Power switch for a single module

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Fidi
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Power switch for a single module

Post by Fidi » Mon Feb 22, 2021 4:21 pm

I‘m using my Bitbox Micro not very often, and this thing get‘s quite hot... to save some of its lifetime, I‘m looking for a power switch to put between busboard and module, so I can switch it off when not using it. Is there a module for this already existing? Is DIY as simple as taking a DPST-switch (and a 2hp panel) to switch postive and negative rail connection to the module (0V always connected)? Or might this be harmful in any way?

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Grumble
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Re: Power switch for a single module

Post by Grumble » Mon Feb 22, 2021 4:25 pm

Using a dpst switch is ok to switch off the power to a module, but be sure to remove any cv-es because it is uncertain what a voltage/current will do to the input circuit of an unpowered module.

Fidi
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Re: Power switch for a single module

Post by Fidi » Mon Feb 22, 2021 4:30 pm

Ah, thanks for this warning. So even if I would put it in a 4ms pod, it is recommended to disconnect cv‘s (and the MIDI input?) to prevent damage?

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Re: Power switch for a single module

Post by Grumble » Mon Feb 22, 2021 4:49 pm

Midi input is optical isolated, so that is safe

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Re: Power switch for a single module

Post by Fidi » Mon Feb 22, 2021 5:38 pm

Thanks, I think I‘ll try it with the Switch and pay attention to disconnect cv‘s.

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Re: Power switch for a single module

Post by nexgen23 » Mon Feb 22, 2021 9:32 pm

Grumble wrote:
Mon Feb 22, 2021 4:25 pm
Using a dpst switch is ok to switch off the power to a module, but be sure to remove any cv-es because it is uncertain what a voltage/current will do to the input circuit of an unpowered module.
Wondering if this is a concern with separate cases, ie if all cases power off with separate switches, do you need to unpatch them before turning them off? Or is this just something to do with turning off one modules using a switch? I have been turning my cases off separately and want to make sure I am. Not damaging anything, though this is the first time I have heard this mentioned.

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Re: Power switch for a single module

Post by Grumble » Tue Feb 23, 2021 2:05 am

As I mentioned before, it is uncertain what an unpowered module will do with a control voltage at its input.
To know if a control voltage can do harm to the input circuit of an unpowered module you have to look at the schematics and read the datasheets of the used components of the input circuit to be sure.
To avoid all this, you just unplug the inputs before unpowering this single module.

https://www.analog.com/en/analog-dialog ... -amps.html
This is an article on the analog devices website about this topic.

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Re: Power switch for a single module

Post by helix » Tue Feb 23, 2021 3:33 am

Hmmm, i have two separate power supplies in one case and always switch them on a few seconds after the other, and the same when powering down. 168HP over 9U. Never had a problem, but also never thought about it really! Always something to worry about with eurorack eh!
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Re: Power switch for a single module

Post by Grumble » Tue Feb 23, 2021 7:13 am

Well I guess that most of the times it’s okay to power a module(S) on or off while the inputs are hot. It’s like connecting two outputs to eachother, usually no problem, but there are modules for which it is a big nononono.
Every designer with half a brain will add input protection to his/her designs, but some just do not, and if you happen to have one of those you might be in trouble when you switch this module off while sending a voltage to its cv inputs...

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Re: Power switch for a single module

Post by Yes Powder » Tue Feb 23, 2021 7:38 am

This is a thing?
I leave individual cases unpowered with connections to them all the time, and have never had a problem.
Guess I'm lucky, or all my modules are designed around this. Certainly none have listed this as a danger in their manual. :despair:

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