This transmitter can be used for transmitter hunts, for remote key finding, or for radio telemetry in model rockets. It can be tuned to the two meter band or other VHF bands by charging Cl and Ll. 11 is four turns of #20 enameled wire airwound, 0.25 inch in diameter (use a drill bit), 0.2 inch long, centertapped. The antenna can be 18 inches of any type of wire. IC2 functions as an audio oscillator that is turned on and off by IC1 about once per second. ..
At this circuit the SSM2044 IC is used, a 4 pole voltage controlled filter designed for electronic music applications. On-chip voltage control of resonance allows direct and easy interfacing with programmers and controllers. The IC features extended control range, low noise, and high control rejection. The filter can also be used as a low distortion sinewave oscillator...
Have you ever wondered how many different colors can illuminate a LED? One, two or maybe three? Constructing this simple circuit, you will find it much more. The key component in this design is a dual LED. One such accessory includes two inside the 'slices' of different diode LED, that each of them produces a different color (usually green and red). For the drive requires three pins, a common cathode and two separate roots. In this way each of the two integrated diodes can.....
A shows a typical LTC 1148 surface-mount, application providing 5 V at 2 A from an input voltage of 5.5 V to 13.5 V. The operating efficiency, shown in B, peaks at 97% and exceeds 90% from 10 mA to 2 A with a 10-V input. Ql and Q2 comprise the main switch and synchronous switch, respectively, and inductor current is measured via the voltage drop across the current shunt. /vgENSE is the key component used to set the output, current capability according to the formula/QUT.....
A sidetone oscillator is a special audio astable multivibrator. Keying is accomplished oscillator that is turned on and off with the by applying a positive dc potential, developed transmitter. The oscillator is rf-driven and bat- from the rf signal, to the reset terminal of the tery operated..
The low-pass Sallen-Key filter is staple for designers because it contains few components (A). By redesigning the filter,..
The circuit uses a four-bit latch (Ul). What makes the circuit sequential is that the set input of the first bit latch is tied..
IR radiation from LED2 (modulated by a 1-kHz wave) is keyed by Ul, and Ql is radiated. Reflected IR energy i..
Apply a signal to each differential amplifier input pair. When the gate voltage is changed from one extreme to the ot..
The ATMEL, with family AVR, was consolidated in the field of microcontrollers. The microcontrollers are, providing fast core and a variety of peripherals. These features continue to occupy the attention of engineers and earn their preference. The developer will see, it accepts all models of the family of AVR. It is an excellent tool that stands out for its high performance and simplicity in handling. To develop, based on the record of AVR, the AVRDONGLE.PDF. If someone.....
Most of you will certainly already installed on your computer one of the many software tools move freely from hand to hand and is suitable for programming the PIC 16C84. One of the most popular of this kind is the RIR02 of Silicon Studios. The circuit described below, is perhaps the simplest PIC programmer that can work seamlessly with the program RIR02. This guide allows RIR02 communication with the programmer, through the parallel port (Centronics). ..
SI is external key switch. The alarm allows a 0- to 45-s delay after SI is operated before the circuit is armed. During this per..
This circuit is useful for monitoring slow logic pulses as a keying monitor or digital clock alarm. The Schmitt trigger is connected as an oscillator...
Adding a diode, a resistor, and a capacitor to the SAW (surface-acoustic-wave) oscillator allows you to use the oscillator in FSK (frequency-shift-keying) applications. Dl, Rl, and Cl form a simple diode switch in which Dl shunts Cl to ground. When the digital FSK input to Rl is low, Dl is off, and the small junction capacitance of Dl couples Cl to ground. A high FSK signai causes current to flow through Rl and Dl. Dl "s dynamic impedance is small when it is in forward.....
This encoder uses a single contact per key keyboard and provides all other switching function electronically. The diode between terminals 8 and 15 prevents the output going more than 1 volt negative with respect to the negative supply V-..
This switch uses four CD4013 BE dual flip-flops, an inverter, and an optoisolator to drive a triac. The circuit can switch 25-A ac load current. A standard 4x3 telephone keyboard is used to enter a 6-digit code. In case of a wrong code, a signal is available to activate ah alarm...
By vocalizing the numbers and symbols of its~eypad, the phone provides an audible confirmation that is useful to the blind. The serial-interface, 2 K-byte x 8-bit ROM (!C4) stores programmed sequences of instructions that are executed by the speech-processor chip IC2-manufactured by the General Instrument Corp. When you depress a key, tone-dialing chip ICl issues the corresponding number of pulses at its DP output. ..
This circuit shows the TP5700 directly interfacing to a low-voltage DTMF generator. VREGt supplies the necessary 2-V minimum bias to enable the TP5380 to sense key closures and pull its mute output high. VREGt then switches to a 3-V regulated output to sustain the tone dialer during tone generation. The TP5700 DTMF input incorporates the necessary load resistor to V-and provides gain, plus AGC action, to compensate for loop length. ..
Here is a simple method of series connection into the telephone set suitable for PABX or short line applications. When the telephone handset is lifted, Cl is charged via D1 to (Vz1 -0.7) V and DF320 power on reset occurs. When the first keyed digit is recognized, Ml goes to logic 1, muting the telephone network by switching on the low on resistance JFET Ql, and maximizing the line-loop current for impulsing. Impulsing occurs through DP switching Q2, and hence Q3 turns.....
The darkroom timer/controller uses few external components: a display, a digit driver, keyboard, and output switching devices. A 4-digit common-cathode LED display is desirable for dark room environments. The time base is provided by shaping up the 50/60 Hz ac line. A DPDT switch (Si) is used to select a resolution of or 1 seconds and to simultaneously move the decimal point..
Operational Amplifiers
Computer Systems
Oscilloscopes
Transmitters & Receivers
Sensors & Detectors
ANSI Standards
Low Frequency Amplifiers
Power Amplifiers
Number Systems
Regulated Power Supplies
Analogue Filters
Digital Gates
