Showing posts with label Timers-Counters. Show all posts
Showing posts with label Timers-Counters. Show all posts

Monday, September 08, 2008

Electronic Shift Monitor

The Security Guard duty monitor below, shown in eight circuits at Digital Circuits - 1 are examples of logic circuits, i have converted them from the DOS Orcad to Orcad 9 and corrected some errors a few years back.

Electronic Shift Monitor - delabs

These circuits can be used for looking at the logic blocks or to learn. This product was built and sold to some firms many years back. Now these designs are best done with a PIC or Atmel chip. Here is the user manual

This circuit was done with CMOS CD40xx type of ICs. A RAM was used to store the Day/Time LED Status.

It was to monitor the Alertness of the Security Guard. Periodically the Unit will Buzz and Flash and the Security Guard has to press a Big Button to indicate he is awake, alert, agile and around the Unit.

All Green means fine, few Red LEDs means the Guard was sleeping or gone away from some times. All Red means Security Guard is missing. :-)

Saturday, April 05, 2008

Tacho Counter for Speed and Quantity Measurement

This was a Custom Built Product for Converting a 10-100 V Signal from a Motor Tacho to pulses, to indicate the distance moved by Conveyor belt with Job Material. The Digital Indicator would indicate the speed and the Mechanical Counter would Log Quantity of Materials Moved.

Process Control Instrumentation

Tacho Counter

The voltage was first brought down to low levels with an attenuator and zener protection. A VCO and a monostable created a train of pulses. These pulses drive a darlington transistor pair which operates the Electromechanical Counter that has a Solenoid. The voltage is also scaled, calibrated and displayed on a Digital Voltmeter.

The circuits are partially shown here, two versions.

Voltage to Frequency Converter ICL8038

In this the VCO chip is 8038, it is hard to procure, but it is an excellent chip.

VCO - Voltage Controlled Oscillator using Opamps

This is using opamps, hard to configure and build, but a proven design.

The VCO can also be built by a Microcontroller chip which has an analog input. Any I/O port can be the Oscillator output. This is easily possible as this system is within the 1 MHz range.

Analog Blind Dial On Delay Timer

It is called analog dial timer as it has no digital display, but the chip is digital it is CD4541. It is Mains operated, you could make on-delay or off-delay. By changing the caps and resistors or with even dip-switches you could get timing of few seconds to many hours. Circuit is Analog Timer 4541 .

Analog Blind Dial On Delay Timer

Some timers energize the relay after a set delay on power start. Some start with relay energized and turn off after set time. Motors and big systems cannot take fast turn-on and turn-off, Some systems will require sections or modules to start one after another as they are interdependent. So Timers in automation were made to effect such delays, the early ones were mechanical clockwork.

Analog Timer

The CD4541BC Programmable Timer is designed with a 16-stage binary counter, an integrated oscillator for use with an external capacitor and two resistors, output control logic, and a special power-on reset circuit. The special features of the power-on reset circuit are first, no additional static power consumption and second, the part functions across the full voltage range (3V¨C15V) whether power-on reset is enabled or disabled.
  • Available division ratios 28, 210, 213, or 216.
  • Increments on positive edge clock transitions.
  • Built-in low power RC oscillator.
  • Oscillator frequency range . DC to 100 kHz.
  • Power on Auto reset initializes all counters.

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IA Instrumentation 02
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Analog Mux - Data Acquisition


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