Wednesday, August 5, 2015

100MHz frequency counter

Couple of weeks ago I purchased from eBay one of these amazingly cheap an useful modules with MAX7219 LED driver and 8 digit LED display. It is ideal for frequency counter project. The problem was the absence of library for PIC microcontrolers. Luckily, I found a great library for Arduino and I reworked it to be compatible with PIC. The schematic of the frequency counter is actually almost the same as the previous . It uses PIC16F628A microcontroller with external 32.768kHz watch crystal attached to Timer1 to generate 1 second time base. Measured signal is fed to pin3 (RA4) which is counted by Timer0.

Sunday, August 2, 2015

Simple and small temperature fan controll

I published this schematic long ago in this article: Adjustable power supply and since then I made some improvements in PCB to make the board as small as possible. The idea is to be easy to attach the whole board to the heat sink which we want to monitor. The board is only 27mm x 27mm.

Thursday, May 14, 2015

Thermal controlled fans

Since many years I am fan of quiet computing, but I also like power computers and videocards because I like do play games from time to time. That's why I have tried number of different solutions to control the fans in my computer.

Thursday, April 16, 2015

Audio oscillator with frequency counter 2

My last project is not completely new. In fact, the oscillator is made from the same schematic as in one of my previous projects and only the frequency counter is made with different schematic.


Wednesday, August 20, 2014

Frequency counter with PIC16F628A

Some time ago I made an audio oscillator with frequency counter which worked very well, but I sold it, and now I am making a new one. The oscillator itself will be mostly the same and when I finish the whole project there will be a separate article. Here I will show the frequency counter module I made for the project.

Wednesday, June 11, 2014

LED VU Meter with LM3916

This was finished months ago and just now I had time to finish the article. LM3916 is a dedicated IC for VU LED meter.  Unlike LM3915 which have 3dB step between voltage levels, the LM3916 have nonlinear steps: -20, -10, -7, -5, -3, -1, 0, +1, +2, +3db, just like old school analog VU meters. I saw in YouTube an interesting commercial LED VU meter, which imitates the needle movement in analog VU meters and I thought I can make a similar one. All I needed I found in the datasheet of LM3916.