MiSTer FPGA Forum

venalaine wrote: ↑Wed Mar 10, 2021 10:22 am It would be nice to hear what some hardware oriented developers in Mister community think about the subject. And of course there are some other FPGA guys (Krikzz & Kevtris etc...) who surely know how this goes but maybe they don't want to say anything related to Mister.

I think it's as overblown as the fan fears. You asked.

I have an in line power switch on the primary. I just took a lamp cord and used that. The baseless fears of voltage drops on the secondary are a non-issue, then.

I've never seen this particular brand of baseless fear before, best would be to delete the thread and forget about it entirely.

ash2fpga wrote: ↑Wed Mar 10, 2021 3:48 pm Not the de10, but the Cyclone V datasheet has power specs: https://www.intel.com/content/dam/www/p ... _51002.pdf

Yeah, I found that but I don’t think they’re desperately helpful since they use regulated voltages. But if I’m reading it right (I might not be!) then the minimum voltage is negative? Yeah, I really don’t know what to make of that.

C-R-T wrote: ↑Wed Mar 10, 2021 8:04 pm I've never seen this particular brand of baseless fear before, best would be to delete the thread and forget about it entirely.

This is sort of my point. I think a user will get fed up with stability problems if they drop too much voltage long before they damage anything. But who knows. Presumably only Terasic and they don’t give any useful info that I can see.

On my mister I use a 5V meanwell power supply: https://www.amazon.com/MEAN-WELL-GST25A ... B01D0Z8PLW

Then I have a power switch on the AC power cord. It is similar to this one but not an extension/adapter: https://www.amazon.com/outstanding-Powe ... B08NP3L9KB

This eliminates needing to switch the 5V.

dot-bob wrote: ↑Wed Mar 10, 2021 10:17 pm On my mister I use a 5V meanwell power supply: https://www.amazon.com/MEAN-WELL-GST25A ... B01D0Z8PLW

Then I have a power switch on the AC power cord. It is similar to this one but not an extension/adapter: https://www.amazon.com/outstanding-Powe ... B08NP3L9KB

This eliminates needing to switch the 5V.

I'm using this Mean Well adapter (European version though) and can highly recommend it: https://www.amazon.com/MEAN-WELL-SGA40U ... 07CSP8H7P/

rhester72 wrote: ↑Wed Mar 10, 2021 6:33 pm

venalaine wrote: ↑Wed Mar 10, 2021 10:22 am It would be nice to hear what some hardware oriented developers in Mister community think about the subject. And of course there are some other FPGA guys (Krikzz & Kevtris etc...) who surely know how this goes but maybe they don't want to say anything related to Mister.

I think it's as overblown as the fan fears. You asked.

fan fears——> do you mean people fearing failure earlier because of not providing a decent cooling solution?

I dont want to seem arrogant or somethin, just asking cause I never heard the term before.

I had a suspect inline for about a year. Finally ditched it, and got a quality psu (Triad). I paired it with a smart outlet so I can just toggle the MiSTer with an app now

max1602 wrote: ↑Thu Mar 11, 2021 1:33 pm

rhester72 wrote: ↑Wed Mar 10, 2021 6:33 pm I think it's as overblown as the fan fears. You asked.

fan fears——> do you mean people fearing failure earlier because of not providing a decent cooling solution?

I dont want to seem arrogant or somethin, just asking cause I never heard the term before.

Yes, sorry - I realize I could have worded that better.

rhester72 wrote: ↑Thu Mar 11, 2021 2:07 pm

max1602 wrote: ↑Thu Mar 11, 2021 1:33 pm

rhester72 wrote: ↑Wed Mar 10, 2021 6:33 pm I think it's as overblown as the fan fears. You asked.

fan fears——> do you mean people fearing failure earlier because of not providing a decent cooling solution?

I dont want to seem arrogant or somethin, just asking cause I never heard the term before.

Yes, sorry - I realize I could have worded that better.

Thanks.

It's just at the moment I am in exactly that situation.
I am unsure how much fan-power mister needs...

- Does the board need to be cooled with a fan even if I don't use a case?

- Can I use a fan w 12v on 5v even if the fan only provides a small amount of blow then?

- Do you know a thread in this forum where fans on mister has been discussed a lot?

It's difficult for me to find enough info on the topic.

I have fan fears, I admit

Low voltage should not damage your mister. What it will most likely do is make things unreliable and reset. Most of the devices run at 3.3V or lower. The design uses a buck regulator to drop 5V input to 3.3v. Regulators usually need a little headroom so it will probably need an input voltage 0.5-1.5V over the 3.3V to regulate properly.

What will most likely happen is your USB devices will drop out as they won't get the 5V power they need to operate. The DE-10 nano also has a voltage supervisor that if the 3.3v gets too low it will assert reset and hold the chips in reset until voltage returns.

I think people get confused about the term undervolting which can cause damage due to overclocking. People often undervolt to reduce the amount of heat produced at a given clock rate then this allows you to clock memory and a microprocessor faster to improve performance which in turn produces more heat. In this instance the hardware crashes and is not held in a reset state. Chips go into latch up and you get can get damaging shoot through.

dot-bob wrote: ↑Fri Mar 12, 2021 1:40 am I think people get confused about the term undervolting which can cause damage due to overclocking.

Sure some do.
But most that have a basic understanding in electricity probably do not.

Take that buck converter for example.
If you run a lower voltage trough that it means it will draw more amps to get enough power (=watt) to run everything on the output side since those components still need the exact same power.
And if you run higher amps trough something it will generate more heat and therefore have the potential of causing damage to the components in the buck converter if the voltage drop is not planned when it was buildt or lower end/cheaper components is used.

venalaine wrote: ↑Tue Mar 09, 2021 6:58 am So then I assume it is safe to use switches, for example, sold by misterfpga.co.uk.

This is no slur on them cos they are great, but my inline switch from misterfpga.co.uk stops my keyboard working. I didn't realise it was a thing until I just read this but I always assumed it was sucking some extra power away and stopped using it and chucked it.

I assumed I was unlucky. Looks more of a thing than I realised.

RascalUK wrote: ↑Sun Mar 21, 2021 7:26 pm

venalaine wrote: ↑Tue Mar 09, 2021 6:58 am So then I assume it is safe to use switches, for example, sold by misterfpga.co.uk.

I assumed I was unlucky. Looks more of a thing than I realised.

It's certainly not normal behavior for the inline switches I supply, I suspect your switch was faulty, if you drop me a message via the contact form on my website with your order number I will have a replacement sent out to you.

Mate, you are a superstar. I don't expect a replacement as I never complained about it. I'll send you a message with the order number though, it was over a year back, just found the email.