@▷ Electronic Selector Driven by Relays | Diagram for Schematic

Electronic Selector Driven by Relays

Circuit Project Description

The circuit was aimed to produce an electronic selector for ten alternative sources with the means of showing the result in a 7-segment display being driven by relays.

Terminology 4511 – a BCD to 7-segment decoder driver used to convert the logic states at the outputs of a binary coded decimal (BCD) into signals that will drive a 7-segment display4028 – a BCD to decimal/octal decoder with four inputs that provide a decimal decoded output while a 3-bit binary input provides a decoded octal output used for memory selection control, readout decoding, code conversion, demultiplexing, and address decoding with features such as low outputs on all illegal input combinations, positive logic design, 3V to 18V supply voltage range, and capability of driving one low-power Schottky TTL load over the rated temperature rangeBD679 – a monolithic NPN Silicon epibase power Darlington transistor with resistors and diode in a TO 126 plastic package and is typically used for AF applications due to its high current gain Circuit Explanation

The circuit comprises of a rotating switch step selector S1 that serves as the means for mechanical selection from 1 to 10. Also included in the circuit is an electronic drive consisting of 10 relays RL1 to RL10. The relays may have a voltage of 6 V or 12 V. The use of 7-segment display DSP1 is for the visual indication of the selection. The display is made up of common cathode LED, where the cathode is connected to the common point (ground) on the circuit and usually though a resistor that is often bypassed with a capacitor, placing it at AC ground potential.

The operation of the circuit is based on the connection of the mechanical selections into 4 bit binary-coded decimal (BCD) code. BCD is an encoding for decimal numbers in which each digit is represented by its own binary sequence with the values or digits using 0-9. The BCD code is being managed by the proper polarization of the diodes D1 to D10. During this time is the simultaneous gathering of decimal output by IC2 which is a BCD to decimal decoder.

IC1 is a BCD to 7-segment latch, decoder, or driver which drives the monitor. The circuit can be used for several types of combinations and selections. One way is by adding more LEDs in parallel with the relays RL1 to RL10.

Part List
R1....4= 10Kohms
R5....11= 820 ohms
R12....21= 15Kohms
C1= 100nF 63V MKT
C2= 47uF 25V
D1.....20= 1N4148
IC1= 4511
IC2= 4028
Q1-10= BD679
DSP1= Display 7 Segment Common Cathode
S1= 1X10 Step Selector
RL1....10=  6V or 12V Relay
Application

The theory used for the circuit of electronic selector is being used in packet-switched wavelength division multi-access (WDMA) networks and other analog adjustment applications. There are some circuits that utilize an electronic selector switch for telemetrical use with an impedance measuring circuit like those used in radiosondes.

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