GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Melquiades Amplifier
In the Thread: Planning my DSET

Post Subject: They will light up like a Christmas treePosted by anthony on: 7/2/2015

Romy, thanks for the info on the chokes in the fullrange Milq.

Today I have ordered more Milq parts this time for the power sequencing and bleed down. I decided to go for the relay sequenced bleeders for all four power supplies and figured I would be happy with a bleed down time to 50V of about 20-30 seconds. For the four power supplies this is what I calculated:

40,000uF 200V supply = 500R resistor with initial power dissipation of 80W (purchased 500R 100W)
3,000uF 200V supply = 5K resistor with initial power dissipation of 8W (purchased 5K 10W)
9,000uF 400V supply = 2K resistor with initial power dissipation of 20W (purchased 2K 25W)
8,000uF 400V supply = 1.5K resistor with initial power dissipation of 106W (purchased 1.5K 100W)

I decided to go for large ceramic caps with good power ratings so I could avoid heatsinking and also to not rely on the short term power rating of the resistors to get through the initial high power dissipation period of the discharge. In the end the resistors I purchased are big and over-rated for the task but I am happy that I will not be pushing them anywhere near their limits so they should work well for quite some time. Looking at the calculated initial current draws I have similarly purchased relays with over-specified contact current ratings...I certainly don't want them to weld.

Downstream of each bleeder resistor will be a LED to show that charge is draining, or not. So there will be one LED to tell that AC power is available and the standby DC power supply is running, three more LED's for the power-on sequencing relays and then four LED's that will light up when the bleeder circuits are activated on power-down. That is 8 LED's on each amplifier, which is ridiculous and could make the whole thing look a little like a Christmas tree if I am not careful, but I have chosen low intensity red lights so hopefully they will ruin neither my night vision nor my impatience for bright LED's on audio gear.

Regards,

Anthony

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