Free Circuit Diagram

What we can do with a stereo voltage-controlled volume control? There so many things, we can control our audio using a DAC which is controlled by a microcontroller, or we can use mono potentiometer with RC filter to minimize the scratched sound produced by a dirty potentiometer (I see this method in one of SONY [...]

Current loop interface has been widely used in industrial environment because it’s robustness. Noise resistance and fail detection capability  made it suitable for long distant transmission in harsh environment. This circuit provide current loop transmitter for temperature sensor. Here is the circuit’s schematic diagram:

The temperature measurement is done by LM35 temperature sensor chip. You can [...]

If you send a DC voltage signal to carry the information for a long distance, then the signal will suffer attenuation  with unpredictable characteristic introduced by the medium, for example the cable resistance that vary with temperature changes. If you carry the information with frequency, not a DC voltage level, then the frequency will be [...]

If you have a digital voltmeter, or any voltmeter with millivolt resolution and high input impedance, then you can use this temperature-to-voltage adapter circuit to measure room temperature. Here is the circuit’s schematic diagram:

Note that the voltage output of this circuit is floating, not referenced to ground. You have to use separate supply [...]

Operational amplifiers for tone control circuit application require high slew rate, wide bandwidth, high input impedance, and high output current characteristics, and CA3140 is suitable for this purpose. Look at the following tone control circuit’s schematic diagram for the design.

The tone control circuit in the figure above use a very popular Baxandall tone control configuration [...]