Free Circuit Diagram

RS485 interface gives some more benefits compared to RS232: simplicity and the robustness for long distance transfer. RS485 is simpler because it uses only two wire (or a single pair) to carry out the data in bidirectional manner, using RS232, we need 3 wires at minimum to carry the data bidirectionally. RS485 cable length can [...]

Using only transistors as the active components, we can build a simple and low cost TTL-to-RS232 level converter. It uses only two transistors as the active components. Here is the schematic diagram of the converter: /caption] You can use any small signal transistor for this RS232 converter circuit. You can see [...]

Many new computers now only has USB port, and this serial to USB adapter might be the only help for old devices that provides only RS232/COM Port. This serial adapter uses FT232 USB-RS232  converter IC from FTDI (Future Technology Devices International).  The main features of this USB serial adapter chip are: 384 [...]

Using MAX232 integrated circuit, you can build a TTL-to-RS232 level converter that totally comply with RS232 electrical specification. The IC generate the higher positive and negative voltage (+10 and -10 Volts)  from TTL power supply (5V DC) using switched capacitor. The switching circuitry is provided inside the chip, so you need only few caps for [...]

High precision analog front end (signal conditioner) presented here can be used for portable ECG equipment that requires single-supply operation. There are two kind of amplifiers on the circuit diagram, the instrumentation amplifier INA326 and the dual precision amplifier OPA2335. Both operate from a single 5V supply and apply autozeroing techniques. Autozeroing techniques will keep [...]

The schematic diagram below show a complete barometric pressure signal conditioner that operates from a single 1.5V battery. We can get the best accuracy and stability if we use bonded strain gauge and capacitive-based transducer,  but they are expensive.  This design introduce a new type of semiconductor transducer that achieves 0.01″ Hg (inches of mercury) [...]