Showing posts with label sensitive. Show all posts
Showing posts with label sensitive. Show all posts
Tuesday, September 9, 2014
Super Sensitive Intruder Alarm
Here is the schema diagram of an ultra sensitive intruder alarm.The shadow of an intruder passing few meters nearby the schema is enough to trigger the alarm.
Here IC2 uA 741 is wired as a sensitive comparator ,whose set point is set by R6 &R7.The voltage divide by LDR and R9 is given at non inverting pin of IC2.At standby mode these two voltages are set equal by adjusting R9.Now the out put (pin6) of comparator will be high.Transistor Q1 will be off.The voltage at trigger pin of IC1 will be positive and there will be no alarm.When there is an intruder near the LDR the shadow causes its resistance to increase.Now the voltages at the inputs of comparator will be different and the out put of IC2 will be low.This makes Q1 on.This makes a negative going pulse to trigger the IC1 which is wired as a monostable multivibrator.The out put of IC1 will be amplified by Q2 (SL 100) to produce alarm.
Notes
* To setup the alarm ,power up the schema and adjust R9 so that LED D1 goes off.
* The LDR can be housed in a dark tube to increase sensitivity.
* The sensitivity is very important here.If you cannot adjust the required sensitivity properly, use one LOW resistance (~1K ) POT in series with R9 for fine adjustment.
Friday, September 5, 2014
Water sensitive circuit diagram
This is a water sensitive schema diagram.I suppose this schema will give you lots of benefits .I have modified this schema up to some extent and have added to our water pump moter (230 v) I think you also can use this schema for various purposes.Here I have used common IC Bc109. When you fix the sensor Dont forget to fix it over the water level.This schema operates with 4.5V to 6v.If you want to operate your water pump 230V 0r 110V you can use a rellay for that.Then this schema will switch on or off that rellay( use 6V rellay)
Note
# Use a PCB to build this schema
# Dont supply more than 6V
#Dont forget to fix the sensor over the water level
Subscribe to:
Posts (Atom)
