Free electronic circuit design and schematic diagram
This driver circuit is not only boost the voltage to enable a single battery cell to power two red LEDs or one white LED, but also regulate the current so the light will be constant until the battery runs out its power. The main component of this single cell LED driver is transistors and ferrite core transformer. You can visit […]
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The benefit of LED is longer lifetime than incandescent lamp, and even higher efficiency in latest LED technology. LED is also very compact, but unfortunately it needs higher voltage to operate. A single cell battery (1.5v) or rechargeable cell (1.2V) cannot be used to power LED directly. We have to use a DC-to-DC step-up converter to enable single cell operation […]
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Gyrators are synthetic inductors, which are often used to form bandpass filters. As shown in the two examples here, the active buffering device can be a transistor or op-amp. This type of bandpass filter is commonly used in graphic equalizers and other frequency control circuits such as tone controls. In the gyrator frequency calculator here, enter the values of R1, […]
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Typical LED indicator consist of resistor (R2) and LED, connected in series with a switch. When the switch is closing or opening, a glitch noise may occur at the supply line. To avoid this noise, R2 and C1 are added to the indicator circuit and value of R1 is adjusted. Very slightly delay is provided by the R2-C1 circuit which […]
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The R1/C1 network makes a low pass filter when the wiper is at the grounded end of the tone pot, and there is a treble cut. The C1 cap bypasses R2 when the wiper is adjusted so that it is at the top end of the pot and it creates a treble boost. The 100k output volume and the 100k […]
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Variation of the famous Baxandall circuit is shown in the passive circuit in figure 1. Smoothly increasing +- 6 dB/octave slope of boost or cut is the feature of this circuit. Although the “shelves” are outside the audible range with these component values, the bass and treble filters have a shelving response. The threshold and shelving frequencies is predicted by […]
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This schematic diagram below shows a Digitally Controlled Dual Polarity Amplifier circuit. The circuit (a) can give a means of amplifying a signal either in non inverting and inverting mode. When S2 is off and S1 is on, the noninverting input of the op amp is fed by the signal. The circuit behaves as a regular inverting amplifier, When switch […]
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