It is as simple as soldering 2 diodes in series.
The addition of any paralleled balancing parts, although a standard design technique to ensure voltage sharing and hence ensure the two devices can be designed for close to two times the PIV of each diode, has the opposite effect to what is trying to be achieved in this situation. Ie. in reverse bias, a diode of 20pF junction capacitance becomes 10,020 pF, and so the series connection becomes 5,010 pF, rather than 10pF.
Without the extra balancing parts, the voltage sharing performance is then based on batch tolerances of capacitance - so perhaps not appropriate to rate the two diodes with a PIV above about 1.5x. But in this situation, the PIV performance is not a design issue.
The addition of any paralleled balancing parts, although a standard design technique to ensure voltage sharing and hence ensure the two devices can be designed for close to two times the PIV of each diode, has the opposite effect to what is trying to be achieved in this situation. Ie. in reverse bias, a diode of 20pF junction capacitance becomes 10,020 pF, and so the series connection becomes 5,010 pF, rather than 10pF.
Without the extra balancing parts, the voltage sharing performance is then based on batch tolerances of capacitance - so perhaps not appropriate to rate the two diodes with a PIV above about 1.5x. But in this situation, the PIV performance is not a design issue.
Hello,
I tried the search function but still no real answers.
I was wondering about an input choke for a tube power amp that takes little current. Something like 80mA.
With a little help i can get a choke that has about 30henry, 100mA rating and 11,2 dcr because it has a heavy core. Can this be used for a tube rectifier because there will be 30H but the dcr is LOW compared to a usual 20/30 Henry.
Greetings, eduard
I tried the search function but still no real answers.
I was wondering about an input choke for a tube power amp that takes little current. Something like 80mA.
With a little help i can get a choke that has about 30henry, 100mA rating and 11,2 dcr because it has a heavy core. Can this be used for a tube rectifier because there will be 30H but the dcr is LOW compared to a usual 20/30 Henry.
Greetings, eduard
This may be a good starter ...
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Plus, email JAC with your requirements, he is extremely knowledgeable and helpful.
★ J A C - M U S I C ★ EMISSION LABS TUBES ★ YAMAMOTO SOUNDCRAFT ★ NOS TUBES ★ You must like:
Plus, email JAC with your requirements, he is extremely knowledgeable and helpful.
Hello,
I know him but this time i wanna use another supplier where i already bought some other ll2771 Lundahl chokes.
Greetings, Eduard
I know him but this time i wanna use another supplier where i already bought some other ll2771 Lundahl chokes.
Greetings, Eduard
Hello,
I know because i have been using it for a long time but only with chokes with high inductance and also dcr that is close to the ''current limiting resistor'' specified in the tube rectifier datasheet. BUT now i wanna try a choke with a dcr that is 11,2 ohm and 30 Henry. The 30 Henry will slow down the charging of the high voltage but if i need to add a resistor the positive effect of 11,2 ohm dcr will be gone i guess.
Greetings, Eduard
I know because i have been using it for a long time but only with chokes with high inductance and also dcr that is close to the ''current limiting resistor'' specified in the tube rectifier datasheet. BUT now i wanna try a choke with a dcr that is 11,2 ohm and 30 Henry. The 30 Henry will slow down the charging of the high voltage but if i need to add a resistor the positive effect of 11,2 ohm dcr will be gone i guess.
Greetings, Eduard
Read a wikipedia page or whatever about what an inductor is and what inductance is. Keywords to look for "impedance" and "current".
Is a current limiting resistor needed for choke input supplies? Surely the choke does a much better job than a resistor.
Hello,
So because of the impedance that is '' created '' by the large number of Henry the fact that there is so little DCR will not make the current at start up get high enough to damage the tube rectifier if i use the right bleeder resistance.
Greetings, Eduard
So because of the impedance that is '' created '' by the large number of Henry the fact that there is so little DCR will not make the current at start up get high enough to damage the tube rectifier if i use the right bleeder resistance.
Greetings, Eduard
eduard, please look at the tube rectifier data sheets, the impedance of the source is mentioned, just be careful to follow and you should be fine...
Hello Philippines,
I worked with the added resistor before in the past when i was still iusing capacitor input supplies. After that i started using choke input with chokes that had dcr above 200 ohm and now i found a choke with a big core so can get 30H at 100 mA with just 11,2 ohm dcr. The choke will form a high resistance to ac because of the 30 Henry is that all i need to stay saFE?
GREETINGS, EDUARD
I worked with the added resistor before in the past when i was still iusing capacitor input supplies. After that i started using choke input with chokes that had dcr above 200 ohm and now i found a choke with a big core so can get 30H at 100 mA with just 11,2 ohm dcr. The choke will form a high resistance to ac because of the 30 Henry is that all i need to stay saFE?
GREETINGS, EDUARD
as long as the source impedance agreed with datasheet specs to the tube in use, that should not matter much, it is the ripple frequency that is being addressed by the choke, in your case 100hz.. ripple currents are attenuated like so, 30H is like an impedance of like 18800 ohms, so here you see that 11.2 ohm dcr is almost nothing compared to the impedance of the choke.....
remember that a choke has an ideal resistance of 0 ohms but never happens in real life...
remember that a choke has an ideal resistance of 0 ohms but never happens in real life...
30H is nearly 10K Ohms impedance at 50Hz. You can't have the frightening peak currents we see with cap-input filters.
You do not need ANY added resistance. If you could find (afford!) a SuperConductor choke with ZERO Ohms resistance, that would be fine.
You do not need ANY added resistance. If you could find (afford!) a SuperConductor choke with ZERO Ohms resistance, that would be fine.
I used 100HZ as the ripple frequency since a full wave rectified psu will have twice the line frequency....
as an aside, ripple voltage is directly proportional to load current and inversely proportional to psu capacitance...
in the case of chokes, ripple current gets lower as inductance gets higher...
as an aside, ripple voltage is directly proportional to load current and inversely proportional to psu capacitance...
in the case of chokes, ripple current gets lower as inductance gets higher...
Hello,
I am going to use it for a DRD tube amp where the transformer will be something like 900-0-900 volts. 5r4GYB datasheet states that close to maximum voltage one should apply plate voltage after filament reached the right temperature. IF not possible always use chokle input in these conditions. Will do both.
Hope the 30 Henry will not only tackle the current but also the rise of the voltage not to much above the nominal dc voltage after a few seconds which should be close to 660 volts DC
Greetings, Eduard
I am going to use it for a DRD tube amp where the transformer will be something like 900-0-900 volts. 5r4GYB datasheet states that close to maximum voltage one should apply plate voltage after filament reached the right temperature. IF not possible always use chokle input in these conditions. Will do both.
Hope the 30 Henry will not only tackle the current but also the rise of the voltage not to much above the nominal dc voltage after a few seconds which should be close to 660 volts DC
Greetings, Eduard
the choke inductance will determine how much psu ripple is attenuated...the bigger the choke value the greater the attenuation...
Hello Philippines,
THAT is one of the first things i know about chokes. If designed properly a choke input will draw a steady current from the rectifier/transformer combo which is a big plus.
There needs to be a bleeder to make it work like a choke input no matter what happens. The higher the number of Henry the less current you need to bleed. It is to be preferred that the bleeder current is just a small part of the total current being drawn.
Normally the dc voltage with a cap input is a great deal higher than the one with a choke input. Depending upon the rectifier with a cap input you could end up arond 1200 v dc with 900 v ac input With a proper choke input you will be around 700 volts DC . SO during start up you might have a peak that rises to 800 vdc? Would be nice to be forced to buy caps with a voltage rating that is not used. Dont know if a 30 henry with 11 ohm dcr will give more dc than 30 Henry with 150 ohm dcr. If the impedance is the same they will both give the same dc? But the lower DCR will be able to act more as what some call electric flywheel because of lower dcr it can release its energy quicker?
Greetings, eduard
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