I'm going to experiment with both JJs and oils when my budget allows me to buy all of them at once. As far as electrolytics go, JJs seem pretty cheap to me (about half the price of Jensen electrolytics). As far as I know, Solens are basically relabeled SCRs (which I'm currently using as signal caps). However, large value high voltage SCRs are hard to get where I live. 10uF/630V seems to be the largest I can buy off the shelf. I ripped off a couple of 2100V .77uF oil caps out of an old microwave oven but haven't tried those yet, since they're so low value. According to schematics my PSU's first cap should be around 15-40uF and the rest are around 47uF. It's a slightly modified Fi Primer/Sun Audio/Je Labs/Walton 300B SE. All recommendations are welcome. And yes, the signal caps will be Jensen PIOs.
Solen is the SCR brand in North America. Good, inexpensive capacitor I highly recommend for power supply use. Get them directly from Solen in Quebec and they will not cost that much more than the much shorter lived electrolytics you are contemplating.
ASC motor run capacitors make great supply and cathode bypass cap, the series of most interest to audiophiles typical is the X386S in cylindrical aluminum cans. Larger values are typically about the size of a beer can so you need to plan accordingly.
Properly used not too close to their ratings a film cap will outlast you.
Incidentally most of these types are metallized polypropylene, film and foil types would be even larger and aren't self healing in the event of a fault. Great as a coupling cap, perhaps not as good in a psu.
ASC motor run capacitors make great supply and cathode bypass cap, the series of most interest to audiophiles typical is the X386S in cylindrical aluminum cans. Larger values are typically about the size of a beer can so you need to plan accordingly.
Properly used not too close to their ratings a film cap will outlast you.
Incidentally most of these types are metallized polypropylene, film and foil types would be even larger and aren't self healing in the event of a fault. Great as a coupling cap, perhaps not as good in a psu.
Thanks for all the info guys! Much appreciated!
I guess JJ, Solen and Jensen +++ are all decent inexpensive alternatives.
ASC Motor run seems promising if I want to try one step up...
And as said Black Gate are unbelievable, including price... I will have to sell my soul to the devil for this lot !!!!
Another capacitor question regarding CRC PSU.
My mains transformer is 440V with a bridge recitifier (diode 1N4007).
Is a 600 VDC capacitor rating enough for the smooting caps?
Is there any rule for this voltage rating except that capacitor should be able to survive +/-15% mains voltage swing?
I guess JJ, Solen and Jensen +++ are all decent inexpensive alternatives.
ASC Motor run seems promising if I want to try one step up...
And as said Black Gate are unbelievable, including price... I will have to sell my soul to the devil for this lot !!!!
Another capacitor question regarding CRC PSU.
My mains transformer is 440V with a bridge recitifier (diode 1N4007).
Is a 600 VDC capacitor rating enough for the smooting caps?
Is there any rule for this voltage rating except that capacitor should be able to survive +/-15% mains voltage swing?
A 600V capacitor is going to be beyond marginal in this application, depending on loading, transformer winding resistance and line voltage you can have anywhere from 600V to 700V on those capacitors. Solen makes some higher voltage caps, but another alternative would be to use a tube/ss bridge rectifier hybrid which would get you some time delay and sufficient voltage drop to work safely with a 630V solen if you use say a 5U4/5R4 rectifier. (Tube essentially replaces the 2 diodes in the bridge that produce the positive output - the ones in the negative leg would remain solid state 1N4007 or similar.
thanks Kevin...
Recifier tube option is noted...
Rectifier tubes was kind of my upgrade option, so if I go for all the goodies first, I get to many goodies at the same time, and can't enjoy them properly
If I have 440V +/-15% I have between 375V and 500V into the bridge! This is RMS, of course that's what I forgot so it's a factor of 1.414 above mains voltage.
So you get 500V RMS = 500 * 1.414 = 700V capacitors! WOW...
700VDC capacitors are a pain in the *** to get a hold of...
I think I only have to have the first capacitor in the CRC filter to be >630V, so I would only need one pair???
Lemme see, if not I have access to cheap 10H chokes, but these will make voltage fall to 0.9 of RMS instead of 1.414 of RMS for capacitor input... Schoolmaster says: This will not do....
I have heard it's possible to trim PS voltage with choke input supply by using a small capacitor in front of choke (which the still have to be >630V...)
Maybe I should go for the goodies and use tube rectifier, seems like the simplest solution???
All in all I soon have the parts now, but I'm not planning on using old Redmond marketing technology: Plug & pray..... So keep the good advices comin...
Lot of know-how that doesn't know how to settle down in my single, top-mounted know-how capacitor.
Recifier tube option is noted...
Rectifier tubes was kind of my upgrade option, so if I go for all the goodies first, I get to many goodies at the same time, and can't enjoy them properly
If I have 440V +/-15% I have between 375V and 500V into the bridge! This is RMS, of course that's what I forgot so it's a factor of 1.414 above mains voltage.
So you get 500V RMS = 500 * 1.414 = 700V capacitors! WOW...
700VDC capacitors are a pain in the *** to get a hold of...
I think I only have to have the first capacitor in the CRC filter to be >630V, so I would only need one pair???
Lemme see, if not I have access to cheap 10H chokes, but these will make voltage fall to 0.9 of RMS instead of 1.414 of RMS for capacitor input... Schoolmaster says: This will not do....
I have heard it's possible to trim PS voltage with choke input supply by using a small capacitor in front of choke (which the still have to be >630V...)
Maybe I should go for the goodies and use tube rectifier, seems like the simplest solution???
All in all I soon have the parts now, but I'm not planning on using old Redmond marketing technology: Plug & pray..... So keep the good advices comin...
Lot of know-how that doesn't know how to settle down in my single, top-mounted know-how capacitor.
AndrewT said:
I think I once saw some of these with a large value resistor across them (1M or 10M). It was configured like a bleeder so I figured it didn't matter much. Today, I looked at a spec sheet for a motor start cap and there were no ancilliary components mentioned
Knubie, are you rinning PP? Not sure but if you use a small cap to tune a LC filter, when you have a variable current draw, wouldn't that give a varying rail? Maybe someone else knows the answer to this.
AndrewT said:
Other than color? Seriously, a motor start capacitor is usually housed in a black plastic case while a run cap is usually in a silver metal case.
The important difference? Start caps with a rating of say 370VAC can stand that rating for only a few seconds. A run cap with a rating of 370VAC can stand that rating under continuous duty.
A start cap is usually a moderately high value (few to several hundred uF) electrolytic. Its purpose in a circuit is to shift the phase of the supply voltage and provide a boost to the motor when starting against a load. It is automatically removed from the circuit usually by a centrifugal switch, after a very short period of time (fraction of a second to a second or so). Operating a start cap on an AC circuit for more than a couple seconds will likely fry the cap and let the magic smoke out.
A run cap on the other hand is generally a lower value cap (from a few uF to about a hundred or so uF). It is designed for continuous operation in an AC circuit and as such is a heftier cap that can stand up to continuous use in a circuit.
HTH,
630V+ power supply caps
If you are looking for 700V+ power supply caps then you could check these out:
http://www.partsconnexion.com/catalog/CapacitorsElectrolytic.html
I have never tried them myself and they aren't the cheapest but apparently go upto 1000V on the 50uF and 750V on the 100uF.
If you did use them then I would certainly be interested in any feedback on them as may be considering them in a future design.
If you are looking for 700V+ power supply caps then you could check these out:
http://www.partsconnexion.com/catalog/CapacitorsElectrolytic.html
I have never tried them myself and they aren't the cheapest but apparently go upto 1000V on the 50uF and 750V on the 100uF.
If you did use them then I would certainly be interested in any feedback on them as may be considering them in a future design.
Nice tip ianc, the UNLYTIC seems promising.
The ASC X386S also seems very promising, the 440VAC have a 800VDC rating according to percyaudio.com. ASC site doesn't mention it! Strange....
The GE caps have high VDC rating but I think at least 47uf should be used, if not more, so these are a little small...
Thanks Sherman we now know how to motor start and motor run, if we get this stuff in gear also, we're up and running
The ASC X386S also seems very promising, the 440VAC have a 800VDC rating according to percyaudio.com. ASC site doesn't mention it! Strange....
The GE caps have high VDC rating but I think at least 47uf should be used, if not more, so these are a little small...
Thanks Sherman we now know how to motor start and motor run, if we get this stuff in gear also, we're up and running
This is the thread I was looking for! This gets me down to two questions. Can I consider it a rule of thumb that on current production motor run caps the WDCV rating is nearly 2X the AC rating. (370vac~700vdc) The ones I have are Mars brand made in China. Does the metal case of the motor run cap have to be isolated (insulated) from the chassis? The caps I have show no continuity between the terminals and case with a 9v megger test. I have a 500v megger I could check them with also. The reason I ask about voltage rating is the 370v caps are much smaller than the 440v ones which will make an easier fit on my chassis. My tube rectified voltage is ~ 430v. Thanks to all, Jay
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.