Ok. But the voltage for B+ at 460V is a bit high. My screen voltage at pin 4 is around 450V which is not recommended for EL34 max is at 425V.
Noted but just wondering the design why never take into consideration the voltage as EL34 screen voltage is at max 425V.
Agree.
You seem to be using the nominal 320V tap today, which is too high, not only because of EL34 which has some flexibility but much worse, because of C12/C9 which are right on the edge or beyond.
So as RussC suggests, go to the next lower tap, which by the way is a much better solution than adding a resistor in series, because output voltage will be way more stable and predictable.
You seem to be using the nominal 320V tap today, which is too high, not only because of EL34 which has some flexibility but much worse, because of C12/C9 which are right on the edge or beyond.
So as RussC suggests, go to the next lower tap, which by the way is a much better solution than adding a resistor in series, because output voltage will be way more stable and predictable.
The output voltage is
Vsecout = Mains voltage/Rated Primary voltage * Rated secondary voltage * {1+transformer regulation}
If the transformer is 230:280Vac 10% regulation and mains is 6% high (243.8Vac) then the secondary voltage is:
Vout = 243.8 / 230 * 280 * {1+0.1} = 326.5Vac
Rectify that and store the peak voltage after allowing for 0.5Vf across each rectifier diode and you have 460.7Vdc stored on the capacitor.
Learn to do the arithmetic. It's not difficult.
This is an approximation to the peak voltage of a sinewave.
You are misleading anyone who believes that it can simply be applied to any mains transformer.
The rCC shown in post1 will try to charge the capacitors with an enormous initial current.
I suggest you add some resistance before or just after the power rectifier.
This will extend the life of the rectifier and of the capacitors.
The reason for the high initial current is the small value of "r"
It might be anywhere from 10r to 20r and even 20r would allow an initial pulse of ~23Apk through the rectifier and into the capacitors.
Add two or three Power Thermistors or Power resistors, to reduce the current peak.
I suggest you add some resistance before or just after the power rectifier.
This will extend the life of the rectifier and of the capacitors.
The reason for the high initial current is the small value of "r"
It might be anywhere from 10r to 20r and even 20r would allow an initial pulse of ~23Apk through the rectifier and into the capacitors.
Add two or three Power Thermistors or Power resistors, to reduce the current peak.
Have you discovered a new kind of Physics?
If so, publish your results in some peer reviewed Physics or Science and wait for grinning approval .... or laughter.
What is YOUR definition of the peak value of a sinewave? Inquiring minds want to know.
WHERE do you read that?I see NO mention of "rCC" on post#1, either typed or in the picture supplied?
Are you answering to this post?
Sure, but billions of power supplies do NOT add any extra resistance and work fine since .... forever.
Which is ....... ?
So?
You discovered nothing new, semiconductor manufacturers know that, so much so that they, precisely, specify a surge current value in the datasheets.
For 1N5408, what we are talking here, Vishay (who should know) says:
Not bad, but two or three
One is enough, in series with primary.
And typical values hover around 5 ohms.
Indeed
look again at post1 schematic.
C12 & C9 = CC
the resistances of the preceding wiring, power rectifier and transformer add up to the "r" that is often ignored.
That capacitor input filter is an RC filter but the R part is very small, written as rC or rCC in my previous posts where Members have not realised they have implemented an RC filter.
Find a Power Thermistor that has significant energy absorption and can tolerate a starting voltage differential of 460Vpk. There will be some.
C12 & C9 = CC
the resistances of the preceding wiring, power rectifier and transformer add up to the "r" that is often ignored.
That capacitor input filter is an RC filter but the R part is very small, written as rC or rCC in my previous posts where Members have not realised they have implemented an RC filter.
Find a Power Thermistor that has significant energy absorption and can tolerate a starting voltage differential of 460Vpk. There will be some.
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