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18 ~ 60MHz third harmonic oscillator

Published:2013/3/15 3:07:00 Author:Ecco | Keyword: 18 ~ 60MHz, third harmonic, oscillator

18 ~ 60MHz third harmonic oscillator is shown as figure. (View)

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15 ~ 65MHz third harmonic oscillator

Published:2013/3/15 2:59:00 Author:Ecco | Keyword: 15 ~ 65MHz, third harmonic oscillator

15 ~ 65MHz third harmonic oscillator is shown as figure. (View)

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LED on -off time controlled oscillator

Published:2013/3/15 3:06:00 Author:Ecco | Keyword: LED , on -off time, controlled oscillator

LED on -off time controlled oscillator is shown as figure. (View)

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Dual astable multivibrator using 556

Published:2013/3/14 1:46:00 Author:Ecco | Keyword: Dual astable multivibrator

Dual astable multivibrator using 556 is shown as figure. (View)

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The square wave generating circuit using op amp

Published:2013/3/14 1:41:00 Author:Ecco | Keyword: square wave generating, op amp

The square wave generating circuit using op amp is shown as figure. (View)

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Programmable astable multivibrator

Published:2013/3/14 1:43:00 Author:Ecco | Keyword: Programmable astable multivibrator

Programmable astable multivibrator is shown as figure. (View)

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The switching harmonic crystal oscillator

Published:2013/3/7 2:34:00 Author:Ecco | Keyword: switching, harmonic , crystal oscillator

The switching harmonic crystal oscillator is shown as figure. (View)

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Voltage controlled multivibrator circuit

Published:2013/3/14 1:38:00 Author:Ecco | Keyword: Voltage controlled multivibrator

Voltage controlled multivibrator circuit is shown as figure. (View)

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The voltage controlled TTL symmetrical multivibrator

Published:2013/3/14 1:45:00 Author:Ecco | Keyword: voltage controlled, TTL symmetrical multivibrator

The voltage controlled TTL symmetrical multivibrator is shown as figure. (View)

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Oscillator circuit using LM3900

Published:2013/3/14 1:51:00 Author:Ecco | Keyword: Oscillator

Oscillator circuit using LM3900 is shown as figure. (View)

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The bistable multivibrator circuit diagram

Published:2013/3/14 1:52:00 Author:Ecco | Keyword: Bistable multivibrator

The bistable multivibrator circuit diagram
Bistable multivibrator circuit diagram is shown as figure. (View)

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100kHz self-excited multivibrator

Published:2013/3/7 2:38:00 Author:Ecco | Keyword: 100kHz , self-excited multivibrator

100kHz self-excited multivibrator is shown as figure. (View)

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Pulse forming circuit with integral circuit

Published:2013/3/12 3:32:00 Author:Ecco | Keyword: Pulse forming , integral circuit

Pulse forming circuit with integral circuit is shown as figure. (View)

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1Hz clock signal oscillator

Published:2013/3/12 3:27:00 Author:Ecco | Keyword: 1Hz , clock signal oscillator

1Hz clock signal oscillator is shown as figure. (View)

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0.5 seconds tone burst circuit

Published:2013/3/12 3:29:00 Author:Ecco | Keyword: 0.5 seconds , tone burst circuit

0.5 seconds tone burst circuit is shown as figure. (View)

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Smooth Tone Clickless CW Sidetone Generator

Published:2013/3/7 3:08:00 Author:Ecco | Keyword: Smooth Tone, Clickless, CW Sidetone Generator

Smooth Tone Clickless CW Sidetone Generator
This circuit is essentially a minimal version of an analog music synthesizer that is hard-wired for the purpose of making morse code tones. The oscillator section produces a fixed frequency triangle wave on LM324 pin 14, that is fed into a low pass filter to get a sine wave on LM324 pin 8. A triangle wave can be thought of as a series of sine waves with decreasing amplitudes as the frequency increases. The low pass filter simply removes the upper harmonics and passes the fundamental sine wave frequency through. The sine wave is sent to a voltage controlled amplifier made from three 2N3904 transistors. The upper two 2N3904 transistors should be a matched-gain pair in order to minimize thumping sounds. The VCA is modulated with a keying waveform to produce the resulting modulated waveform. The keying waveform is generated by smoothing out the square wave keyed signal on the 4N32 emitter with the 220K/220K/20n (.02uF) capacitor/resistor low pass filter on the base of the lower transistor. The two 220K resistors in series with the 4N35 output transistor act as a voltage divider, this causes the the keying envelope to swing between 0V and 6V, which is a good range for controlling the VCA. Keying of the circuit is performed either by the manual key input, or via the keyer input, which can be used to connect the circut to a morse code keying chip. To use the keying input, an active low open collector driver should be used. The audio signal comes out of LM324 pin 7, it connects to a 10K volume potentiometer and an attenuator made with two resistors. The attenuated audio is then fed to the LM386 audio amplifier. (View)