Free electronic circuit design and schematic diagram
In the simplest form, current to voltage converter can be implemented as simple as one resistor, since a voltage is developed when an electrical current flow against a resistance. The problem is that the resistance always affect the current by decreasing the current flow, and the current to voltage conversion is not accurate. In some cases, the resistor that convert […]
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Integration is one of basic signal processing that can be done in analog domain. Using operational amplifier (op-amp), integration operation can be done with very simple circuit with very high accuracy. Here is the schematic diagram of an integrator circuit: The resistor R2 should have the same value with R1 since R2 is employed to minimize the offset error due […]
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The temperature of a quartz crystal for oscillator should to be kept constant to operate at very stable frequency. This oven temperature controller is suitable for such purpose. Here is the schematic diagram of the temperature control circuit: Although this circuit is small and simple, the design use a PWM output to preserve the efficiency. The circuit uses LM335 temperature […]
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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 any unused gates to ground or to […]
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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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