Check it. IIRC this cap only blocks the DC Volts across the choke, which is surely 2V or less. So you need >2V rating.
An extreme (real unlikely) case would be large 0.1Hz signal which would try to swing large voltage into the cap with little voltage out. *But* you would need about a literal Ton of choke to support such swing, so this won't happen.
Start-up may try to swing voltage but again the choke won't support it for long, and electrolytics are pretty good about short-term overvoltage (big caps take time to heat-up).
For military work the cap must support the "ripple current" which is the audio current to the load. A physically large cap is normally fine all across the audio band. And in unclipped speech/music the average (heating) current is less than 1/10th of the peak current. Taking peak as 3A then the "average ripple" is 300mA and any speaker-size cap will stand that for decades. (For reference: a cheap 1000uFd 16V cap can carry 890mA, a 4,700uFd 35V 2,700mA, steady.)
In global NFB amps we sometimes use an output cap as small as 1,000uFd, but this is a deluxe amp and I assume >4,000uFd is typical for negligible loss and good damping to 40Hz.
So a >2V cap is probably fine, but uncommon, and too small to be impressive. 1,000uFd 6V is rated 500mA and might heat in steady test-tone power output tests. 4,700uFd 35V will take steady full output so is "overkill" for speech/music, and that's fine for us.
Thanks PRR, it's "Kick" from the choke I worried about, that's why I over rated the output cap. Looks like I have been worrying too much.😎
Perhaps that was the MOAMOFO and I run 37v at 4.65A and use a big 600w IXYS dissipating about 150w and cooled with a CPU cooler.
https://www.diyaudio.com/forums/pass-labs/313649-build-mofo-173.html#post5661773
I just made a new power supply called the SLB that can provide 4.4A with only 1mV ripple and two 15,000u bulk caps. This could be very useful for MoFo.
The SLB (Smooth Like Butter) Active Rect/CRC/Cap Mx Class A Power Supply GB
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That's why I was asking about the possibility of a single positive rail version of the SLB over on your SLB group buy thread.
Adjustements
Good evening, gentlemen.
I ask the question again because modified alienation.
For the Mofo (version 19 Volts and 193 T Hammond).
I just tested a linear alimantation with a 300 VA transformer (2 x 15 vots) plus a diode bridge and a 44,000 µF filter.
I mounted a series of resistors to drain 1.7A, the voltage is 20.5 Volts in charge.
For this voltage there, the 1.7A setting is correct?
By thanking you in advance.
Good evening, gentlemen.
I ask the question again because modified alienation.
For the Mofo (version 19 Volts and 193 T Hammond).
I just tested a linear alimantation with a 300 VA transformer (2 x 15 vots) plus a diode bridge and a 44,000 µF filter.
I mounted a series of resistors to drain 1.7A, the voltage is 20.5 Volts in charge.
For this voltage there, the 1.7A setting is correct?
By thanking you in advance.
> Which voltage are you referring to,
A moment's thought might clear it up.
1.8A in a 2r choke is indeed 3.6V.
1.8A peak swing across the MOSFET and the *load* is (assuming 8 Ohm load) is 14.4V.
This suggests 2V+14.4V or 16.4V total supply.
2r dead load with 8r active load is a bit on the lossy side, but we use what we can get.
A moment's thought might clear it up.
1.8A in a 2r choke is indeed 3.6V.
1.8A peak swing across the MOSFET and the *load* is (assuming 8 Ohm load) is 14.4V.
This suggests 2V+14.4V or 16.4V total supply.
2r dead load with 8r active load is a bit on the lossy side, but we use what we can get.
Hi all,
Anyone have a spare pair of PCB’s for the MOFO? Been looking to build a pair but the DIY store is out of stock and has been for some time….
Not looking for freebies, just looking for boards!
Thanks Dave
Anyone have a spare pair of PCB’s for the MOFO? Been looking to build a pair but the DIY store is out of stock and has been for some time….
Not looking for freebies, just looking for boards!
Thanks Dave
How much would be to ship to Toronto?
After I'm done with the PTSD therapy I may build this amp. It is similar to the SEWA I built 12 years ago.
Question to those who use microwave choke
Do this transformer work as a choke, I have one plus I have a Panasonic older microwave I could remove the second transformer from that.
I'm not using it at all once or twice a year.
PANASONIC B600B7600AP ( MD-103ATR-1 ) Microwave Transformer NN-SU676B | eBay
Thanks
The question is how good these transformers handles DC current as they have no airgap. But as far as I remember they are said to work fine. Don't think I have seen any measurements that confirms that.
gaborbela,
Sorry I only had the 1 spare set of boards and they are on their way to nzlowie.(Dave)
Steve.
Sorry I only had the 1 spare set of boards and they are on their way to nzlowie.(Dave)
Steve.
If anyone wants to use an microwave transformer as choke.
Usually those are welded but easy to open with a small hacksaw. So you can add an air gap. Also the coil formers are easy to rewind.
Usually those are welded but easy to open with a small hacksaw. So you can add an air gap. Also the coil formers are easy to rewind.