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Video Mixer Circuits
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Desheng 1012 12-band television sound radio circuit diagram
Desheng 1012 12-band FM, MW, SW, TV sound radio circuit diagram as follows:
Video enhancement circuit diagram
Enhancement circuit as shown in the high-frequency component of the video signal can be increased, thereby enhancing the contrast of the TV image, it can also be connected to t
EPSON PHOTO 830U printer power circuit
EPSON PHOTO 830U printer power circuit It shows EPSON PHOT0 830U printer power supply circuit, which belongs to the switching power supply. In normal operation, the power suppl
Digital Camera 5 channel power supply MAX1565
Digital Camera 5 channel power supply MAX1565 5 shows a digital camera power supply channel MAX1565, seen from the figure, the chip offers a number of road width signal generat
TV Pattern Generator (ZNA234E)
This Circuit uses the ZNA234E IC which makes available all the waveforms necessary to produce the crosshatch, dot and greyscale test patterns on a television screen. The composite video output can be injected directly into the video input of a receiver or used to drive a modulator for connection to the aerial socket.
The circuit is built around a 4001 quad two-input NOR gate, it provides switch selectable auto-advance times of 5, 10, 15, 20, 25 or 30 seconds through the remote-control socket of your projector. Ula and Ulb form an astable multivibrator, with its operating frequency dependent on the number of timing resistors switched into the circuit via S2....
One leg of the photocell (Rl) is tied to the +15 volt supply and the other end is connected to ground through resistor R2, forming a voltage-divider network. The non-inverting input of the 741 op amp, IC1, is tied to the junction formed by Rl and R2, while its inverting input is grounded through resistor R3. When switch SI is pressed, another...
Sound trigger for flash unit
The circuit is based on operational amplifier IC1 used in the noninverting amplifier mode. Rl and 2 set the gain at about 500. RV1 (sensitivity) biases the noninverting input to the negative supply. Ql provides the relatively high trigger current required by the triac. When a signal is received by the microphone, the signals are amplified (by...
The FM oscillator/modulator is a voltage-control led oscillator, which exhibits a nearly linear output frequency versus input voltage characteristic for a wide deviation. It provides a good FM source with a few inexpensive external parts
The VHF frequency is generated by a tuned Hartley oscillator circuit. Resistors R2, R3, and R4 bias the transistor, with tapped inductor LI and trimmer capacitor Cl forming the tank circuit. Adjusting Cl determines the frequency. Capacitor C2 provides positive feedback from the tank circuit to the emitter at Q1. Capacitor C4 provides an RF...
if the timer is triggered with a continuous pulse train in the monostable mode of operation, the charge time of the capacitor can be varied by changing the control voltage at pin 3
Automatic contrast meter
The circuit arrangement consists of a photo-amplifier which feeds a voltage derived from varying light levels in an enlarger to a pair of peak detectors. One follows the peak positive voltage and the other the peak negative voltage. The capacitors used for storing the voltage peaks in the followers also form part of sample and hold circuits...
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...
Photo stop action
This circuit gives multiple "stop-action" photographic effects like showing a bouncing ball in up to nine locations in a single photograph. The circuit will automatically fire the bulbs sequentially with the time between each firing variable. The circuit is functionally complete except for the actual firing system. In many cases, a simple SCR...
Sound activated strobe trip
Take strobe-flash pictures the instant a pin pricks a balloon, a hammer breaks a lamp bulb or a bullet leaves a gun. Use a transistor amplifier of 1-watt rating or less. (It must have an output transformer) The amplifier is terminated with a resistor on its highest output impedance, preferably 16 ohms
Flash slave driver
In photography r a separate flash, triggered by the light of a master flash light, is often required to provide more light, fill-in shadows etc. The sensitivity of this circuit depends on the proximity of the master flash and the value of Rl
Remote flash trigger
Transistor Ql is a light-activated silicon-controlled rectifier (LASCR). The gate is tripped by light entering a small iens built into the top cap. To operate, provide a 6-in. length of stiff wire for the anode andcathodeconnections and terminate the wires in a polarized power plug that matches the sync terminals on your electronic flashgun...
Two-stage wideband amplifier
A wideband high gain configuration using two SL550s connected in series. The first stage is connected in common emitter configuration, the second stage is a common base circuit. Stable gains of up to 65 dB can be achieved by the proper choice of Rl and R2
Jfet bipolar cascode video amplifier
The JFET-bipolar cascode circuit will provide full video output for the CRT cathode drive. Gain is about 90. The cascode configura-tioneliminates Miller capacitance problems with the 2N4091 JFET, thus allowing direct drive from the video detector
The amplifier picks up the TV"s audio output signal and amplifies it to drive a set of earphones for private listening. It is built around an LM324 quad op amp and an LM386 low-power audio amplifier.
Two IC rf modulators convert a suitable baseband video and audio signal up to a low VHF modulated carrier-Channel2 through 6 in the U.S., and 1 through 3 in japan-the LM1889 and the LM2889. Both !Cs are identical regarding the rf modulation function, including pin outs, and can provide either of two rf carriers with de switch selection of the...
Because the transconductance of an operational transconductance amplifier is directly proportionai to /ABc. the amplification of a signal can be controlled easily. The output current is the product from transconductance X input voltage. The circuit is effective up to approximately 200kHz.
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...
Because power MOSFETs offer high power gain at both audio and radio frequencies, they are useful in many areas of radio-circuit design. For rf applications, a MOSFET"s large safe operating area, V0 s vs ! 0, protects it against damage from reflected rf energy. As a modulator, a MOSFET"s transfer linearity aids fidelity. In the...
Switching diodes are used to fire the neon lamps when negative-peak modulation hits 50. 60, and 100%. To use the circuit, keep an eye on the lamps.
This application uses the timer connected for astable (free-running) operation, with a modulating signal again applied to the control voltage terminal.
In this application, the timer is connected in the monostable mode. The circuit is triggered with a continuous pulse train and the threshold voltage is modulated by the signal applied to the control voltage terminal at pin 5. This has the effect of modulating the pulse width as the control voltage varies.
When the carrier level is adequate to switch the cross-coupled pair of differential amplifiers, the moduÂ· lation signal, which has been applied to the gate, will be switched at the carrier rate, between the collector loads. When switching occurs, it will result in the modulation being multiplied by a symmetrical switching function. If the...
You can set the interval from about 5-30 seconds. A relay operates the slide-change mechanism. Op amp Ul forms a sort of Schmitt trigger. Resistors Rl and R2 bias the noninverting input at pin 3 of Ul to half the supply voltage. Feedback resistor R3 increases or reduces the bias to pin 3, depending on whether the output of Ul is high or low....
Transistor Ql remains off until the magnetic switch connected to Jl closes. When that happens, the 9 Vis connected through Rl to Ql"S base. Ql turns on, thereby charging C2 through relay Kl, which causes Kl "s contacts to close. Since the contacts connect viaJ2 to the remote control jack in the camera, which in tum connects to the camera"s...
The NE555 circuit is a basic one-shot timer with a relay connected between the output and ground. It is triggered with the normally open momentary contact switch, which when operated, grounds the trigger input at pin 2. This causes a high output to energize Kl which closes the normally open contacts in the lamp circuit. They remain closed...
Insulated-gate, field-effect transistor (IGFET), Q2 and silicon photo cell Zl form the heart of this circuit. Transformer T1 is an audio-output type, but it"s reversed in the circuit. A sudden flash from a photoflash unit detected by Zl sends a voltage pulse through the low-impedance winding of Tl via Rl. That voltage pulse is stepped-up in...
Ultrasonic distance finder circuit
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
Digital Signal Integrity
Interconnection and Timing of Digital Circuits
CMOS Circuits Tutorial