After the random timer based on an Attiny24 I have build a larger version of the random countdown timer. The Attiny24 had a single channel and two potentiometers. In this countdown timer the number of outputs have been increased from 1 to 8. The potentiometers have been replaced by a 2×16 HD44780 LCD screen and a rotary encoder.
With this random countdown timer circuit you can turn on and off 8 outputs. The outputs are, while randomly turned on and off, still grouped together meaning that as a group that at the beginning and half way the countdown timer cycle they are all on or off at the same time.
With this circuit you can simulate people turning on and off internal house lighting in a street on a model railroad track. Read on and see it in action.
What is a time server? A time server gets its time from a reference time source. That source can be a another time server, a local time source such as a rubidium or cesium atomic clock. In this post I make an USB GPS receiver for a Linux time server using cheap available components. After assembling the GPS module I give instructions on how to configure the Linux NTP daemon to use this module. The GPS receiver gets its time signal from the GPS satellite network. Its longtime time drift is about 0 seconds. This is possible because the GPS time signals are constantly adjusted to keep very accurate time needed for navigation.
This howto shows you the schematic of a popular TDA2030A amplifier DIY kit which is sold on eBay and other places.
After ordering the kit on eBay (search for “TDA2030A Audio Power Amplifier DIY Kit”) I received a version 1.0 PCB made by XY HI-FI with components and a short Chinese manual on what was needed to solder the kit in stereo mode (OCL) or in mono mode (BTL or bridge). Continue reading
Buying electronic parts on eBay is not as simple as it seems. Most of the time you get what you ordered, sometimes not. Here is a list of my own survival rules I discovered over the past few years.