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Various simple electronics projects for beginners

Various simple electronics projects circuits diagrams for hobbyist and beginners . Simple circuits, mini projects with diagrams and description from many electronics categories.

Simple electronic horn circuit diagram

This electronic horn circuit is a very simple and easy to construct horn circuit that can be used for bikes or some other vehicles or applications .

This electronic horn circuit use only one gate of a 4093 quad 2 input NAND Schmitt trigger , connected in a low frequency , square –wave oscillator circuit .As you can see in the circuit diagram the output of the oscillator ( pin 3) drives the gate of Q1 transistor and the drain of the IRF511 FET drives a small horn speaker .  The output frequency of the horn’s output can be modified by adjusting the R1 potentiometer .
For this simple horn circuit you need to use a 12 volts regulated power supply circuit .

Simple horn electronic circuit diagram

ULN2429A liquid detector circuit diagram

This electronic liquid detector circuit diagram is based on the ULN2429A monolithic bipolar integrated circuit designed for  detecting the absence or presence of many different types of liquids  . The ULN2429 electronic liquid detector circuit can be used in automotive , home or industrial applications  .
The absence or presence of the liquid is determined by comparing the loaded probe resistance (probe immersed in the fluid ) with an internal or external resistance .  At the output you can connect a LED , incandescence lamp , loud speaker or even  such relays or solenoids, but  just I you connect at pin 12 a capacitor , to provide a dc output  ( typically the output signal is a square wave ) .

If you need to connect at the output a device that need more than 30 volts you can use the ULN2429A-1 which is identical , but support devices with operation up to 50 volts .

Main features of the ULN2429A are :  high output current , AC or DC output , single wire probe , low external parts  require , reverse voltage protection , internal voltage regulation .
This fluid detector electronic circuit need to be powered using a power supply that provide an output voltage between 10 and 16 volts .

ULN2429A fluid detector circuit diagram uln2429 electronic fluid detector circuit schematic

UM3561 siren alarm circuit diagram

This siren alarm circuit diagram is based on a specialized IC UM3561 , which is a low power CMOS LSI specially designed for this type of applications . The UM3561 siren alarm contains all needed parts ( oscillator , selector  circuits , programmed mask ROM ) to simulate siren sound using few external components .
The siren circuit require a power supply circuit around 3 volts and has a low current . The UM3561 siren sound generator circuit has possibility to generate four types of sounds : police siren , fire engine siren , ambulance siren and machine gun sound .
The transistor used in this project must be 2SC9013 , 2SC8050 or similar type  .
The speaker used at the output must have 8 ohms impedance and a 0.2 watts power .
As you can see in these three circuit diagrams , the configuration for the siren is very simple .
Police siren , fire engine siren , ambulance siren and machine gun sound .

UM3561 electronic police fire engine ambulance siren machine gun siren circuit diagram

Police siren , fire engine siren , ambulance siren .
UM3561 electronic police ambulance fire engine siren circuit diagram
Police siren and machine gun sound .
UM3561 electronic police siren machine gun circuit diagram

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