Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Yosser on May 11, 2026, 04:36:09 am

Title: Tube rectifier formula
Post by: Yosser on May 11, 2026, 04:36:09 am
On this website:

https://www.valvewizard.co.uk/bridge.html

What does the symbol ^ mean in the rectifier formula?
Title: Re: Tube rectifier formula
Post by: Rontone on May 11, 2026, 05:43:24 am
A Caret '^' in this case is used for an exponent, with a 2 it would be squared

In Merlin's books this equation and others appear with the raised smaller numbers for any squaring, cubing or "to the power of"

It may be that the text formatting on the website has no option for the smaller raised numbers so the keyboard symbol ^ is used instead...


Alternatively it can be used for cat ears when leaving a comment online ₍^. .^₎⟆



Title: Re: Tube rectifier formula
Post by: Yosser on May 14, 2026, 04:04:54 am
"The data sheet will present table or graphs showing the minimum limiting resistance needed for a given application. If the transformer alone doesn't have enough resistance to meet this requirement then you need to make up the deficit by adding resistors in series with each anode. These resistors need to have a power rating that comfortably exceeds:

P = (1.1 × Idc)^2 × R"

"For the GZ34 this is 250mA for a capacitor-input rectifier"

Is Idc 0.25 for a GZ34?
Title: Re: Tube rectifier formula
Post by: sluckey on May 14, 2026, 09:29:21 am
P = (1.1 × Idc)^2 × R can also be written as P = (1.1 × Idc)2 × R if your forum supports superscript formatting. Many forums do not provide superscript formatting. available.

250mA is same as .25A.
Title: Re: Tube rectifier formula
Post by: Yosser on May 14, 2026, 01:37:44 pm
Quote from: sluckey on May 14, 2026, 09:29:21 am
P = (1.1 × Idc)^2 × R can also be written as P = (1.1 × Idc)2 × R if your forum supports superscript formatting. Many forums do not provide superscript formatting. available.

250mA is same as .25A.

But is 250ma (0.25A) the value I should be inputting in order to achieve the correct operational resistor wattage for the anode resistors for a gz34?
Title: Re: Tube rectifier formula
Post by: Rontone on May 14, 2026, 02:36:37 pm
Is this in relation to your post on GZ34 backup diodes? : https://el34world.com/Forum/index.php?topic=33465.0 (https://el34world.com/Forum/index.php?topic=33465.0)

If so what resistors are you using, you mention 47R and 22R

Do you have a schematic of the amp?

If you input those then P = (1.1 x 0.250)^2 x 47
Title: Re: Tube rectifier formula
Post by: Yosser on May 15, 2026, 05:08:00 am
Thanks to all who replied, that has been a great help.
Title: Re: Tube rectifier formula
Post by: Merlin on May 18, 2026, 11:18:29 am
Idc is the maximum average DC current you expect your circuit to consume.