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Micro Power AM Broadcast Transmitters: In this circuit, a 74HC14 hex Schmitt
trigger inverter is used as a square wave oscillator to drive a small signal
transistor in a Class C amplifier configuration. The oscillator frequency can be
either fixed by a crystal or made adjustable VFO with a capacitor/resistor
combination. |
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Micro Power FM Broadcasting Circuits: (added 8/03) |
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Micro Spy with FETs: (added 10/02) |
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Micro Spy with TTL: (added 10/02) |
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Micro Spy with USW: (added 10/02) |
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Miniature FM Radio Receiver using TDA7088: The electronic diagram of the
monophonic FM receiver made with TDA7088T is shown on Pic.4.12. If built with SMD
components it can be placed in a matchbox, altogether with two button-type batteries.
The operating principle of this device is given in the previous chapter. The only
thing new is a very simple audio amplifier made with BC547 transistor, which is loaded
by cheap 16-Ohm headphones. The telescopic antenna is used, as on Pic.4.8.
Small mishap of this receiver is that it has no indication of station tuning. This
problem can be solved by adding a small voltmeter in parallel to the BB909, whose
scale is graduated in MHz, as described in the Appendix. This solution is not
appropriate for the miniature receiver, since the voltmeter that has the scale that is
big enough takes too much space. It is in this case better using a manual tuning
instead of automatic. Such solution is given on Pic.4.13. The tuning is done via the
variable capacitor C with numbers written on its button, similar to that on Pic.3.11.
It is most simple to use numbers from 1 to 10. The variable capacitor is like the one
on Pic.4.8. Some experimenting is to be done with capacitances of Cx and Cy, in order
to cover the entire reception bandwidth, from 88 till 108 MHz.... (added
11/05) |
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Miniature FM Spy Mic: This spy mic works from single 1.5 volts AA type
battery cell. It is highly sensitive and has a range of 300 meters. You can use any HF
transistor with cut-off freq. >300 MHz for Q. Use electret mic. (added
11/05) |
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Miniature FM Transmitter #1: (added 10/02) |
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Miniature FM Transmitter #2: (added 10/02) |
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Miniature FM Transmitter #3: (added 10/02) |
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Miniature FM Transmitter: (Electronic circuit added 4/05) |
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Miniature FM Transmitters #4: (added 5/03) |
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Modem-Circuit Techniques Simplify Instrumentation Designs: AN-307-Analog
Device Application Notes (added 2/06) A commutating modem circuit, whether
an ICorpc-board, can serve as a building block form any measurement-system functions,
reducing noise and ensuring the integrity of transmitted data. |
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Modulation Monitor: very simple and useful circuit used to monitor on air
transmission of your low power amplitude modulated transmitter. . (Circuit added 9/04) |
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Modulator Draws just 5 mA at 27V: 06/05/97 EDN-Design Ideas / (added 2/06)
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Modulator's Design Cuts FPGA's Gate Count: 01/06/94 EDN-Design Ideas /
(Electronic Circuit diagram added 03/03) The pulse-width modulator (PWM) macro in Fig
1 requires only half as much logic as a conventional 2-counter design. With the help
of extra logic, a synchronous, loadable up/down counter can encode information in the
duty cycle of a constant-frequency, constant-amplitude signal.... |
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MPF102 FM Receiver: (added 9/02) |
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Nanosecond SCR Switch for Reliable High Current Pulse Generators and Modulators:
MicroNote 601 from Microsem (Circuit / schematic design added 6/06) |
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Nanosecond Width Pulse Generator Provides High Performance: 11/11/04
EDN-Design Ideas / (added 5/05) |
