Published:2012/12/13 21:41:00 Author:muriel | Keyword: MF-HF, receive antenna, splitter
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Published:2012/12/13 21:38:00 Author:muriel | Keyword: Outdoor , MF and HF, Antenna
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Published:2012/12/13 21:34:00 Author:muriel | Keyword: one RF amp
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Published:2012/12/13 21:33:00 Author:muriel | Keyword: 10.0 MHz , crystal oscillator
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Published:2012/12/13 21:33:00 Author:muriel | Keyword: popcorn crystal filter
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Published:2012/12/13 21:32:00 Author:muriel | Keyword: 10MHz, crystalk bandpass, RF filter
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Published:2012/12/13 21:31:00 Author:muriel | Keyword: Feedback amplifiers
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Published:2012/12/13 21:30:00 Author:muriel | Keyword: L-Match, AM Detector
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Published:2012/12/13 21:30:00 Author:muriel | Keyword: 10 MHz, double tuned, RF band, pass filter
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Published:2012/12/13 21:29:00 Author:muriel | Keyword: Audio Amplifier
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Published:2012/12/13 21:28:00 Author:muriel | Keyword: VK4FUQ , AM detector
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Published:2012/12/13 21:27:00 Author:muriel | Keyword: XTal Filter, RF Amplifier
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Published:2012/12/13 21:26:00 Author:muriel | Keyword: Receiver Front End
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Published:2012/12/13 21:25:00 Author:muriel | Keyword: Experiments, JFET Biasing
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Published:2012/12/13 21:24:00 Author:muriel | Keyword: Antenna Tuner
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Published:2012/12/13 21:23:00 Author:muriel | Keyword: Antenna Tuner
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Published:2012/12/13 21:12:00 Author:muriel | Keyword: antenna tuner
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Published:2012/12/13 21:11:00 Author:muriel | Keyword: antenna tuner
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Published:2012/12/13 21:03:00 Author:muriel | Keyword: LED
Sequentially Off LED Pulser
This circuit uses a series of transistors with an RC pair to pulse a string of LEDs.
This the favorite LED experiment I performed this summer. This flasher circuit is different in that it turns off alternate LEDs for about 1 second in sequence. When you connect this circuit to the 9 volt battery, all of the transistors are usually placed in saturation and therefore all the LEDs are on. Closing the switch on the base terminal of Q1 for a moment initiates the correct pulse sequence. The pulse initiates in Q1 which turns off the LED connected to the Q1 collector for about 1 second. When Q1 turns back on (goes into saturation), Q2 turns off. When Q2 turns back on then Q3 turns off and so on. The circuit is a closed loop and many more stages may be added.
You can experiment with different base resistor and coupling capacitor values to vary the speed of the LED string or to create a sense of randomness by varying each transistor's RC stage separately. This is a fun circuit! (View)
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Published:2012/12/13 21:02:00 Author:muriel | Keyword: 6 LED, FLASHER
A schematic to allow the 4017 decade counter to sequentially flash 6 LEDS left-right-left-right-etc. Connect your favorite square wave oscillator to pin 14. I built 4 of these using various oscillators and LED colors. You might consider using lower DC voltages and if so, may adjust the 1K current limiting resistor by using ohm's law. The 10 small signal diodes may be any appropriate type including the 1N914 or 1N4148. None of my 4 projects exceeded 6 mA peak current draw, so battery life is excellent. I increased the 1K resistor to 1K5 in my 4th project as I found the LED's that I used too bright. (View)
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