Nelson Pass said:If you use a voltage reference like a TL431, it needs 0.4 mA. That
allows a loss of about 0.5V if you use a 1K resistor from the supply
to the drive for the Mosfet and use the TL431 in parallel with a cap.
Place a diode reverse biased on the resistor that biases the TL431 so
that the Gate of the Mosfet won't see any voltage on turn-off.
There. Now you can have only 4V loss = 24V.
Put a big fat capacitor to ground from the Source of the Mosfet to
reduce the ripple due to audio currents.
Thanks for the help Nelson. You are too kind.
Do you mean to take the Zen5 power supply and replace Z1 and Z2 with
TL431's (with a voltage divider network to "program" it)?
Or do you mean to take the Zen5 power supply, replace Z1 and Z2 with
the TL431's, and move D1 and D2 like the attached diagram?
I have really learned a lot, but I'm sorry my friend, I still have a long way
to go. I think the main part of my confusion with this power supply (the
original Zen 5) is a lack of understanding of how we handle when the
coils de-energize, and how we discharge the 2200uF caps (where does
the energy go and by what path?).
Thank you again,
Robert
Attachments
Time Delay Relays for Turn-On Surge Protection
I've done this with a time delay relay from an air conditioner and one of those 50W, 5- 10 ohm resistors in the transformer primary circuit, based on an old Walt Jung article in Audio, (now you know that I'm a REALLY old fart....Pass and I were probably in high school at the same time...Eh Gads !!!)
The relay can be set for whatever start-up period you want, and shorts the resistor when it is energized. When AC power drops out, (OFF switch), the resistor comes back in - pretty fool-proof. These air conditioner relays are about bullet-proof. I used two in a pair of Tigersaurus's with 300,000 mfd of capacitance each for a pair of subwoofers - it never failed to work. If you nose around a few surplus stores you can find these things - they are / were pretty common.
I've done this with a time delay relay from an air conditioner and one of those 50W, 5- 10 ohm resistors in the transformer primary circuit, based on an old Walt Jung article in Audio, (now you know that I'm a REALLY old fart....Pass and I were probably in high school at the same time...Eh Gads !!!)
The relay can be set for whatever start-up period you want, and shorts the resistor when it is energized. When AC power drops out, (OFF switch), the resistor comes back in - pretty fool-proof. These air conditioner relays are about bullet-proof. I used two in a pair of Tigersaurus's with 300,000 mfd of capacitance each for a pair of subwoofers - it never failed to work. If you nose around a few surplus stores you can find these things - they are / were pretty common.
Re: Time Delay Relays for Turn-On Surge Protection
It would be simple to bypass the thermistor or resistor using a timed relay after a few seconds if that's even needed for the F5. I just wonder if you need an elaborate softstart which will kick in after a short dropout? And then what if ?. . .etc.
dcbingaman said:
It would be simple to bypass the thermistor or resistor using a timed relay after a few seconds if that's even needed for the F5. I just wonder if you need an elaborate softstart which will kick in after a short dropout? And then what if ?. . .etc.
I have just finished some breads for breakfast. Ah . . . Papa has already been here with good advice . . .
Anyhow . . .
I have thought about the diode location as attached. Then, 2200uF could be discharged as shown.
The closed LCR circuit with initially charged cap would create an oscillation. But, the oscillation will die out with time because of the energy lost in the resistor.
>><<
Anyhow . . .
I have thought about the diode location as attached. Then, 2200uF could be discharged as shown.
The closed LCR circuit with initially charged cap would create an oscillation. But, the oscillation will die out with time because of the energy lost in the resistor.
>>
<<Attachments
discharging path and soft start ?
boyz , are you splitting the hair here ?
amp - drawing something under 3A for both channels - is pretty capable to bleed anything form cap bank - after powering off .
also - if NTC is good for NP's commercial product ( with all known safety and not-just-safety demands ) ............
sole situation when simple NTC soft start isn't up to task is in case of mains blackout (semi long ) ....... and then you'll maybe in situation to replace mains fuse in amp ..........
boyz , are you splitting the hair here ?
amp - drawing something under 3A for both channels - is pretty capable to bleed anything form cap bank - after powering off .
also - if NTC is good for NP's commercial product ( with all known safety and not-just-safety demands ) ............
sole situation when simple NTC soft start isn't up to task is in case of mains blackout (semi long ) ....... and then you'll maybe in situation to replace mains fuse in amp ..........
soft start ?
A simple relay bypassed resistor bank with delay set to 300ms solves the problem. Most of the time delay circuits are instant reset after they have been used or powered off.
on a bad day I can have upto 6 mains drop outs. Many of the occurrences arrive in pairs just a couple of seconds apart.Zen Mod said:
A simple relay bypassed resistor bank with delay set to 300ms solves the problem. Most of the time delay circuits are instant reset after they have been used or powered off.
Re: discharging path and soft start ?
I didn't intend to "split hair". My concern is/was that I am modifying the Zen 5
power supply for use with the F5, but I didn't understand certain parts of how the
circuit works. Specifically, in the Zen 5 article, Nelson states:
Diode D1 and D2 are provided to drain off C10 and C11 quickly
when the power is turned off, else the 20 Volt Gate to Source ratings
of Q3 and Q4 might be exceeded.
I did not understand how they were doing that. I _think_ I have an rudimentary
understanding of the main concepts now. However, what is, "NTC"?
Nelson mentioned using a TL431 shunt regulator. So here is a modified Zen 5
power supply circuit with the TL431's that are (so far at least) working for me.
The surprising part for me is that the resistor values need to be so high...
Anyway, for what it is worth, here is the circuit.
Thanks,
Robert
Zen Mod said:
I didn't intend to "split hair". My concern is/was that I am modifying the Zen 5
power supply for use with the F5, but I didn't understand certain parts of how the
circuit works. Specifically, in the Zen 5 article, Nelson states:
Diode D1 and D2 are provided to drain off C10 and C11 quickly
when the power is turned off, else the 20 Volt Gate to Source ratings
of Q3 and Q4 might be exceeded.
I did not understand how they were doing that. I _think_ I have an rudimentary
understanding of the main concepts now. However, what is, "NTC"?
Nelson mentioned using a TL431 shunt regulator. So here is a modified Zen 5
power supply circuit with the TL431's that are (so far at least) working for me.
The surprising part for me is that the resistor values need to be so high...
Anyway, for what it is worth, here is the circuit.
Thanks,
Robert
Attachments
F5 PS BOM
Hey,
I just finished putting together a digi-key BOM for the F5 power supply parts.
2 KC021L-ND CURRENT LIMITER INRUSH
2 RSB-2.2KRCT-ND RES 2.2K OHM 1% 3W SILICONE WW
10 PPC2.2ECT-ND RES 2.2 OHM 3W 5% MF FUSIBLE
8 P6890-ND CAPACITOR 15000UF 25V ELECT TSUP
2 VS-36MB20A-ND RECTIFIER BRIDGE 200V 35A D-34A
subtotal is $82.46
I'm just freely sharing these values / parts. Use whatever you like
Hey,
I just finished putting together a digi-key BOM for the F5 power supply parts.
2 KC021L-ND CURRENT LIMITER INRUSH
2 RSB-2.2KRCT-ND RES 2.2K OHM 1% 3W SILICONE WW
10 PPC2.2ECT-ND RES 2.2 OHM 3W 5% MF FUSIBLE
8 P6890-ND CAPACITOR 15000UF 25V ELECT TSUP
2 VS-36MB20A-ND RECTIFIER BRIDGE 200V 35A D-34A
subtotal is $82.46
I'm just freely sharing these values / parts. Use whatever you like
Re: F5 PS BOM
I used the 35v version of those caps just as a safety margin. The rails are already at 24v, so that's pretty tight given variations in line voltage, loading, etc. YMMVmerlin2069er said:Hey,
I just finished putting together a digi-key BOM for the F5 power supply parts.
2 KC021L-ND CURRENT LIMITER INRUSH
2 RSB-2.2KRCT-ND RES 2.2K OHM 1% 3W SILICONE WW
10 PPC2.2ECT-ND RES 2.2 OHM 3W 5% MF FUSIBLE
8 P6890-ND CAPACITOR 15000UF 25V ELECT TSUP
2 VS-36MB20A-ND RECTIFIER BRIDGE 200V 35A D-34A
subtotal is $82.46
I'm just freely sharing these values / parts. Use whatever you like