Showing posts with label delabs-Portfolio. Show all posts
Showing posts with label delabs-Portfolio. Show all posts

Tuesday, February 02, 2016

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.

Monday, February 01, 2016

Megger or Insulation Tester

Decades ago, when a customer found that my Tera Ohm Meter expensive, He suggested the specs for this low cost scaled-down model. This was found useful for people sub-contracting Telecom Equipment Manufacturing.

Insulation Tester

Test and Measurement Instruments

This probably went upto 500V and 100V with a Toggle Switch and measured upto 1 Giga Ohm or 1000 Mega Ohms. The test voltage would be applied on the Switch, Connector or Magnetics to measure the leakage current in its insulation. The leakage current would be converted to voltage, clamped with diodes and fed to the Vref of a 7107 which displayed the Insulation Resistance by doing a 1/x. Normally we use Vin to measure the voltage, in this instrument the Vin holds the Reference.

Monday, January 04, 2016

PLC based PID Controller

Below is a Electrical Control Panel, It has a Strip Chart Recorder which is electro-mechanical, It has a PLC Inside. A handheld PLC Programming unit. The computer is showing the Ladder Logic Program. PLC is based on a embedded uC. The DIN Controllers are Analog + Digital circuits. So you see it is a Electrical Control Panel with Electronics and the PLC Ladder Logic means, Software too.

Process Control Application Notes

This is a PID Controller based Control Panel using a PLC from GE Fanuc Automation. The Computer is a 386 40MHz with 40MB HDD.

PID Controller PLC

Electrical Control Panel Wiring

Multizone Process Scanner

This could take current or voltage inputs from many remote transmitters, 4-20mA or 0-1 V Inputs. Then it would display the calibrated value in a LED display. The Zone number was a digital display. This serves as a monitor of process values. It had a analog output with a digital channel byte-word output for interface with other instruments.

This uses the CD4051-52 for the analog switching. Operating this at +/- 7.5V gives best isolation from channels and low ON resistance. Now you have many types of devices to do this.

Multizone Scanner

When a large area or object has to be heated, many heaters are used. This device can monitor and display the temperature at various points. The Operator then can make adjustments in heating or cooling so that he can maintain Uniform temperature or a Temperature Gradient as specified by the Process.

There are many ways, these scanners are used. Many different parameters like pressure, temperature, level are measured with different sensors and converted to a 4-20 mA level using transmitters for each sensor. Then many parameters can be measured in one equipment, when it needs only periodic attention. As the scan rate can be set from 1 to 50 seconds, the operator will be able to keep a tab on the values or record it. This reduces the real estate required on the control panel. Then the control room can be small, as it has to be at a vantage point, with a birds view of the entire factory floor.

Industrial Process Control Circuits

Wednesday, May 14, 2014

Three Point Preset Counter

This is a prototype of a Preset Counter. It is built with ICM7217. The cabinet is ABS Plastic DIN 96-96. The Panel is Engraved on Acrylic. I don't remember for which application it was used. It has three thumbwheel settings, when the proximity switch counts upto the set-value, the corresponding relay turns ON, with a State Indicating LED on front panel.

Three Point Preset Counter

These can be configured sequentially or to work synchronously, this depends on what customer wants. Both modes may give the same result. In sequential operation, Some of these counters-timers may need to wait for an external trigger or feedback from a limit switch or another process like pressure alarm. Then more Input options may have to be provided.

Counters, timers, analog-process and its interconnectivity makes up the various process loops or chain-reactions in Machine control. The various types of sensors for measurement and feedback of analog and event parameters, monitor the mechanical system and communicate the data to the process instruments. The Actuators like Drives, Solenoids, Pumps, Valves and Heaters act in accordance to the commands of the control system. This regulates and manages the process or machine to deliver consistent and repeatable yield of the end product.

Read More here - Digital Timers, Counters and Clocks

Saturday, March 08, 2014

Sequential Timer - Pressure Switch

This was built in a 96 X 96 Cabinet. It takes the process thru three timer delays and the pressure is measured after a certain stage and at a setpoint the process, job or DUT passes or Fails. It could be stress, strain or load testing on object.

Sequential Timer

User Manual - Sequential Timer - Pressure Switch
Related Resources

Thursday, February 23, 2012

Custom Built Test Instruments

I designed and built many custom "engineered" Test Instruments. They were not prefect, as only one or two were fabricated. That means it will be costly to produce such instruments. It is just like tooling, you have to make some numbers to recover costs, or price it very high to compensate for the wastages and iterations. But things are better off now for building custom instruments. Yet a design firm has to make modules and keep ready, then put together a solution/system, program and ship.

Custom Built Test Instruments

When making custom equipment, you have to have an extended service agreement like 5 years. Also request a minimum order of at least 5. Make your R&D and Inventory Modular. That way it is profitable and some money available for reinvestment on instruments and Equipment for calibration and quality.

Transistor Beta and Vce Tester

This was a Beta Hfe and Vce Measuring Instrument used in Incoming Inspection of Power Transistors made by me 20 years back.

Transistor Beta and Vce Tester

It is a Test and Measurement Instrument to Evaluate the Beta of a Semiconductor Transistor at different Ic and Vce. This was an early custom test instrument.