Free electronic circuit design and schematic diagram
Diode for alternating current is a trigger diode which conducts current only after the DIAC reach the breakdown voltage. The breakdown voltage of DIAC is 30 V. It has construction like an open base NPN transistor. The DIAC can be used in many application such as motor speed controls and light dimmers circuit. Figure below shows the DIAC block construction, […]
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The diagram below shows us a simple block construction of an SCR (upper left) and its schematic diagram (upper right). The lower diagram shows us the operation of a PNPN device can best visualized as a specially coupled pair of transistor. When a proper gate signal is applied to the base of the NPN transistor, the connections between the two […]
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A full-wave rectifier circuit that provides the absolute value of input signals up to ±2.5 V even though operated from a single 5 V supply is shown in the schematic diagram below. The amplifier acts as a unity-gain inverter for negative inputs. The op amp output is forced by positive signal to ground. The 1N914 diode becomes reversed-biased and the […]
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We can use tone/frequency detector (decoder) to detect the presence of a signal with a certain tone. The output of the circuit will be active if the signal is the same tone with the tone of a series of internal oscillator. LM567 is one of decoder that we can use. The LM567 and LM567C are general purpose tone decoders. Both […]
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The Vc1 increases linearly when the pull-up resistor RA in the monostable circuit is replaced with constant current source, generating a linear ramp. The linear ramp generating circuit and the generated linear ramp waveforms illustration is shown in figures below. Current source is created by PNP transistor Q1 and resistor R1, R2, and Re. Ic= (Vcc-Ve)/Re Ve= Vbe + (R2/(R1+R2))Vcc […]
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While keeping the oscillator frequency relatively stable, this 555 based PWM controller features almost 0% to 100% pulse width regulation using the 100k variable resistor. To give a frequency range from about 170Hz to 200Hz , the frequency is dependent on the 100k pot and 100n. You can see the charging and discharging of the 100n cap is done through […]
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Anti-log or exponential generation is simply a matter of rearranging the logarithmic circuitry. The circuit diagram below shows the circuitry of the log converted to generate an exponential output from a linear input. The emitter of Q2 in proportion to the input voltage is driven by amplifier A1 in conjunction with transistor Q1. The collector current of Q2 varies exponentially […]
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