The electromagnetic ring launcher is comprised of.four subcircuits: a clock circuit (built around U5, a 555 oscillator/timer configured for astable operation), a count-down/display circuit (built around U3), a 74190 synchronous up/down counter with BCD outputs that is configured for countdown operation; U4, a ECG8368 BCD-to-7-segment latch/decoder/display driver; and DISP1, a common-cathode seven-segment display), a trigger circuit (comprised of U6), an MOC3010.....
The oscillator section uses three sections of a 7400 quad NAND gate integrated circuit. The 1-MHz signal from the oscillator is fed into a 7 490 decade counter configured to divide by ten, providing the 100kHz signal. To obtain the 50 and 25kHz outputs, the 100-kHz signal is further divided by 7473 dual J-K flip-flop. The first half of the 74 73 divides the 100-kHz signal by two, yielding the 50 kHz signal. The second half of the 7473 again divides by two, giving the.....
This circuit will check a crystal for activity. Two sections of a 7400 act as an oscillator and its output is rectified and drives an npn transistor that switches an LED (Fig. A)...
A circuit using one 7400 TTL10 can use crystals of the fundamental type, from 1 to about 13 MHz. Output is rich in harmonics,..
This circuit should be useful for interfacing phone projects to the telephone line. ..
A SN7400 quartz crystal and a resistor provide a square-wave output of approximately 3.5 V. ..
Two NAND gates are used for the oscillator, and two as the control. If the two-tone speed needs to be altered, the 220 µ capacitors can be changed Oarger for slower operation). If the frequency of the oscillator is to be changed, the 0.2 and 0.1 /iF capacitors can be varied and the value of Rl can be increased. To change frequency range between the two notes, alter the 1.5 k (1,500) resistor= ..
This simple window detector uses only half of a 7400 quad NAND gate plus four resistors, chosen so that the voltage at point A exc.,eds the voltage at point B for any input voltage. With no input applied or when VIN is at ground, the output of gate Gl is one; hence G2"s output is also one. As the input voltage increases, VA rises faster than JOB. ..
The circuit uses two gates of a 7400 IC cross-connected to form an astable multivibrator driven by the 1-pulse per second output of the digital clock IC. The hee-haw circuit has a low frequency astable modulator added to make a self-contained European-type siren. Tone and rate can be varied as desired by changing capacitor values...
This is the latest version of the Improved Infrared Receiver with Status LED which can control any desktop PC with an ordinary remote control. The project comes along with a small PCB in order to save space. It connects to the serial port as stated in the schematic and uses the freeware Girder (www.girder.nl) software together with Igor?s Plugin (www.cesko.host.sk/girderplugin.htm) to send commands to the PC. The potential uses of this device are countless (control MP3.....
# This version uses a double sided PCB. Dimensions are approximately the same as the original version. # Removed the second push button switch and components for the RS232 serial interface. # Added 22K resistor between MCLR input and Vdd. This eliminates the need for a jumper on the ICSP header in normal operation. (If you use a 12F683 you can omit this resistor as well since it has an internal pull-up) ..
This complete high quality, low noise 5-BAND GRAPHIC EQUALIZER circuit is based around Monolithic Linear integrated circuit LA3600 manufactured by SANYO. This circuit is very easy to build and has good Quality. You can use it with Portable component stereos, tape-recorders, radio-cassette recorders, car stereos etc... It is On-chip one operational amplifier. 5-band graphic equalizer for one channel can be formed easily by externally connecting capacitors and variable.....
U1a operates as a low-noise microphone preamp. Its gain is only about 3.9 because the high output impedance of the drain of the FET inside the electret microphone causes U1a?s effective input resistor to be about 12.2K. C2 has a fairly high value in order to pass very low frequency (about 20 to 30Hz) heartbeat sounds.? U1b operates as a low-noise Sallen and Key, Butterworth low-pass-filter with a cutoff frequency of about 103Hz. R7 and R8 provide a gain of about 1.6 and.....
This is a high quality power supply with a continuously variable stabilised output adjustable at any value between 0 and 30VDC. The circuit also incorporates an electronic output current limiter that effectively controls the output current from a few milliamperes (2 mA) to the maximum output of three amperes that the circuit can deliver. This feature makes this power supply indispensable in the experimenters laboratory as it is possible to limit the current to the typical.....
This nifty sound level meter is a perfect one chip replacement for the standard analog meters. It is completely solid state and will never wear out. The whole circuit is based on the LM3915 audio level IC and uses only a few external components. This circuit can also be integrated into audio amp projects...
This PSU has been especially designed for current-hungry ham radio transceivers. It delivers safely around 20Amps at 13.8V. For lower currents, a separate current limiting output, capable of 15ma up to a total of 20A has been added. Let us see what we have got here. The power transformer should be capable to deliver at least 25A at 17.5 to 20V. The lower the voltage, the lower power dissipation. The rectified current will be ?ironed? by the C1, whose capacity should not be.....
The object is to get the cell voltage high enough for the sulphate to dissolve without boiling or melting the battery. This is achieved by applying higher voltage for shorter periods and let the battery rest for a while. The pulses on short range is about 0.5s on / 3s off and the long pulse range is 1.4s on / 2s off. These times can vary depending on component tolerances. Start on long pulse and if you discover ?boiling? (more than with normal charging) in the electrolyte.....
This circuitry offers some features that are highly desirable when building a QRP (or ANY) transceiver. It also includes a combination of features that many might not always take the time to include in their projects. Considerable effort has been made to assure that in this design, the RIT (RX frequency offset control) voltage and the TX frequency offset control signals are immune to supply voltage variations. IC1 requires a regulated +6 V voltage for proper operation......
A cathode follower based on the 6BL7 or 6BX7 is ideal for output. I used a mu-follower circuit with no feedback, a 12SN7 as the gain stage, and a 6BL7 as the cathode follower/current source. (I have many old GEs I wanted to use, and converting to 6SN7 means simply changing the hookup to the 24V filament transformer). You might argue that the current source should be a pentode of highest possible gain, but pentodes can be noisy, and one of my design goals was minimalism......
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