The author encountered a problem with a microcontroller system in which the +5-V supply voltage did not decay to 0 V sufficiently quickly after being switched off. A certain residual voltage... Read more
Lots of consumer electronic equipment like TV sets, VCRs, CD and DVD players employs infrared remote control. In some cases, it is desirable to extend the range of the available control and... Read more
a voltage supervisor chip to produce a clean reset pulse to the processor whenever a ‘brown-out’ condition of the power supply is detected. More complex designs employing multiple power supp... Read more
This circuit was designed to protect a computer monitor from overheating. It is recommended to attach this circuit to power users’ monitors! Most computer monitors of the CRT type fail owing... Read more
This circuit may be used to replace the single current limiting resistor often found in dirt cheap battery chargers. The alternative shown here will eventually pay off because you no longer... Read more
The general assumption is that white LEDs operate at a voltage of 3.6 V and a current of 20 mA, which is about right. Lithium-Ion cells coincidentally have a voltage of exactly 3.6 V, which... Read more
Communication over the IrDA port uses a relatively complex protocol but its possible to send a single character using just a few components. In many cases, this will be sufficient to control... Read more
This circuit arose from the need to couple the outputs of two CDROM drives to the input of a single sound card. Simply ‘stacking’ the connectors is possible but not particularly elegant, and... Read more
In many small battery powered apparatus it is common to have an LED act as a combined indicator for ‘power-on’ and ‘battery state’. The most commonly seen circuit for this is shown in Figure... Read more
All simple constant-current sources generally operate on the same principle: a current is allowed to flow through a resistance and some sort of regulator is used to try to hold the voltage a... Read more
