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Electronic and electrical testers circuit diagrams electronics projects

Testers electronic circuit diagrams electronics projects for electronic components and circuits.

LM3914 battery tester circuit diagram

This battery tester circuit is designed using the LM3914 integrated circuit and some electronic components. Battery voltage is compared with a reference voltage obtained from an internal source. Reference voltage (pin 8) can be set between 1.5 V and 2.7 V, R1-R2-P1. Potential voltage pin 8 be the head scale LED string. This means that if the voltage is 1.5 V, each LED will symbolize a voltage of 150 mV. We recommend setting the reference voltage from 1.5V NiCd battery, 2.0 V for dry battery. The resistor R1 sets a current of 12.5 mA for each LED.

Circuit Diagram: 
LM3914 battery tester circuit diagram

Simple logic tester circuit

Using this circuit diagram can be designed a very simple logic tester consists of two comparators, the system works with different reference voltages supplied by different voltage dividers. R3-R4-R5 divider provides a voltage of about 40% from Ucc voltage, pin 6 of IC1b, and an approximately 16% of Ucc, pin 3 of IC1a. When Ucc = 5 V, the voltage is exactly the threshold comparators TTL (0.8 V and 2.0 V).
Similarly, R6-R7-R8 divider voltage supply 23% and 73% of UCC's IC1a pin 3 respectively IC1b's pin 6 (the standard threshold levels correspond CMOS comparators).

Circuit Diagram: 
Simple logic tester circuit diagram

Electronic tester for quartz crystals

Using this circuit diagram can be designed a very simple electronic tester for quartz crystals. At this tester for quartz crystals a LED indicates if crystal tested oscillate or not .Tester was designed primarily to be used to test crystals with fundamental frequency between 1 MHz and 30 MHz.
Many crystals in the range 1-5-4 MHz oscillate easier when switch S1 is closed.

The typical current through the tester does not exceed 30 mA at a supply voltage of 9 V

Circuit Diagram: 
Electronic tester for quartz crystals circuit diagram


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