[Matron]

On 11 July, 18:13, Ian Bell wrote:
I am building an audio mixer that uses 9 pairs of tubes and the heaters
take 12V at a total of 5.4 amps dc. *I don't fancy building a single
6amp 12V linear regulator so as I see it I have a couple of choices.

1. Build nine separate 1 amp or 5 separate 2 amp regulators - a bit
cumbersome but workable.

2. Use an off the shelf 12V SMPSU. I have looked at a few examples. Most
seems to switch at around 25KHz and at rated current have about 200mV pp
ripple on the output (content unspecified but I bet there's some 25KHz
in there).

As a low cost, small size way of achieving what I want an SMPSU seems
the way to go but this 25KHz power circuit worries me. OK, the PSU will
be in a separate screened box some way from the mixer's sensitive
circuits but still am am a little concerned.

Anyone have any experience of using SMPSUs for heater supplies in low
level audio or any other comments or ideas??

Cheers

Ian

Hi
Check out the amateur radio suppliers. Several 20A SM supplies with
adjustable voltage and switching frequency are available.

Regards
Todd