Quartz Crystal Tester circuit diagram

Using this Quartz Crystal Tester circuit presented in this schematic diagram we can test the functionality of the crystal quartz .
The crystal tester schematic diagram is very simple and require few common  components  . The Q1 transistor  2N3563 and its associated components form an oscillator circuit that will oscillate if a good crystal quartz is connected to the test clips . 

The from the oscillator is rectified using two 1N4148 diodes and filtered by the C1 capacitor , then the positive voltage is applied to the Q2 transistor 2N3563 causing it to conduct . When the transistor Q2 conduct the LED1 will glow  indicating that the tested crystal quartz is ok .  The quartz tester circuit must be powered using a 9 volts DC power supply or a 9 volts battery .