Contactless Mains Voltage Indicator
This is a CMOS IC (CD4033) based circuit which can be used to detect presence of mains AC voltage without any electrical contact with the conductor carrying AC current/voltage. Thus it can be used to detect mains AC voltage without removing the insulation from the conductor. Just take it in the vicinity of the conductor and it would detect presence of AC voltage. If AC voltage is not present, the display would randomly show any digit (0 through 9) permanently. If mains supply is available in the conductor, the electric field would be induced into the sensing probe. Since IC used is CMOS type, its input impedance is extremely high and thus the induced voltage is sufficient to clock the counter IC. Thus display count advances rapidly from 0 to 9 and then repeats itself. This is the indication for presence of mains supply. Display stops advancing when the unit is taken away from the mains carrying conductor. For compactness, a 9-volt PP3 battery may be used for supply to the gadget
DESCRIPTION OF SEVEN SEGMENT DISPLAY :-
7-Segment Numeric LED Displays
In industrial PLC applications, one of the old, but simpler methods of displaying numeric information is to use one or more 7-Segment numeric displays connected to an output card of a PLC... Although it is possible to build such a display yourself, it is far more common to employ a pre-manufactured product such as the 4-digit panel mount unit shown at the top of this page...To correctly interface a PLC to such a display, it helps to first understand what basic electronic components are typically employed in their makeup, and how this effects our task of interfacing to, and programming such a unit... Although both LED and LCD numeric displays are readily available, and interfaced similarly, we'll concentrate on the more common LED units in the examples to follow...
Features of CD4033BMS :-
• High Voltage Types (20V Rating)
• Decoded 7 Segment Display Outputs and Ripple
Blanking
• Counter and 7 Segment Decoding in One Package
• Easily Interfaced with 7 Segment Display Types
• Fully Static Counter Operation DC to 6MHz (typ.) at VDD =
10V
• Ideal for Low-Power Displays
• “Ripple Blanking” and Lamp Test
• 100% Tested for Quiescent Current at 20V
• Standardized Symmetrical Output Characteristics
• 5V, 10V and 15V Parametric Ratings
• Schmitt-Triggered Clock Inputs
• Meets All Requirements of JEDEC Tentative Standards
No. 13B, “Standard Specifications for Description
of “B” Series CMOS Device’s
Applications of CD4033BMS :-
• Decade Counting 7 Segment Decimal Display
• Frequency Division 7 Segment Decimal Displays
• Clocks, Watches, Timers (e.g. ÷ 60, ÷ 60, ÷12 Counter/
Display
• Counter/Display Driver For Meter Applications
Description of CD4033BMS :-
CD4033BMS consists of a 5 stage Johnson decade counter
and an output decoder which converts the Johnson code to a 7
segment decoded output for driving one stage in a numerical
display.
This device is particularly advantageous in display applications
where low power dissipation and/or low package count is
important.
A high RESET signal clears the decade counter to its zero
count. The counter is advanced one count at the positive clock
signal transition if the CLOCK INHIBIT signal is low. Counter
advancement via the clock line is inhibited when the CLOCK
INHIBIT signal is high. The CLOCK INHIBIT signal can be used
as a negative-edge clock if the clock line is held high. Antilock
gating is provided on the JOHNSON counter, thus assuring
proper counting sequence. The CARRY-OUT (Cout) signal
completes one cycle every ten CLOCK INPUT cycles and is
used to clock the succeeding decade directly in a multi-decade
counting chain.
The seven decoded outputs (a, b, c, d, e, f, g) illuminate the
proper segments in a seven segment display device used for
representing the decimal numbers 0 to 9. The 7 segment outputs
go high on selection.
http://www.datasheetcatalog.org/datasheets/134/108993_DS.pdf
