Free Circuit Diagram

This PWM  circuit needs only two inverter gates, so you can build up to 3 independent PWM circuit using only one IC chip, since there are at keast 6 inverter gates in one IC package. Here is the schematic diagram of the circuit: Please remember that you should connect any input pins of [...]

For battery operated devices, this class D amplifier is suitable because its high efficiency (85%) helps extend the battery life. In the internal circuitry, a boost converter  with over 90% efficiency is provided to step-up the voltage supply, and need only one external inductor as the additional component for this function. When driving 8 ohm [...]

You might be familiar with passive crossover network installed inside your speaker box, consist of inductors and capacitors. The problem with passive crossover network is that they dissipate the audio power, so it’s not environmentally friendly, contributing a little disaster of global warming.  Moreover, the capacitor and the inductor in the passive crossover network contribute [...]

Op-amps has been widely used in low frequency oscillator (frequency <= 100kHz), but we can actually use it for high frequency crystal oscillator as long as we have an op-amp with the proper bandwidth. An excellent gain stages can be implemented using LT1190 and LT1191 op-amps. Here is the schematic diagram of the circuit: [...]

A constant-current/constant-voltage linear charger for single-cell lithium-ion (li-ion) can be constructed using only a tiny battery charger controller chip EUP8054 and a few passive components. This tiny integrated circuit chip is suitable for various portable devices. This controller chip is also compatible with USB power specification, ideal for charging the battery when the device is [...]

Frequency meter can be used in speed sensor, tachometer, or any measurement of repetitive signals. This frequency to voltage converter (FVC) can be used to turn your analog or digital voltmeter into a tachometer. The circuit’s schematic diagram is shown below. The circuit consist of three blocks. The first block is a squarer, [...]