Fan Speed Controller

I have some cool pictures of fan speed controllers installed in the kitchen as part of the ventilation system. There is a ventilation hood on the ceiling for extracting smells from the kitchen. Ventilation fan is located outside and controller is located on kitchen wall.






Some previous posts about this fan controller can be found here (normal version) and here (IR controlled version).

Another example of installation is to ventilate the welding workshop. Poison fumes from welding process are taken outside by speed regulated fan:


Preamplifier with PGA2311

I proudly present my DIY HiFi preamplifier! It is based around Hi End audio chip PGA2311 manufactured by Burr-Brown. Chip I'm using is A-grade version with even better THD+N than standard U-grade (0.0002% THD+N at 1kHz vs. 0.0004% THD+N at 1kHz).

Other parts in the preamp I designed myself: triple power supply - positive and negative analog and digital power supply are completely separated (unlike in some cheap Chinese versions). Power supply circuit is copied from Lehmann Black Cube Linear design, which is much praised.

There are 3 inputs routed with quality Takamisawa signal relays. Control board utilizes AVR controller, encoder volume control with LED bargraph for volume level vizualization. Unit can be controller with IR remote controller.

It looks nice in the company with AKG 701 earphones and Lehmann BCL amplifier (and sounds even nicer!):


One look inside reveals internal design:


Speed control of circulator pumps

I made speed control for my Grundfos circulator pump used for central heating system.
Control circuit is made of AVR/Arduino controller which, through PWM signal, controls SSR output.
SSR used for this application is G3MB-202P-DC5, which have zero cross function. Zero cross is a must if you want to control induction motor. Control is done with mains voltage pulse burst. Burst frequency is 8 Hz, but it can be higher.

Standard water circulating pumps with induction motor and no control electronics can be speed controlled this way.

Schematics and board can be found here. Notice that SSR used have resistor in series with diode, so additional resistor between AVR pin and SSR is not needed. SSR can be driven directly from AVR output pin.

Video demonstration:

CNC Laser Cutter

All documentation needed for making these upgrades can be downloaded here.

During summer I was thinking of a way to cut plasticized labels, the ones used for my devices. Idea was to use laser. Reading the internet I found that 0,3W Blue ray laser is enough to cut paper, so decided to buy Chinese 2.5W laser CNC and give it a try. It turned out it's a quite quality device, but it needed some additional work on it to become fully usable. I will start by showing cut made with it.

Snowflakes made from colored paper:






Some "roses" I draw in CAD:
This was intended purpose: plasticized labels for my devices:




It took me some time to find good working software, since BenBox which supplier reccomends is just a crap. First I draw cutting routes in CAD and save it as .dxf. Then dxf2gcode is used to generate gcode. In the end universal gcode sender is used to send cutting code to machine. Once it's calibrated everything works quite well.



This is how my heavily modified 2.5W laser cutter looks like:



There is vacuum plate for clamping labels to surface. Vacuum plate uses 6 PWM fans for making underpressure, and these fans are controlled with this small unit:



Printed labels need some positioning system to make cuts aligned with prints. For this purpose small laser pointer is added together with main laser head. This makes two points surface alignment system.
Also, near laser head there is small centrifugal fan, which is essential for blowing off fumes which disturbe laser beam and reduce it's power making it insufficient for cutting.



Video presentation:

Regulator brzine ventilatora s daljinskim

Nakon iskazanog interesa za osnovni regulator, razvio sam varijantu s mogučnošću daljinske kontrole. Ručna kontrola zakretanjem enkodera i dalje ostaje.

Daljinska kontrola je zgodna kada se regulacija nalazi visoko i daleko od dohvata ruke, kada je smještena uz sami ventilator koji se nalazi na stropu prostorije. I sam koristim sličan sistem za odsisavanje lemnih para - ventilator je visoko u kutu ispod stropa.

Konstruirao sam i poseban daljinski s četiri tipke - taman koliko je potrebno. Daljinskim se može povećati brzina (+), smanjiti (-), trenutačno podići na punu brzinu (100%) i trenutačno ugasiti (0%).






Iznutra uređaj ima terminale za spajanje mrežnog napona 230 VAC i izlaz za ventilator. Izazni trijak podržava struje do 2A, što odgovara snazi ventilatora do cca. 500W.
Spajanje je krajnje jednostavno:





Testiranje uređaja na odsisnom ventilatoru pogledajte na videu:


Diferencijalni termostat s regulacijom brzine

Diferencijalni termostat je jednostavan uređaj. Osnovna funkcija mu je upravljanje radom pumpe na temelju temperaturne razlike. Do sada sam napravio nekoliko varijanti (1, 2, 3) i sve su bile ON/OFF princip.

U želji da unaprijedim uređaj nastao je diferencijalni termostat s regulacijom brzine.
Osnovna razlika je da se brzina pumpe mijenja u ovisnosti o temperaturnoj razlici kolektor - akumulacija. Veća razlika temperature znači veću brzinu pumpe i obratno.

Prednosti regulacije brzine u odnosu na ON/OFF regulaciju su:
- pumpa radi kontinuirano što znači tiši rad,
- nema naglih skokova u temperaturama kolektora i akumulacije,
- više topline se izvlači iz kolektora jer se postižu manje temperaturne razlike,
- na kraju dana toplina ne ostaje "zarobljena" u kolektorima.

Dijagram regulacije brzine pumpe u ovisnosti o temperaturnoj razlici:


Pogledajte simulaciju rada s objašnjenjima svih parametara:


Regulator brzine vrtnje ventilatora

Kada osnivate radionicu u kojoj ćete intezivno zavarivati potreban vam je ventilacijski sustav. Pare koje se stvaraju pri varenju treba izbaciti iz zatvorenog prostora.

Prijatelj uređuje bravarsku radionicu, a ja sam obećao izraditi regulator brzine odsisnog ventilatora. Ovaj uređaj sam napravio s lakoćom i brzo. Sav hardver je bio pri ruci, viškovi od drugih projekata, a par linija koda koji u 8 kB kontroleru zauzima 12% sam napisao u roku jednog popodneva.

Ventilator kojim se upravlja je snage nešto manje od 100W. Upravljački element je elektronički relej koji podržava struju do 2A. Radi na principu sjeckanja napona s detektorom prolaska kroz nulu. Frekvencija sjeckanja je 8 Hz.

Evo kako to izgleda sve zajedno i o kojem se ventilatoru radi.



Iznutrice sam već spomenuo ali sada malo detaljnije. ATmega8 kontroler je zadužen za enkoder i led traku. Kontroler također generira pravokutni napon koji služi za upravljanje  elektroničkim relejem. Specifičnost ovog uređaja je napajanje koje je izvedeno pomoću HLK-PM01 ispravljača. Ovaj ispravljač je izuzetno kompaktan, montira se na pločicu i rješava vas potrebe za glomaznim i nespretnim vanjskim adapterom. Evo slike iznutra:





Kada pogledate film ispod shvatit ćete koliko je ventilator snažan dok puše i da mu definitivno treba regulacija. Kontroler ima praktičnu funkciju da pritiskom enkodera brzina trenutno skače na 100%, a ponovnim pritiskom se vraća na vrijednost prije skoka.

Video: