Voltage-Controlled Low-Pass Filter with LM13600 OTA
Below is a circuit that demonstrates one use of an OTA using an LM13600. Take a note that the strange symbol stand for OTA. In this circuit, negative feedback is employed which is low-pass filter whose corner frequency can be electrically adjusted. We can a filter that would tune from 2700 Hz to 9000 Hz …[Read More]
Varactor Test (Experiment) Circuit
A varactor is also known as a varicap or a variable capacitance diode. An electrically controllable capacitance is provided by this varactor which can be used in tuned circuits. What makes it’s advantageous in many application are the small size and inexpensive. If compared to a manually controlled variable capacitor, this varactor has disadvantages such …[Read More]
This a Sallen and Key Lowpass Filter circuit. This circuit is a second-order active filter. This circuit can be changed to highpass filter by interchanging capacitors and resistors. This circuit is featured with buffer. The buffer of this circuit is op-amp which configured in inverting configuration. This circuit is stable, since this circuit has positive …[Read More]
Twin-T Notch Filter
This is a Twin-T Notch Filter circuit. This circuit is a filter that can remove a certain frequency band. This is a passive filter that uses two filters in parallel, high-pass and low-pass. The high-pass filter is lower one and the low-pass filter is the upper one. This filter has a problem with the input …[Read More]
Complement Phase Inverter with Single Transistor
This is a complement phase inverter circuit. Sometimes this circuit called a paraphase amplifier circuit. This circuit has two output signals that is have sufficient “headroom” because this circuit is biased. The transistor will be saturated when the collector decreases, the emitter voltage increases and set the limit. Here is the circuit: This circuit can …[Read More]
Voltage Multiplier with Diodes and Capacitors
This is a voltage multiplier circuit. This circuit uses a doubler principle to multiply the voltage. This circuit has some advantages like low current supply, attractive high voltage that is needed for photomultipliers and cathode-ray tubes. Besides that, this circuit is inexpensive. This principle is also used in the Cockroft-Walton accelerator for charged particles the …[Read More]
555 – 741 IC Voltage To Frequency Converter
This voltage to frequency converter (VFC) circuit uses 555 IC and 741 op-amp as the main components. Up to 20kHz oscillation can be produced by this circuit. Here is the schematic diagram: The zero adjustment is used to adjust the lowest frequency, short the input to ground and adjust this pot to obtain the lowest …[Read More]
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