Transform noisy bench power supply to silent one

[r6502]

Hello all,

I could get an EA bench power supply 2x16V max 5A + 5V supply for a good price (PS 2316-050, the main 2 outputs could be run independent, parallel or in serial). The annoying thing with this device is, that it perfprms like a vacuum cleaner when turned on. The fans for cooling the power electronic, are running at full speed when turned on.

I had to improove this, so that the fans are running at high speed only, when a lot of power drawn from the external loads.

My goal to minimize the noise of the PS was to use only stocked components for this weekend project. I do not wont to use µC or special IC's (like microchip specil fan control chips like the TC647 or similar). I used what I found in my stock.

The design is based on a NE555 used as timing generator and an 74HC123, Dual retriggerable monostable multivibrator, to generate the the PWM for the fan and a few resitors  / capacitors and an 100k NTC acting as sensor for the temperature of the heat sink.

I think it is a really simple design - please have a look at the atacheed documents and leave your comments.

Have a nice week - Guido





 

[Clueless]

I had a 80x80mm PC case fan with temperature sensing speed control circuitry built in. The speed is based on the temperature sensed by a thermistor attached with ~6" leads. This was the perfect solution for me to quiet down an HP triple output supply. It looks like the same might work well for your application, if they are still available and if the maximum flow rate is high enough. Sorry that I don't remember the details on the brand of the fan or where I purchased it.

[dobsonr741]

I would not build it, rather buy. This guy did the same /w CN made small fan PWM controller: https://blog.donbowman.ca/2018/12/15/project-solitude-silence-the-power-supply/

[ledtester]

I found this blog post on adding a fan to the Topward 6603A helpful:

http://www.kerrywong.com/2012/12/08/adding-a-fan-controller-to-topward-6603a/

It's as simple comparator circuit which only turns on the fans when the main heatsink reaches a certain temp.

I think the main challenge is securing the temperature sensor to the heatsink. In the blog post a tape (perhaps with thermal adhesive) is used. I'd consider tapping a hole for a screw.