Voltage minimum for these power supply caps

[guilds100]

I'm building a amp the has the power supply caps wired like the ones in the sample in the picture. Im not sure what the voltages they would see in this configuration.


http://www.classictone.net/40-18024.pdf

[sluckey]

100µF @ 350VDC is a common size that will work very well with the PT and circuit in that pdf.

[Ten Over]

I'm building a amp the has the power supply caps wired like the ones in the sample in the picture. Im not sure what the voltages they would see in this configuration.


http://www.classictone.net/40-18024.pdf

Each one sees half the B+ voltage.

[guilds100]

Thanks for the replies.

[Stevem]

The answer is yes, but they each should have a 180K 2 watt balance resistor in parallel with each cap to guarantee that each cap see's no more then the 350 volts there are rated for.

[martin manning]

The answer is yes, but they each should have a 180K 2 watt balance resistor in parallel with each cap to guarantee that each cap see's no more then the 350 volts there are rated for.

No, not necessary. The CT connection insures that the voltages are equalized.

[roberto]

I confirm it is not necessary to have bleeding/balancing resistors.
I've used that configuration, with the central tap between the caps, many times and it works flawless.

[SoulFetish]

The answer is yes, but they each should have a 180K 2 watt balance resistor in parallel with each cap to guarantee that each cap see's no more then the 350 volts there are rated for.

No, not necessary. The CT connection insures that the voltages are equalized.

Manning is correct. *Not only is does the CT connection insure that the voltages are equal, but this configuration can also be set up so that the voltages are allowed to bleed off through the transformer winding resistance after the amp is powered down. (You would just need to either design the amp so that the standby switch did not interrupt the HT supply, design it without a standby switch altogether, or power the amp down and wait a short time to before switching the standby switch)

*this is incorrect. please read further.

[Ten Over]

Manning is correct. Not only is does the CT connection insure that the voltages are equal, but this configuration can also be set up so that the voltages are allowed to bleed off through the transformer winding resistance after the amp is powered down. (You would just need to either design the amp so that the standby switch did not interrupt the HT supply, design it without a standby switch altogether, or power the amp down and wait a short time to before switching the standby switch)

I'm not seeing the discharge path upon powering down. The diodes all look reverse biased to me.

[pdf64]

Consider the PT’s HT winding. Obviously the standby switch, if included as per the arrangement shown in post #1, would need to be in the ‘contacts closed’ position.

[Ten Over]

Consider the PT’s HT winding. Obviously the standby switch, if included as per the arrangement shown in post #1, would need to be in the ‘contacts closed’ position.

To discharge the cap's?

[pdf64]

Oh yeah, on another look, I take your point
I guess that the screen grid HT node will need a series pair, which would need balancing resistors.

[SoulFetish]

Manning is correct. Not only is does the CT connection insure that the voltages are equal, but this configuration can also be set up so that the voltages are allowed to bleed off through the transformer winding resistance after the amp is powered down. (You would just need to either design the amp so that the standby switch did not interrupt the HT supply, design it without a standby switch altogether, or power the amp down and wait a short time to before switching the standby switch)

I'm not seeing the discharge path upon powering down. The diodes all look reverse biased to me.

ugh.. I'm sorry. You are correct. They are reversed biased - obviously so. Embarrassing mistake on my part, but I'm going to let it stand with an asterisk to teach myself a lesson not to post such ridiculous errors.