Friday, August 19, 2011

Simple Special: Y = 1/X

Our customer needed a simple mathematical inverter: Output = (Constant) x (1/Input). Our standard product line includes analog division.

We simply disconnected input A and tied it internally to full scale.

The key requirement was that the user properly specify the input/output relationship. (Note that at 0% input the output would be 1/0 = infinity.) This application required:

Input = 1 volt, Output = 5 volts

Input = 2 volts, Output = 2.5 volts

Input = 5 volts, Output = 1 volt

Mathematically this is: Output = 5 / Input.

We tied input A to a fixed internal voltage and set the instrument's gain appropriately.

JH Technology offers add, subtract, multiply, divide, square and square root functions in plug-in modules, DIN-rail transmitters and field mount transmitter/displays.

Tuesday, November 8, 2011

Product Focus - Pulse Conditioner

MODEL JH2376

PULSE CONDITIONER

Full-featured Model JH2376 is the "big brother" to our low-cost JH376/JH377 pulse amplifier & converter (blog posting Oct 10, 2009). Fully isolated and capable of handling voltages from 20mV to 250Vrms (700V peak-to-peak) it serves applications ranging from tachometers and flow turbines to power and VFD (variable frequency drive) frequency monitoring. The input is safely isolated and converted to a 5V logic pulse output.

Adjustable sensitivity and optional filtering allow the user to tailor the unit for each application, optimizing sensitivity and frequency response versus noise rejection. DIN-rail mounted, the JH2376 is available with 115 and 230Vac power options.

Here's a link to the spec sheet: JH2376 Pulse Conditioner

Our previously-announced pulse conditioners are:

• Model JH376 Pulse Amplifier. Millivolt inputs, dual channel, low cost, nonisolated.
• Model JH377 Pulse Converter. Converts 5V logic to open-collector and vice versa. Dual channel, low cost, nonisolated.

We also make:

• DC to Frequency Converters (Integrators: Models JH7500 & JH7501. JH7500, 5V logic pulse or open-collector output. JH7501, relay contact output, low pulse rates only. Plug-in style.
• Model JH7010I Frequency to DC Converter (Frequency Input Transmitter). Plug-in style, fixed range.
• Model JH7580 Frequency to DC Converter (Frequency Input Transmitter). Plug-in style, user-rangeable.
• Model JH5700 Frequency to DC Converter (Frequency Input Transmitter). DIN-rail mount, fixed range.
• Model JH1700 & JH1720 Frequency Input Alarm Trips. Plug-in style, fixed range. JH1700, single trip. JH1720, dual trip.

A well-known company needed to duplicate a thermocouple alarm they had bought from Action Instruments decades ago. Action was no longer able to provide it so they turned to us.
Action's original "Action Pak" line (Action's trademark) once included alarm modules with extra options such as retransmitting outputs and remote setpoint inputs. 20-pin headers (pin bases) were required to provide the extra connections. As far as we are aware these headers are no longer available.
Our customer's requirement was a nonstandard version of one of those alarms. We replied that we could provide the same function but with a different connection arrangement. This was not acceptable - it was for a nuclear power application and they could not vary the system design. Only one piece, but they were willing to pay for it.

Once again we got lucky. In 1995 we had purchased some 20 pin headers for another customer's need and had a handful left. Our customer bought one (couldn't convince them to buy a spare) - even sent an inspector to Florida to do a source inspection. That was 2008. In 2009 they again bought one and just now ordered two more! Possible future problem - after this order we have only five headers left.
(Note: We do not sell nuclear-approved products. This alarm was sold as "standard commercial quality" for a noncritical application.)
Technical detail: the custom alarm module has two retransmitting 0-1V analog outputs, one proportional to temperature and the other proportional to the setpoint. Our customer was able to supply us with Action's specifications and we designed it to be functionally identical. Here's the functional diagram.

Last year we spotlighted a new design we'd done for a customer needing a quantity of fast-response transmitters. We've now turned it into a standard product offering.

Available on most of our DIN-rail transmitters (JH5000 Series), Option HS output is approximately complete (95% response) in 0.001 seconds. It is not available on AC input or frequency input transmitters, as these require filtering to function properly.  Frequency response is 3dB down (0.707 times the DC gain) at approximately 600 Hz.

• Add
• Subtract
• Multiply
• Divide
• Square Root
• Square Function

• Sum with unequal input weightings (for example, add flows from two different-size flowmeters or power from two different transducers).
• Unequal input & output ranges (for example, input = 0-10Vdc, output = 4-20mAdc)
• Output = A x B / C
• Alarms with math functions
• Others - let us know what you need

Alcoa added temperature and pressure sensors to the gas lines, and JH Technology was able to create a mass flow Minisystem using signal conditioners. Five modules convert the turbine pulses to DC, perform multiplication and division, produce both 4-20mAdc and pulse rate outputs proportional to mass flow in SCFH (Standard Cubic Feet per Hour) and provide 24Vdc power to the pressure and temperature sensors. The modules were premounted and wired on a panel and placed inside a NEMA-4 field enclosure.
Alcoa reported that the system provided significant savings compared to the costs of new flowmeters, and even more by eliminating the need for piping changes.

Pulse Amplifier:Special Product - leads to a second special - then two standard products - and then yet a third special!

A bit of "fun" history here - our standard Models JH376 & JH377 were introduced  last year (blog entry October 10, 2009).
In 2001 an engineer at a Canadian company - lets call it "Company A" - contacted us. They were using another manufacturer's pulse amplifier which worked but was inconvenient to mount in their system. We quoted, designed and sold them a functional equivalent in a DIN-rail mount case. The engineer later left and the orders stopped.
The same engineer called us in 2004, now with a different firm ("Company B") and with a modified set of requirements. He needed different - and adjustable - sensitivity, different filtering and the ability to accommodate both mag pickup and logic pulse inputs. We worked with him to prototype and develop a new design. They ordered regularly for about two years but then, early 2007, the orders stopped. (We later learned he'd gone back to "Company A".)
So - we now had a design but no customers. We decided to "run it up the flagpole" as a standard product and see what happened. After reviewing both companies' requirements plus competitive products we revised the standard product's filtering and sensitivity specs a bit. Introduced a year ago, it's been a modest success including a new OEM customer.
And now. "the rest of the story". In August "Company B" called again. They reordered their version but really wanted yet a different set of requirements. We again worked with them to develop a new version which they have since bought. We also contacted the original engineer at "Company A" but their systems have changed and they no longer need pulse amplifiers.

As most of you know, many years ago Action Instruments introduced plug-in "Action-Pak" transmitters and alarms.(Note: Action-Pak is an Action Instruments trademark.) Action grew, became a highly regarded company, added other product lines and were eventually acquired by Eurotherm. Their line still includes Action-Paks but some models are no longer available.
One of our favorite stories - a company called us desperately looking for a special version of an old Action module. They told us, not only could Action no longer make it, they insisted they never had! The customer forwarded us a copy of Action's user's manual.
OK - a special - a one-piece order - we had to charge for some engineering, but we did it. They've ordered a few more since.
Over ten years ago another company came to us because Action no longer made some of the (standard) products they used regularly. Our product line included them (still does) and that company has become one of our better customers.
We're not trying to knock Action. They are a well-respected, quality company. But if you need plug-in modules they no longer offer, e-mail or call us. We probably can help. (And, our customers rave about our service.)

Unusual Thermocouple Application

Our customer's client had a large spa facility. The controls had been located near the spa, but the client felt they should be moved to a more benign environment, several hundred feet away. The system included four thermocouples. Sending thermocouple signals this distance is expensive, since thermocouple wire (not copper) must be used. Even more basic, sending weak millivolt signals hundreds of feet leaves them subject to interference and signal degradation.
To boost the signals, four standard thermocouple transmitters (our Model JH4130) were added near the spa. Their 4-20mA current signals easily traveled the distance with no degradation. The system designers opted not to change the control system, so it was necessary to convert the current signals back to their original thermocouple voltages. "Reverse" thermocouple transmitters, 4-20mA input, thermocouple output, were needed.
We provided them. We modified our Model JH4300 DC input, DC output transmitters to have the proper millivolt outputs. The most interesting challenge was, the millivolt outputs needed to be connected to thermocouple wires (not copper) for proper connection to the system's thermocouple inputs. This called for the reverse of cold junction compensation (we called it "cold junction un-compensation"). A temperature sensor embedded in the output terminals and some properly-designed circuitry solved the problem

The problem – the laser’s output represents instantaneous position, varying continuously as the filter shakes back and forth. The company needed to convert peak-to-peak displacement to 4-20mAdc input current for the motor drive controllers.
The solution – our Model JH5600 AC Input Transmitter. Because the filters are large and driven by rotating equipment their motion is purely sinusoidal so the relationships between average, RMS and peak values are well known. In this application an input range of 0 to 3.536 volts RMS (odd ranges are not special for us) corresponds to 0 to 10 volts peak-to-peak. We have in the past created special modifications for true peak-to-peak measurement, but this was not required for this application
For those who prefer plug-in style modules, the same function is available in our Model JH6010I.