Published:2011/7/31 22:00:00 Author:Ecco | Keyword: Computer motherboard
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Published:2011/7/31 21:59:00 Author:Ecco | Keyword: Computer motherboard
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Published:2011/7/31 22:08:00 Author:Ecco | Keyword: CMOS, 555 , equivalent function box
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Published:2011/7/31 22:10:00 Author:Ecco | Keyword: Color ring display, foreign capacitor
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Published:2011/7/31 22:11:00 Author:Ecco | Keyword: digital power amplifier
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Published:2011/7/31 22:10:00 Author:Ecco | Keyword: 5.1ch amplifier
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Published:2009/6/28 21:45:00 Author:Jessie
This circuit may be used where a high current is required with a low ripple voltage (such as in a high powered class AB amplifier when high quality reproduction is necessary). Q1, Q2, and R2 may be regarded as a power darlington transistor. ZD1 and R1 provide a reference voltage at the base of Q1. ZD1 should be chosen thus: ZD1 = Vout-1.2. C2 can be chosen for the degree of smoothness as its value is effectively multiplied by the combined gains of Q1/Q2, if 100 μF is chosen for C2, assuming minimum hfe for Q1 and Q2, C = 100 x 15(Q1) x 25(Q2) = 37,000 μF. (View)
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Published:2009/6/28 21:43:00 Author:Jessie
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Published:2009/6/28 21:43:00 Author:Jessie
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Published:2009/6/28 21:42:00 Author:Jessie
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Published:2009/6/28 21:41:00 Author:Jessie
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Published:2009/6/28 21:41:00 Author:Jessie
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Published:2009/6/28 21:40:00 Author:Jessie
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Published:2009/6/28 21:39:00 Author:Jessie
Circuit NotesA bar column of LEDs is arranged so that as the audio signal level increases, more LEDs in the column light up. The LEDs are arranged vertically in 6 dB steps. A fast response time and a one second decay time give an accurate response to transients and a low flicker decay characteristic. On each of the op amps inverting inputs is a dc reference voltage, which increases in 6 dB steps. All noninverting inputs are tied together and connected to the positive peak envelope ofthe audio signal.hus, as this envelope exceeds a particular voltage reference, the op amp output goes high and the LED lights up. Also, all the LEDs below this are illuminated. (View)
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Published:2009/6/28 21:38:00 Author:Jessie
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Published:2009/6/28 21:37:00 Author:Jessie
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Published:2009/6/28 21:36:00 Author:Jessie
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Published:2009/6/28 21:36:00 Author:Jessie
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Published:2009/6/28 21:21:00 Author:May
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Published:2009/6/28 21:21:00 Author:May
Uses basic oscillator consisting ofQ2 and Q3 arranged as collectorcoupled astable MVBR. Power is taken from collector of Q1 which acts as switch for Q2 and Q3. With S1 closed and S2 open, oscillator operates. Closing S2 saturatesQ1 and stops oscillator. When used as headlight reminder for negativeground car, B1 is omitted and power for oscillator is taken from dashboard panel lights since they come on simultaneously with either parking lights or headlights. If ignition key is turned on, al saturates and disables Q2-Q3. With ig-nition off but lights on, Q1 is cut off and oscillator receives power. Audio output may be connected directly to high side of voice coil of car radio loudspeaker without affecting operation of radio. Almost any NPN transistors can be used. Changing values of R4 and R5 changesfre-quency of reminder tone.-H. F. Batie, Versatile Audio Oscillator, Ham Radio, Jan. 1976, p 72-74. (View)
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