To monitor the filling of a bath, a water tank, or a swimming pool, or to warn when a gully is overflowing, here’s a very simple water level detector built around a CD4011 CMOS quad Gates IC... Read more
A shortwave audion receiver using only two transistors and a single 1.5 V battery — that must be the ideal entry level into shortwave receiver technology. Just add an active PC loudspeaker f... Read more
Although ready-made twilight switches for exterior lights are available in every home improvement shop, any self-respecting electronics enthusiast would rather put together something from a... Read more
Overall, electromechanical scooter starter solenoids are cheap enough — but the downside is that they’re not very reliable. The contact resistance increases over time, the coil can be open-c... Read more
This LED flasher is made up of just five components and is an ideal circuit for novices to experiment with. Operation of the circuit is quite easy to understand. With a battery connected to... Read more
The ring oscillator comprises a number of inverting transistor amplifier stages connected in series, in which the output of the final stage is connected to the input of the first stage. You... Read more
When the environment becomes dark, the resistance of the LDR increases. An increase in resistance causes the voltage to rise on this element. The increase of the voltage in the LDR transmits... Read more
This circuit is inspired by an amplifier published in the ’60s that produced 8 watts a channel into 8 Ω and was based on AD161 and AD162 germanium (not ‘geranium’) power transistors. These,... Read more
The TDA7052A is a readily available amplifier chip (Farnell # 526198) that has a DC controlled volume input. Here, the IC is used as the variable gain amplifier in a guitar compressor, so th... Read more
In some circumstances, it may be necessary to select LEDs with closely matched characteristics. This design makes the job a whole lot easier. It uses two tracking current sources to allow th... Read more
