Monday, 7 January 2019

Making Ruideng DPH5005 power supply case fan silent

I use Ruideng DPH5005 as a bench power supply and it is quite good for what I need, the only problem I have with it - 5V high speed fan of the original power supply case which runs always, regardless of load/temperature, making a lot of noise.

DPH5005 board has it's own small fan which kicks in only when power supply is overloaded, so probably I could disconnect the case fan completely or connect it to the heatsink fan, but I find no fun in doing so.

There are a couple of suggestions on the Internet how to deal with the noise of the fan - connect it in series of diodes to lover running voltage or to use Normally Open bi-metal thermal switch to turn on the fan at about +45 C.

I liked the latter, but decided to combine it with the first one to limit the driving voltage with a diode. And I had a nice and proven project for that: Madis Kaal tiny_pwm for ATtimy85 microcontroller.
Using pure PWM did not work with this fan - to run the fan stable at the lower speed I had to use quite low PWM frequency with clock divider 128, which was creating extra noise, diminishing the purpose of the project.

As power supply provides 5V, we can use bump-on-the-wire approach to control the fan. Modified schematics looks like this:

Sunday, 7 October 2018

Making Bose QC 25 USB friendly

I've been using Bose QuietComfort 25 for a couple of years now. They are great for watching movies on long transatlantic flights, but their miniature on-the-wire microphone and 3mm audio jack makes them unusable for long transatlantic Skype calls. Adding USB capability sounded like a good idea, and it wasn't hard at all with my new Prusa i3 MK3 printer.

For Skype I've been using Plantronics 626 for almost 8 years and finally ear pads started to disintegrate. Instead of soursing a new ear pards for this discontinued headset I decided to used Bose QC 25 as a replacement :)

First make a model in blender3d:


 Then print:

Making black visible on black

Yesterday I tried to print using black PLA on Prusa i3 MK3 and found that black PLA on black PEI is very hard to see :) But just a week ago I got my UV LED flashlight and it did the trick - turned black PEI heatbed coating to greenish and black PLA to blueish colour:


So no problems to control the first layer :)

Sunday, 16 September 2018

Making Darkroom FIlm Hanging Clips

I do not have a darkroom, so I dry my 135 film in the shower hanging it to the shower frame using a few pieces of wire and paper clips. Or at least I used to until now. All these wires and paper clips are history now, thanks to my new shiny 3D printer.


Friday, 14 September 2018

Puting dials on feet

The first version of the stand for my salvaged dials functional but boring (see the previous post).
So here comes the new version which puts the dials on feet, literally.


Sunday, 9 September 2018

Salvaging temperature and humidity dials

A few month ago my wall clock with temperature and humidity dials feel down from the wall and broke apart.

For the clock mechanism it probably was a good move (I would throw it out of window someday anyway, so loud it was). But temperature and humidity dials were quite useful, so I decided to keep them and reuse some day. And with my new and shiny Prusa i3 MK3 printer this day just came yesterday.