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Old 29th November 2008, 04:20 PM   #21
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As I said I can't see any functionality of this 10 nf cap paralell to the switch.
The most of audio eq. like amps. usually have parallel cap. to the main switch around 4700pf or 4n7 direct or series RC 100ohm plus 4n7 to stop sparking which causes some pops or switching noises.
That resistor of 5,6Kohms is add to adapt Voltage standard U.S to EU standard of 220V old and new 230V except U.K , Austr. .....
That other Cap of 0.33mfd is very important, this combination of 0.33 mfd and 5.6Kohm resistor actually adjust RPM of the induction motor(pole shaded) type.
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Old 29th November 2008, 05:19 PM   #22
tubenut is offline tubenut  South Africa
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Quote:
If that schematic of yours is correct - with the 10 nF across the switch- the motor WILL hum. 10 nF at 50 Hz is appx. 6.5 kohm - in series with the other 5.6 k.
I have seen on especially electric drills for eg that this supressor cap over the switch is a combination resistor and cap.

Like this for eg: http://za.rs-online.com/web/0209213.html
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Old 29th November 2008, 05:52 PM   #23
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Help me to understand this, please.

A cap block DC and let through AC, ok.

How is it then possible to put a cap cross (serie) a singel breaker switch in a power supply anyway?
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Old 29th November 2008, 06:13 PM   #24
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This is the capacitor reactance formula:
Xc=1/wc
where:
w=2pi*f(circle frequency)
pi=3.14
f=frequency (Hz)
c=capacitance in F(Farads)
Xc=reactance in ohms.

So you see that Xc depends of capacitance and the frequency.
Bigger cap= lower Xc @ given frequency
lower freq.=higher Xc for given Capacitance.
For a DC currents or (0Hz) theoretical Xc will be no end big value, but just in the theory.
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Old 29th November 2008, 06:38 PM   #25
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Thank you zoranaudio

6,28x50x0,01=3,14
Is it possible the motor is a 3,14W one?

Help me with this math, please.
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Old 29th November 2008, 06:56 PM   #26
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Well we have to back in the school again
your calculations are wrong.
You must use my formula 1/2pi*f*c, but values of a capacitor must be in farads, frequency in Hz and the reactance Xc will be in ohms
10nf=0.000000010 F-farads
and calculated Xc for a 10 nf cap. @ in our case Ac mains freq=50Hz will be
Xc=318309.8861837907(ohms) and if you like in Kohms will be
Xc=318.3098861837907(Kohms)
Because Mathematic is a problem than visit this and enjoy
http://www.sengpielaudio.com/calculator-RC.htm
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Old 29th November 2008, 07:45 PM   #27
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Thanks

The calculator told me Capacitive reactance XC: infinity.

And...?
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Old 29th November 2008, 08:33 PM   #28
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Has the old Linn LP-12 supply any advantages?
http://www.diyaudio.com/forums/showt...t=#post1642945
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Old 29th November 2008, 09:45 PM   #29
AuroraB is offline AuroraB  Norway
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The reactance formula gives Xc=1/(2*pi*50*10E-9) or roughly 6.4 kohms for a 10nF cap at 50 Hz, - which I said earlier.
A capacitor across a power switch is used to quench spark noise from entering your system, -maybe causing loud pop noises through your amp and speaker..............
In this circuit, when the power switch is off, it will present another resistance of appx 6.4 k in series with the 5.6 k.
This may be the cause of the motor just vibrating, but not having enough power to drive the platter, because the total series resistance is now 12 kohms, instead of the 5.6 k in a normal operating mode.
This is why I said that this cap have a potential of causing more trouble than gain in this circuit. I also commented I could not see it in your pictures... is it maybe a tiny little gray/brown cap attached directly to the power switch?
Try to disconnect one lead at least... keep yuor volume down low...
Is the hum gone? Does operating the switch make any pop noises in your system?
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Old 29th November 2008, 09:59 PM   #30
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[QUOTE]Originally posted by AuroraB
[B]The reactance formula gives Xc=1/(2*pi*50*10E-9) or roughly 6.4 kohms for a 10nF cap at 50 Hz, - which I said earlier.
A capacitor across a power switch is used to quench spark noise from entering your system, -maybe causing loud pop noises through your amp and speaker..............
In this circuit, when the power switch is off, it will present another resistance of appx 6.4 k in series with the 5.6 k.

What is this people, please????
How can you be so smart and calculate your Xc value!!!
If you don't know what is 2+2, than use the link of the calculator previously posted.

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