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-   -   Power unused circuits off: should power grounds be switched? (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched.html)

analog_sa 18th November 2019 08:12 AM

Quote:

Originally Posted by zgtc (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched-post5978869.html#post5978869)
I want to also be able to power unused circuits off.

And the reason for this complication is? Just to please Greta? :D

Why use relays instead of mosfets?

Vovk Z 18th November 2019 08:20 AM

Quote:

Originally Posted by zgtc (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched-post5979421.html#post5979421)
If Iím not mistaken, one of the advantages of latching relays is that they only consume power when switching takes place?

Yes.

zgtc 18th November 2019 08:36 AM

Hi,
Quote:

Originally Posted by analog_sa (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched-post5979503.html#post5979503)
And the reason for this complication is? Just to please Greta? :D

I donít know who that Greta is, but reasons explained in first and 7th post, more specifically
Quote:

I'm going to use DC power (avoiding AC mains completely). In this scenario, I think trying to avoid over-dimensioning the initial DC source and also avoid wasted unused power makes sense.
As for:

Quote:

Originally Posted by analog_sa (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched-post5979503.html#post5979503)
Why use relays instead of mosfets?

I donít know how that would work, sorry for my ignorance. Also, would that approach allow the Arduino to manage the timing of those on/offs?

Thank you

analog_sa 18th November 2019 08:46 AM

Suitable mosfets are better than relays in the ON position and worse in the OFF. Don't make clicks, don't age, easy to control multiple switches.

analog_sa 18th November 2019 08:52 AM

Quote:

Originally Posted by zgtc (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched-post5979518.html#post5979518)
Hi, I donít know who that Greta is, but reasons explained in first and 7th post, more specifically

Read the 7th post. Looks like you do know Greta after all :p

Have you calculated the savings? Does it amount to whole milliwatts or just fractions?

zgtc 18th November 2019 09:29 AM

Quote:

Originally Posted by analog_sa (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched-post5979525.html#post5979525)
Suitable mosfets are better than relays in the ON position and worse in the OFF. Don't make clicks, don't age, easy to control multiple switches.

Still, would that approach allow the Arduino to manage the timing of those on/offs?

Quote:

Originally Posted by analog_sa (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched-post5979529.html#post5979529)
Read the 7th post. Looks like you do know Greta after all :p

If you say so

Quote:

Originally Posted by analog_sa (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched-post5979529.html#post5979529)
Have you calculated the savings? Does it amount to whole milliwatts or just fractions?

Savings around full watts, yes. Phono amp can probably consume 0,25W per channel, but the RPi will consume 10W (5V@2A) if using display, etc.

stocktrader200 18th November 2019 06:21 PM

unless your chip draws alot, don't bother. I'm using an MKR1010 and it draws maybe 50ma. The I2C and logic draws almost nothing while in standby (not being accessed mode)
latching relays only draw while changing state. you will have to program in a latching pulse for both the "on" and "off" states of the relays.

I used CD4052 cmos switches for analog inputs on an old car stereo that is still a great sounding unit. I also used CD4066 for a stereo 1024 step volume control back in 85 or 86 that still outperforms most volume pots.

kodabmx 19th November 2019 12:35 AM

Quote:

Originally Posted by zgtc (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched-post5979551.html#post5979551)
Phono amp can probably consume 0,25W per channel

Damn. one of my tube phono stages uses almost 80W from the wall! 10 tubes, 2 for voltage regulation, all running from 12V with boost converters.

zgtc 19th November 2019 10:53 AM

Quote:

Originally Posted by stocktrader200 (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched-post5980080.html#post5980080)
unless your chip draws alot, don't bother. I'm using an MKR1010 and it draws maybe 50ma. The I2C and logic draws almost nothing while in standby (not being accessed mode)

It's not the MCU that worries me (Arduino consumes much less, but it also will be on all the time). The problem is the RPi, which consumes quite a lot more and it needs software/logic to power off gracefully.

Quote:

Originally Posted by stocktrader200 (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched-post5980080.html#post5980080)
latching relays only draw while changing state. you will have to program in a latching pulse for both the "on" and "off" states of the relays.

cool, that was the main idea

Quote:

Originally Posted by stocktrader200 (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched-post5980080.html#post5980080)
I used CD4052 cmos switches for analog inputs on an old car stereo that is still a great sounding unit. I also used CD4066 for a stereo 1024 step volume control back in 85 or 86 that still outperforms most volume pots.

mmm will have to look for it, but I don't think/remember CMOS switches for 4A. For instance, CD4052 & CD4066 DS state "DC input current Ī10mA". If there are other chips with higher input current tolerance, then it'd be a fantastic solution, yes, since I don't care too much for the audio signal quality here, we're talking about power rails. Will do my homework, thank you.

Quote:

Originally Posted by kodabmx (https://www.diyaudio.com/forums/power-supplies/345410-power-unused-circuits-power-grounds-switched-post5980451.html#post5980451)
Damn. one of my tube phono stages uses almost 80W from the wall! 10 tubes, 2 for voltage regulation, all running from 12V with boost converters.

Yup, but this is op-amp based, completely different approaches.

Thank you again, everyone

zgtc 20th November 2019 09:12 AM

2 Attachment(s)
I might've found a way to avoid relays, using a power switch per each optional rail, at least for the 5V@3A. For instance, AP22815BWT-7. If I'm not mistaken this chip accepts a Input Voltage Range of 3.0V ~ 5.5V, and has an Enable input that acts as the switcher. It even has Overcurrent, Short-Circuit and Thermal Protection, Output Reverse-Voltage/Current Protection, Undervoltage Lockout etc. The EN feature is described as:

Quote:

ON/OFF Input Operator
The EN input allows the output current to be switched on and off using a GPIO compatible input. The high signal (switch on) must be at least 1.2V and the low signal (switch off) no higher than 0.4V. This pin should not be left floating. It is advisable to hold the EN signal low when applying or removing power
Would anyone here please confirm this is a valid approach or I'm completely nuts? If this is valid, I'd need to find a similar product for +12V and for -12V rails.

Thank you so much


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