In the previous project we have discussed a simple touch alarm circuit in which we have used a peizo buzzer as an alarm that was giving a continuous buzzer sound. But in this circuit we have used a UM66 melody IC and a BC548 NPN transistor to amplify the output of the melody IC to drive an eight ohms speaker.
When the pin 2 of the 555 timer IC receives a touch then the output of this IC will go high at pin 3 for a set time period (which depends on the capacitor Cx) and power ON the UM66 IC.
The ON time period can be increased by increasing the value of the capacitor Cx, use 100uF for around 2 minutes and 220uF for 5 minutes ON time. You can also try higher values for further increasing the ON time.











Privacy Policy
Copyright 2013 CircuitDiagram.Org. All rights reserved.
Here is a project of a 555 touch alarm circuit with UM66 melody IC. The circuit will produce a melodious alarm sound for a set time period when someone touches the metal plate / touch plate shown in the schematic and after the set time period is over the circuit will goes off automatically.




 
Sponsored Links
Touch Alarm Circuit With UM66 IC