T-reg: A tube voltage regulator!
This is a project for a high-voltage regulator for tube amplifiers. The design will provide anything from 50V to 500V DC and more at up to 1A DC. The tube on the assembly in the picture is an EL84 for the preamp 50mA max version. The large 6528 plug-in will provide up to 500mA. The MOSFET regulator plug-in can handle up to 1A output current.
Measurements show low output impedance of less than 100mOhms, and hum and noise below 300uV, all over the audio bandwidth. Not bad for a tube supply, and no opamps!
Of interest: I received a message from Jacques Dehaye from France, with a link to "The American Electricians Handbook". This book has a Motorola app note for an MC1466L and its cousin, the MC1566L.This is a clear diagram explaining the operation of the floating regulator. Thank you Jacques!
Also, John Walton alerted me that resistors R3 and R5 should be able to handle high voltage, up to 500V. These are available from the usual sources like Farnell and RS Components, from Multicomp and Vishay. Alternatively, you could make up R3 and R5 from two resistors in series of half the total value.
T-reg update - important
One builder of the DN2540 version of T-reg had some problems with it and I discovered that it probably is related to (re)connecting a capacitive load with the regulator live. The pass device DN2540 has a max Id of only 500mA, which is suffucient for normal use but may be exceeded in some cases when (re)connecting a cap load. I will design-in a current limiter and update the relevant pages here.
For availability of boards and parts go here!
Elektor have published the design in the March 2009 issues of the NL and UK magazines.
AudioXpress has published an adapted version in their April 2009 issue.
Download it, read it, use it, let me know what you think about it!
