Electronics > Microcontrollers

ATTiny 1604 fan module, please criticize

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Hi folks,

Here is my project - ATtiny 1604 based fan controller - it can use 2/3/4 pin fans and control them based on temperature - https://gitlab.com/rglory/tinyfan . Please criticize.


Looks very close to what I'm looking to build but it's a bit more complex by the looks of it. Would it be possible to modify this circuit to only run 1x PWM fan, controlled by 10K Thermistor with an ability to define fan speed at temperatures stretching from 40 to 100 degrees C while keeping the PCB as small as possible?

The board is quite small actually, you can use it without soldering extra components you do not need if you want. PCB can be smaller without them, but that requires redesign/retesting.

For example if you already have 5V you do not need U2 and components around it. If only need 10K thermistor you can replace R3 with 10K and not to solder R2 R10 and D3. If you only need PWM control you do not need U3 optocouple and Q2 mosfet etc.

But for such simple module I've seen some on ebay made in China, they quite cheap I beleive.

I think the schematic could use some comments and (more) net names.

It looks like you've got a buck regulator on there, which is fine, but I'd definitely want to show my workings (how resistor values are derived) so that I'll understand the design when I come back to it (regardless of whether someone else wants to review)

That's just my style though, I get confused if I don't try to explain myself to myself.

General comments

Values for R8 and R9 are very unusual, you probably want to find more common values (e.g. E6 resistors)

Sensors J1, J2 - probably needs to explain what kind of sensor goes on there. It's also not absolutely clear why R1 exists (current limit I guess)

LED resistors (R5,R6) - the LEDs might be uncomfortably bright / have short life as they will be running close to their rated current, consider 1.5k for a still visible indicator with better longevity. Obviously this depends what LEDs you use and other things (such as if the device is intended for outdoor use).

You might want a comment on the range of VDC, and note what voltage ratings the various capacitors need (if VDC is much greater than 5V)

Capacitor C3 it is unclear why this needs to be an electrolytic, you might be able to use a ceramic. 16uF is an unusual value looks like it's come out of a calculator / automated design tool, consider putting a more standard value (e.g. 22uf)


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