Free electronic circuit design and schematic diagram
This is a simple sawtooth generator circuit. The advantages of this circuit are low cost and produces an auxiliary square wave at the same frequency. This circuit can be used to sweep the frequency of another generator. Here is the circuit : A voltage-controlled current source is formed by IC1 with R1 and Q1. The C1 is discharged by current […]
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This circuit is a simple buzzer circuit and it called novel buzzer. It only uses a relay in series with a small audio transformer and speaker. The relay will operate via the transformer primary and closed relay contact, when the switch is pressed. The normally closed contact will open as soon as the relay operates, removing power from the relay, […]
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This circuit generates a square-wave which is useful as a clock signal or AC drive for the excitation of sensors. this article presents a square-wave oscillator. This circuit requires no external components unless the bypass capacitor. Figure below shows the circuit, the output frequency and a scope shot of the output waveform. AC-powered subsystems or a square-wave (clock) generator for […]
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In some PLL application, sometimes we need to provide lock indication when the PLL is in locked state. The simplest one is binary indication, 0 or 1 to correspond with lock/unlock condition. This condition should be easy to be presented with a LED lamp. The schematic diagram shows a lock-detection scheme for the CD4046B. The PLL system uses phase comparator […]
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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: Two Schottky diodes is employed to […]
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A PLL system can be used to build a frequency-selective frequency multiplier by inserting a frequency divider inside the feedback path between the VCO output and the phase error detector input. Here is the schematic diagram of a low-frequency synthesizer with a programmable three decades divider circuit. The frequency-divider modulus N can vary from 3 to 999, in single steps […]
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Bubba oscillator is another example of phase shift oscillator. The Bubba oscillator takes the advantage of quad op-amp package to get 45 degree phase shift for each section. The result is excellent d(phase)/d(t) to get very low frequency drift. Here is the schematic diagram of the circuit: Each RC section give 45 degree phase shift. A low impedance quadrature output […]
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