Circuit Snippets

It is sometimes necessary to use a negative voltage in a construction that already has a positive drive voltage. For example, you might want a symmetrical drive voltage for an op-amp that otherwise only consists of logic circuits. Making a circuit that inverts the drive voltage can be a problem, especially in a battery derived equipment. In this circuit, T1 …

This circuit produces a dc voltage at the output that is almost twice the input voltage. For a 12V input the output is 22.1V @ 20mA. The voltage doubler is based on the charge-pump principle of operation. A charge pump is a kind of DC-to-DC converter that uses capacitors for energetic charge storage to raise or lower voltage. Charge-pump circuits …

PROBLEM DESCRIPTION I’m using the DS18S20 and DS18B20 in a energy control system. The 1-wire temperature sensors is connected on the same 1-wire bus. Just these two sensors are connected to the bus. The 1-wire is connected to a microcontroller i/o port. To pull down the 1-wire bus, an open drain pulldown transistor and a 1k resistor to +5V are …

In battery-operated devices that have removable batteries, you usually need to prevent the batteries being connected the wrong way to prevent damage to the electronics, ....