Free Circuit Diagram

TDA2003 is my favorite audio amplifier integrated circuit chip in 10 Watt class. All you need is just adding few passive components and your amplifier will be ready. You can even amplify ultrasonic range if you wish to abuse its usage, just to convince you that this chip is more than enough to handle any [...]

Graphic equalizer is a filter which it’s overal frequency response can be adjusted easily by sliding the potentiometer knob, and the potentiometer’s knob positions will naturally mimic the frequency response of the filter, and this is very user friendly. Many methods have been developed by electronic engineers to make audio equalizer, such as Baxandall’s [...]

This audio power amplifier circuit is simple and robust, and use discrete component available on many electronic part stores. The final transistors use 2N3055 and MJE2055. Here is the circuit’s schematic diagram: The MJE2055 is an npn transistor, but the configuration with TIP42A make the whole combination of TIP42A and MJE2055 are seen [...]

This PWM motor control circuit provides many controls for DC motor. You can control the DC motor to rotate forward, reverse, or break until it stops. Here is the schematic diagram of the circuit: The circuit uses MOSFETS bridge to drive the motor, controlled by some logic gates and small bipolar transistors. The [...]

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 [...]

Unlike the 10-band graphic equalizer in our previous circuit that use a gyrator circuit, this 3-band graphic equalizer circuit uses Baxandall topology, similar with the Baxandall tone control but with additional mid frequency control. The figure below shows the schematic diagram of the circuit. The operational amplifier employ an LF351 IC chip, but [...]