Dilshan R Jayakody’s Web Log

In this post, we introduce simple and flexible, regulated low voltage power supply unit. This power supply has provision for 4 outputs such as 1.5V, 1.8V, 2.5V and 3.3V. We mainly build this low voltage power supply unit to test (and power-up) low voltage MCUs, CPLDs, and radio receivers. For this power supply, we choose 1.8V, 2.5V and 3.3V to get it compatible with most of the LVTTL/LVCMOS devices. Other than that, we include 1.5V because there are several analog ICs are available for that voltage level. This power supply unit is based on LM1117/AMS1117 voltage regulator series and for this design, we use AMS1117-1.5, AMS111-1.8, AMS1117-2.5, and AMS1117-3.3 fixed voltage regulators. Except to above regulators, this board can be used with AMS1117-2.85 and AMS1117-5.0 regulators. Internal view of the low voltage power supply unit. In our prototype, we use center-tapped 6V (1A) step down transformer with this power supply unit. All the wiring diagrams to transformer and rotary...

This is quick (and final) post regarding our Mullard 3-3 audio amplifier project. In the last few months, we got several e-mails regarding this project and most of the people are asking for modified schematic related to this project . The schematic of our amplifier is available to download in here . Please note that this schematic is heavily based on the original Mullard 3-3 amplifier design and the main component which we replace in that original schematic is its tube base power supply unit. As a final step of this project, we construct a wooden enclosure for that amplifier and attached it to 10 inch (8Ω) full range speaker. High-resolution photographs of our amplifier are available in here . Final view of Mullard 3-3 audio power amplifier As a conclusion, this Mullard 3-3 audio power amplifier is a high-quality low power tube amplifier with minimum complexity. We really impressed with its audio quality and overall performance.

Star test is the most recommended method to test and collimate telescopes . To do a " star test " we need to aim and track telescope with real star and most of the times this is quite difficult to do because of the fast movement of stars and bad sky conditions. Another problem with the real star is air turbulence and some times this effect may lead to false conclusions. However artificial star is an excellent alternative for " real star test " and in this post, we introduce easy to build "artificial star unit" to test and collimate telescopes. This unit is based on commonly available electronic components and it can operate with a 9V battery. At the time of writing this unit can build around LKR 1000.00 (Approximately 7.00 - 8.00 USD). In this given design, we use NE555 timer IC to generate PWM output to LED and this allows us to control the intensity of the artificial star. In our prototype we use high-bright 3mm white LED as our light source. Apa...