[sdiy] anyone tried this SMPSU?

Mike Bryant mbryant at futurehorizons.com
Wed Feb 17 20:38:44 CET 2021

Actually you can get isolated POL supplies.  Slightly more expensive but not silly money, though they tend to need quite a bit of post filtering.  I use them on my standalone mic preamplifiers/ADCs, and they help avoid all sorts of earth loops and so on without putting a transformer in the audio path.

From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of thresholdpeople via Synth-diy
Sent: 17 February 2021 18:34
To: ColinMuirDorward
Cc: Brian Willoughby; *SYNTH DIY
Subject: Re: [sdiy] anyone tried this SMPSU?

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Wednesday, February 17, 2021 9:43 AM, ColinMuirDorward <colindorward at gmail.com<mailto:colindorward at gmail.com>> wrote:

Is anyone regulating SMPS down for example from 15v to 12v? My understanding is that HF noise will pass right through the lm317, etc, and yet I see it is very popular to use SMPS brick/wallwart connecting to a eurorack case which then uses linear regulators to derive 12v. I was just looking at the behringer euro supply, and I think it actually uses two SMPSUs: one in the power brick, and then another in the module itself. I'm sure it works, but is that a little goofy?

This is typically referred to as linear post-regulation. There are some linear regulators that can go from 15v to 12v, but most commonly you'll need higher input voltage, 18 or 20v. There was an EEVblog episode about this... This is not linear post regulation, but seems to me a great solution - a capacitance multiplier circuit - for post switcher ripple remover: https://www.youtube.com/watch?v=wopmEyZKnYo. You'll still need more than 15v to regulate down though.

And DC to DC switch mode supplies are very common. Not sure one way or the other about having a power supply on each module, but it is an interesting method for sure. Sometimes this is referred to as POL, or point-of-load, power supplies. The advantages of these are that they are relatively cheap and tiny, and for some of them, they can put out huge amounts of current... though that aspect is likely not needed in this case. POL supplies are not 0v isolated, which again, depending on how you do it, may not be a big deal at all.
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