Understanding small voltage regulaters - constant 12V DC output - variable DC input

[Yoda]

Yoda Keith, I'd have to ask questions on the waterproof one you linked. I know with some controllers, you have to adjust output based on input voltage. If you use an auto step up / down automatic then it may be a bit more reliable output. https://www.pololu.com/product/2577 came up when I did a quick look around. The deal with building robots and stuff so they have some neat stuff.

Joseph
You just warped my mind tonight. Good grief it must have artificial intelligence. Something to consider but it seems some assembly required. Not real a problem, I just would need to find a good box to put it in. I appreciate the input. I am learning a lot here, which is a good thing to kick out some of the old gray cells.
Thanks for the help
Keith

[Scott'n'Wendy]

Scott Scott'n'Wendy I am aware of the noise. The stock fan is 44 to 48db

I was referring to the noise generated by a PWM controller, not the fan. I have installed/repaired and programs dozens of them. They all emit a high pitch frequency whine. But they were all higher than 12volt devices.
I was just suggesting you check if there is any appreciable noise generated by the controllers you are looking at.

[TedS]

Use a simple rheostat, potentiometer.

[Yoda]

I was referring to the noise generated by a PWM controller, not the fan. I have installed/repaired and programs dozens of them. They all emit a high pitch frequency whine. But they were all higher than 12volt devices.
I was just suggesting you check if there is any appreciable noise generated by the controllers you are looking at.

DOH!!! Now I understand. In reviewing the Notcua NA-FC1 I ran across no mention of noise, but I will dig deeper and email the folks down under. If I understand correctly in generating the pulses there is a corresponding frequency noise? Thanks for the heads up.

TedS Ill look into that, but not sure if that will work for PWM 4 wire fan - maybe the 3 wire coolerguys one.

On thing I have learned is technology has passed me buy. I understand simple rheostats, potentiometers - they just vary the voltage. This new pulse width modulation is interesting. Instead of varying voltage to control fan speed, the power is sent in pulses to vary the fan speed. I hope I got that right.

[TedS]

Yoda , yes, pwm varies time on/time off.

It wouldn't matter 2, 3, or 4 wire. They all have one 12+ and one gnd -. You just would not connect the third or third and fourth wires.

[gbkims]

I had bought the DC-DC Buck Boost a couple of weeks ago that looks same as the 1st one linked by Keith. It is for a cellular router's DC input.
Tobsun 36W DC-DC Converter 12V 3Amax - It dropped off Amazon's page already..


I hooked up a couple of older Brushless DC (BLDC) Fans that are just 2 wire w/o speed adjustment to a 12V SLA battery used in home UPSes.
The fans are NMB 3610KL-04W-B50-D00 12VDC, 92mm x 92mm x 25mm
- https://www.digikey.com/en/products/...B50-D00/776446


2 fans running direct connection to the battery, 12.71V DC and 2.6mV noise signal measured at the battery:


2 fans running from the DC-DC Buck Boost's Output, 12.12V DC at the fans, 6.3mV noise signal measured at the battery.

[gbkims]

Couple more photos. I pulled apart a RV Frig's fan to peak at the circuit board.

[Yoda]

I had bought the DC-DC Buck Boost a couple of weeks ago that looks same as the 1st one linked by Keith. It is for a cellular router's DC input.
Tobsun 36W DC-DC Converter 12V 3Amax - It dropped off Amazon's page already..


I hooked up a couple of older Brushless DC (BLDC) Fans that are just 2 wire w/o speed adjustment to a 12V SLA battery used in home UPSes.
The fans are NMB 3610KL-04W-B50-D00 12VDC, 92mm x 92mm x 25mm
- https://www.digikey.com/en/products/...B50-D00/776446


2 fans running direct connection to the battery, 12.71V DC and 2.6mV noise signal measured at the battery:


2 fans running from the DC-DC Buck Boost's Output, 12.12V DC at the fans, 6.3mV noise signal measured at the battery.

Ill pretend like I fully understand this - but it appears wiring direct from the battery is much better as with the dc-dc buck is 3 times louder. How does the 6.3mV noise signal convert to something I might hear?

Thanks Gene

Keith

[rvoelker]

I think there are three different 'noises' that have come up
Noise of the fan spinning - blades cutting through air
Audible noise emitted from the device - a whine or buzz potentially emitted from the converter device itself (Scott'n'Wendy)
Power Line Noise - ripple or noise signal generated by the device that could appear on the DC Bus(dbkims). [Which might be noticed in the audio output of your stereo]

[gbkims]

Ill pretend like I fully understand this - but it appears wiring direct from the battery is much better as with the dc-dc buck is 3 times louder. How does the 6.3mV noise signal convert to something I might hear?

Thanks Gene

Keith

I don't hear the signal made by the DC-DC converter as it's above normal hearing range.. I only hear the the fans, but my ears are old with tinnitus so the sound might be masked.

It's the electrical noise that's of interest to me.
Checked the output of the DC-DC Buck Boost, it's puts out more noise to the fans.
Set the scope to 100mV scale since the output signal is a lot higher voltage, versus 20mV scale on I used on the input side of the DC-DC.
So I don't think I'd use it for an electronic device's DC input.

DC-DC Buck Boost to 2 BLDC Fans:


Adjusted the time/division scale to view the signal..


Thanks Keith for getting me motivated to hook up this DC-DC Buck Boost and testing it.
It'll be headed back to Amazon.

[TedS]

After a little research, I found the frequencies are 20kHz and higher. Upwards of 420kHz. The upper end of hearing and beyond.

[Yoda]

So to bring this to a conclusion - I do not need or want a small DC-DC buck and just go with direct fused 12V connection and the Noctua PWM NA-FC1 fan speed controller. I did a full search on the NA-FC1 and there are no noise issues - in fact no issues at all.

Am I on the right page after this great discussion?

Thanks Keith