This electronic project prevents incorrect connection of polarized sources in circuit and is designed using common electronic components. Safety of polarity from the diagram below was dimensioned for a voltage of 12 volts. When connecting correctly voltage to terminals 1 and 2 through RE1 resting contact, diode D1 and the coil current flows once the switch closes the circuit (relay closing, established by contact or connection with device connected).
Using electronic scheme below can be designed a zener diode tester using few electronic parts.
Using this zener tester and a multimeter can be measured and determined with a high precision threshold voltage of a zener diode.Zener voltage can be read with a DC voltmeter connected in parallel with zener diode.
This ULN2004 electronic project circuit diagram design is a very simple water level indicator circuit project . This ULN2004 water level indicator circuit is very simple and require few external electronic parts .
ULN2004 is a high voltage, high current darlington arrays that contain seven open collector darlington pairs with common emitters . Each channel rated at 500mA and can withstand peak currents of 600mA.