#2 SIMPLE ELECTRONIC LETTER INDICATOR USING LABVIEW

Here, in this small project, whenever an interrupt is placed between the photo-transistor (L14F1) and green LED, a message will be displayed that the letter has been dropped and the indicator light will be turned on. The block diagram (LABVIEW block diagram), the circuit (on bread board) and the simulation results are as shown below.  

• The above circuit is implemented on the bread board and the output voltage across the photo transistor is given to the 'aI0' channel on NI myDAQ.
• After this, a block diagram is implemented in NI Labview using DAQ assistant as an interface between hardware and software as shown below.

• From the block diagram, we see that if the voltage across the PT L14F1 exceeds 10V, indication light will be turned ON and a message will be displayed - "THE LETTER HAS BEEN DROPPED".
• Here is the practical circuit interfaced with myDAQ

Outputs are as shown below. When the letter isn't placed, indication light will be in OFF state. When any interrupt like letter is placed, indication light will be ON and message will be displayed.

When letter isn't placed

Interrupt is placed between LED and L14F1

Message is displayed as shown and indication light is turned ON

When these PT and LED are mounted on the inner walls of letterbox, and the info is passed in a wireless fashion, user will be able to understand that there is a letter for him even when he is in his house and is infront of PC.

Thank you, for any further information, contact me at +Prajwal Kotamraju