YPBPR to RGB Video Converter Circuit Using LT6552

This is a design circuit for LT6552 amplifiers connected to convert component video (YPBPR) to RGB. This is the figure of the circuit;

The LT6552 is a video difference amplifier optimized for low voltage single supply operation. The LT6552 features 75MHz – 3dB bandwidth, 600V/µs slew rate, and ±70mA output current making it ideal for driving cables directly. This circuit maps the sync on Y to all three outputs, so if a separate sync connection is needed by the destination device.

Magnetic Reed Switch Alarm Circuit

This circuit is kind for made to be an alarm, both for home and handbags. If it is installed for home it will placed on door or windows, and if it is installed for bags or handbags it will placed in the bag. This circuit consists of a small magnet and a reed switch. If the magnet looses its contact with the reed switch, SW1 opens, the circuit starts oscillating and the loudspeaker emits a loud alarm sound. So this circuit suitable for use as an anti-theft alarm. This is the figure of the circuit;

This circuit uses A complementary transistor-pair which is wired as a high efficiency oscillator, directly driving a small loudspeaker. Low part-count and 3V battery supply enable a very compact construction. The loudspeaker’s dimensions are limited only by the box that contain it. If the circuit is used as anti-bag-snatching, SW1 can be replaced by a 3.5mm mono Jack socket and the magnet by a 3.5mm. Do not supply this circuit with voltages exceeding 4.5V: it will not work and Q2 could be damaged.

Low Distortion Crystal Oscillator Circuit

This is a design circuit for Low Distortion Crystal Oscillator circuit. This circuit generate a sine wave that has low phase noise and distortion. This circuit can be used to perform a crystal with less than 1mV dissipated in crystal. The crystal is used to filter the signal current. This is the figure of the circuit;

 

If the impedance loads is low, the JFET will drive the impedance. When the loads is about 50ohm, it will better if an emitter follower combined with a voltage step-down transformer or matching network for further buffering. The value of C3 determined the output voltage, if the lower output voltage is required, the C3′s value should be increased and decrease the value of C3 when the larger output voltage is needed. If overtone crystal is used, a choke should replace the 1K emitter resistor. This choke must be resonates with C2 at a frequency slightly above the fundamental frequency for third overtone crystals. When uses the high-Q overtone crystal, the value of C3 should be lower because the High-Q overtone crystals should be driven at much lower levels than  fundamental  crystals. Besides that, the output level should be set as low as possible. If the crystal’s rated  power or current is  known, the drive level can be measured. To measure drive level temporarily connect a 100 ohm across C3 and measure the signal level on the source of the FET. The crystal current is determined by V/100.

LASER Door Alarm Circuit

This is a circuit for laser door alarm is based on the interruption of Laser beam. A low cost Laser pointer is used as the source of light beam. When somebody breaks the laser path, the alarm will be generated for few seconds. This is the figure of the circuit;

 

The laser door alarm circuit has two sections. The laser transmitter is a laser pointer readily available. It should be powered with 3 volt DC supply and fixed on one side of the door frame. The receiver has a Phototransistor at the front end. L14F1 NPN Darlington phototransistor is used as the laser sensor. IC1 is used as a voltage comparator with its inverting input tied to a potential divider R2-R3. So that the inverting input is kept at half supply voltage. As a result, output of comparator remains low. LED and Buzzer remain off in this state. When a person crosses the door, laser beam breaks and T1 cease to conduct. Collector voltage of T1 rises and voltage at pin 3 of comparator increases and its output becomes high. This activates LED and buzzer. Capacitor C1 keeps the base of T2 high for few seconds even after the output of IC1 becomes low again. C2 gives current to the buzzer for few seconds even after T2 turns off.