The power amp board has remained unchanged since it was first published in 2002. It certainly isn’t broken, so there’s no reason to fix it. The photo below shows a fully assembled board (available as shown as M27). Using TIP35/36C transistors, the output stage is deliberately massive overkill. This ensures reliability under the most arduous [...]
This circuit is a stereo amplifier for a high sensitivity stereo parabolic microphone that able to used for listening to distant sounds. Typical parabolic microphones are monophonic, this unit has a stereo audio path that helps produce more realistic sounding audio. The Big-E can be used with headphones or as an audio source for a [...]
This is a really small alarm that could easily fit inside a pocket. However, I also demanded reliable operation, simple construction and very low power consumption. I started with CMOS logic gates, but was soon forced to abandon the concept after a few unsuccessful (and far too complicated) takes. Then I suddenly realized that a [...]
This Batteries Charger is intended for charging sealed lead-acid batteries with a solar panel in small and portable applications. The customary diode that prevents the battery from discharging through the solar panel has been replaced by a FET-comparator combination. The batteries charger will stop charging once a pre-set voltage (temperature compensated) has been reached, and [...]
This is a simple fire alarm circuit based on a LDR and lamp pair for sensing the fire. It uses a very simple approach to detecting smoke in the air. The alarm works by sensing the smoke produced during fire.The circuit produces an audible alarm when the fire breaks out with smoke. This probably isn’t [...]
Here’s a simple home alarm circuit is for those who are eager to know the concept of home security system. It consists of three 555 timers gets the input from a contact that could be connected to a motion detector or any momentary contact that monitors a certain process. Once the contact is momentarily closed, [...]
Circuit is Infrared gate sensor. It’s an infrared gate with two sensors planned to use in the wall in the way behind a door. It can be applied in a toilet to keep track of that someone is inside exceeding a certain amount of time. After that time elapsed, the circuit triggers the digital output [...]
