Wiring Schematic Diagram Guide

Simple Crystal Tester Circuit Diagram. Most electronics project working with high frequency utilizes crystal in order to generate frequency as oscillator. It is used instead of coil. Coil can be checked with multi-meter if there is any fault, but checking of crystal completely is difficult. In order to solve this problem a simple project using few components is designed call crystal tester.

This circuit consist two NPN transistors, two diode with few passive component. The crystal under test is combining with transistor T1 which further work as oscillator. The combination of transistor T1, crystal under test and capacitors C1 and C2 is work as colpiitt oscillator. If the testing crystal is good then it works as oscillator with transistor T1. The output of oscillator is rectified and filtered by diode D1 and capacitor C2 respectively and given to base of transistor T2. The signal given to base conduct transistor which further glow the LED connected to the collector through resistor R3. If the testing crystal is faulty then LED1 does not glow.

PARTS LIST
Resistors (all ¼-watt, ± 5% Carbon unless stated otherwise)
R1 = 27 KΩ
R2 = 1 KΩ
R3 = 560 Ω
Capacitors
C1 = 0.001 µF
C2 = 100 pF
C3 = 0.001 µF
C4 = 0.004 µF
Semiconductors
D1, D2 = 1N4148
T1, T2 = BC550C
LED1 = Green
Miscellaneous
SW1 = push to on switch

How to build a Crystal-controlled-reflection-oscillator circuit diagram . This is a simple crystal controlled reflection oscillator circuit, this unit is easily tunable and stable, consumes little power, and costs less than other types of oscillators tlmt operate at the same frequencies. This unusual combination of features is made possible by a design concept that includes operation of the transistor well beyond the 3 dB frequency of its current-versus- frequency curve. 

The concept takes advantage of newly available crystals that resonate at frequencies up to about 1 GHz.The emitter of transistor Q is connected with variable capacitor Cl and series-resonant crystal X. The emitter is also connected to ground through bias resistor Rl. The base is connected to the parallel combination of inductor L and capacitor C3 through DE-blocking capacitor and C4 and is forward biased with respect to the emitter by resistors R3 and R4. 

Impedance Z could be the 220-0 resistor shown or any small impedance that enables the extraction of the output signal through coupling capacitor C2. If Z is a tuned circuit, it is tuned to the frequency of the crystal. 

 

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