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Electronics => Projects, Designs, and Technical Stuff => Topic started by: ElectronSurf on March 29, 2023, 11:43:09 am

Title: Thumbnail fan controller
Post by: ElectronSurf on March 29, 2023, 11:43:09 am
I needed to add fan control capability for my 100W electronic load (https://www.eevblog.com/forum/projects/400v25a-100w-mini-dynamic-electronic-load/), It has to be small and easy to plug it in where the fan supply socket is.
So I came up with this design and thought I share with you, it's a simple and useful circuit to have.

I suggest to use a voltage reference to set the threshold voltage and also a flyback diode is needed, I think with a SMD MOSFET it can be even smaller than 25x18 mm.

Link to the simulator. (https://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWcMBMcUHYMGZIA4UA2ATmIxARQosgoFMBaMMAKGwVpQUJGJ6-548UZPBDZCkJAwAstMByjQZaPPHUaeAFToBbAA50ATgEMALgFcjdFkZAD7Q+9xAyZw+XBYBzZzzfCDjKEMiKQLADufrz+2FR8UCwAStEJQR4icuBUtLnQCCwmrnHikKEIYFS4ocTZImAaeSjNhGCShBwYCN2EOErNXDghYHwoEm3CDeq2xVVos+KEGc1edhVVZRQYPNX10wBmWzubHcehJWD5IBjhdqeLwvcBmdAYPiBP7h8uwaG5M-cEvcUE5PJFoiDhDISpD7DNoVRYQj7Cg-iivAATI6lcrbcB4qgYuj7EwWAA2Zhm6xRoWRzTRzA04IQeLAeOpbJ4twWCWRbVyFEk4SigNi8S58Iukge4GlnnCvgkk2lSvxXMSRT57MqapAkxyonU-QalEI2AUGDwxBkQ3IqGC+DA7kkVpQbOwoSm8HB9zitF9S3ELAAxtjdiydoH5IxJvkJJaSEsxtsZBAYHBWFEIzLkarhRQdfSC1ROYkonTUQsRjlmXjVQGPCwAB4fK3gUjXeZoKie4QAMRMADsWAB7PXga6uSAd+aoepKQhcFhAA)

(https://www.eevblog.com/forum/projects/thumbnail-fan-controller/?action=dlattach;attach=1749569;image)

- Don't judge my soldering, I was debugging this board!

(https://www.eevblog.com/forum/projects/thumbnail-fan-controller/?action=dlattach;attach=1749575;image)(https://www.eevblog.com/forum/projects/thumbnail-fan-controller/?action=dlattach;attach=1749593;image)

(https://www.eevblog.com/forum/projects/thumbnail-fan-controller/?action=dlattach;attach=1749581;image)

Title: Re: Thumbnail fan controller
Post by: mariush on March 29, 2023, 12:10:33 pm
Or you could get a fan with PWM feature and a 6-8 pin micro can use ADC to read the resistor and adjust the pwm signal as needed.

Maybe even a 555 could be repurposed instead of a micro.
Title: Re: Thumbnail fan controller
Post by: shapirus on March 29, 2023, 12:21:11 pm
What's the purpose of the upper op amp?
Title: Re: Thumbnail fan controller
Post by: ElectronSurf on March 29, 2023, 02:49:18 pm
Quote from: shapirus on March 29, 2023, 12:21:11 pm
What's the purpose of the upper op amp?
Turning off the fan at a set temperature.