Posted on Oct 27, 2012

This indicator senses the switching on and off of the 48-V de line voltage and transmits the pulses to logic circuitry. An Hl1A10 threshold coupler, with capacitorfiltering, gives a simple circuit which can provide dial pulse indication, and yet reject high levels of induced 60-Hz noise. The DHD805 provides reverse bias protection for the LED during transient over-voltage situations.

Click here to download the full size of the above Circuit.

The capacitive filtering removes less than 10 ms of the leading edge of a 40-V dial pulse, while providing rejection of up to 25-V rms at 60Hz.

Leave Comment

characters left:

New Circuits



Popular Circuits

RS232 cable modem
Design and making of the stabilized voltage supply of switch
Crystal audio oscillator circuit
buffer amplifiers
Infra-red Level Detectors
Stormwise VLF Radio Electronic Project
Fans can light three-gear speed control circuit