Free electronic circuit design and schematic diagram
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 motor voltage can be 10-20 Volts and […]
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This circuit is conventional “Pierce” type oscillator that uses a JFET. The circuit uses fundamental mode crystals. It has decent performance and reliability if we use a low noise JFET. The feedback is controlled by the C1 Capacitance from drain to ground. Adjusting the frequency can be done by adjusting a shunt capacitance C2 across the crystal. The crystal works […]
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By detecting a voltage drop in resistor connected in series with the battery, we can measure the current flowing in or out of the battery. A simple differential amplifier do that, but we need both positive supply and negative supply to sense the current in both direction, the current when charging and discharging the battery. We can use a single […]
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This circuit is a simple crystal oscillator that can be operated in overtone mode. Overtone mode permit the operation at higher frequency than specified by the crystal. The circuit uses a grounded base amplifier configuration, and place the crystal as a series resonator. The transistor Q1 is biased in the active region as an amplifier. L1C1 is a resonant circuit […]
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Sine wave oscillator can be implemented using Wien-Bridge oscillator like in our previous sine wave oscillator circuit, but now we present another method of generating sine wave signal. Using phase shifter, we can build a simple sine wave generator, as shown in the schematic diagram below: Sine wave oscillator using phase shifter has lower distortion than Wien-Bridge oscillator, coupled with […]
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The LM4610 uses DC signal to control the tone (bass/treble), volume, and balance circuit. The advantages of using DC control is that you can use a mono potentiometer to control both channel, even you can use a DC signal generated from a DAC, so you can control the sound using microcontroller or microprocessor. This circuit can applied for car radio, […]
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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 external components. Here is the […]
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