Dilshan R Jayakody’s Web Log

Recently I got an interest to experiment with NOAA weather satellite reception techniques. As a first thing, I did search on the internet for a suitable antenna for NOAA satellite frequencies (137.100 MHz - 137.9125 MHz). After examining a couple of designs, I decided to build a Turnstile antenna which is designed by Ivo Brugnera I6IBE . Due to the COVID19 lock-down, I build this antenna using parts that are already available in my inventory. Originally, I build this antenna on a wood-stick, and later I changed it to a stable setup as shown below. Assembled antenna for 137 MHz NOAA weather satellite receptions. Following materials and components are used for the above construction: - Two 8cm × 8cm × 6cm waterproof ABS project box. - 54cm long, ⌀ 21mm PVC tube, which is reinforced by inserting water resistivity wood stick. - 8mm thread roads. - M8 nuts and M8 flat washers. - 50Ω and 75Ω coaxial cables. - PL259 male and female connectors. Before constructing this ant...

This is an experimental stepper motor driver for Celestron CG-4 German equatorial mounts . This unit is functionally equivalent to the Celestron dual-axis motor driver , and we developed it as a replacement unit for the original Celestron driver. The prototype circuit board of the motor controller unit. The core component of this motor driver is PIC16F88 8-bit MCU. This MCU is responsible for driving two motors and scanning the user inputs. As an original unit, this system also got a clock driver for the right ascension (RA) axis. This system uses two L293 motor drivers to drive the right ascension (RA) axis and declination (DEC) axis motors. This unit is designed to work with 6V bipolar stepper motors, which include in the telescope mount. The LM350 voltage regulator is used to maintain power to both stepper motors. Internal view of the prototype enclosure. This replacement motor drive provides all the functionalities of the original unit, which including manu...