied again, as they have the .1's at high voltages, even 3000v or so.
What I was saying orginally though, is that you can use 4 caps in a pinch to equal one.
Two parallel pairs of .1 600v caps in series would make a .1 at 1200v

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