Saturday, December 26, 2009

Product Spotlight



Field-Mount

Transmitters

with Displays

Designed for outdoor and other wet/dirty environments, our FDT5000 series transmitters feature:

  • Splashproof/ Corrosion Resistant Enclosure per NEMA 4X
  • User-Rangeable 3-1/2 Digit Display
  • Wide Selection of Input Styles
  • Voltage or Current Output Ranges
  • AC and DC Power Options
For full information visit the Field Mount Process Transmitters section of our web site (www.jhtechnology.com/field_mount.htm).
If you don't need a display, we also offer NEMA 4X and explosion-proof enclosures for our plug-in transmitter and alarm modules.

Our home page: http://www.jhtechnology.com/

Sunday, November 29, 2009

Signal Isolator Serves as Subtractor

Measurement and control applications sometimes need a difference (A - B) calculation. Examples include:
  • Liquid level measurement in a closed vessel. Level is proportional to the bottom liquid pressure minus the top ambient (gas or air) pressure.
  • Liquid blending control. Must maintain a zero difference between two measured flow rates.
  • Relative speed control. Control for zero difference between two speed measurements.
JH Technology offers a complete range of multiple input add/subtract instruments, but when the inputs are voltages a lower-cost isolator may do the job.
The figure shows two voltages, both grounded. The signals may come from two pressure or flow transmitters, tachometers or other sources. The isolator's input is connected between the two positive voltages; thus, the input is (V1 - V2). Its output may be set to equal the differential input or it may be scaled up or down, offset or converted to a current signal such as 4-20mA.
We offer plug-in, DIN rail and field mount style isolators and transmitters.

Links: Add/Subtract Transmitter Modules
DIN-Rail style add/subtract transmitters
All Process Transmitters and Alarms

Saturday, November 21, 2009

Simple Specials



CUSTOM
MODIFICATION:
TWO INPUT RANGES

Our OEM customer, who manufactures level control systems, wanted to be able to interface more than one type of level sensor with his system. Specifically, he needed to translate both 4/20mA and 0/5 volt level signals to match his system's input.

Our solution - a modified version of our JH4300 DC Input Transmitter capable of accepting both ranges. For 4/20mA the input is connected to pins 5 & 6. For 0/5 volts pins 4 & 6 are used, plus a jumper between two terminals. This avoids the need to stock two different types of signal conditioners.

More detail. Their level system normally uses a variable resistance level sensor. (In fact, they are a regular customer for our resistance input transmitters.) 4/20mA or 0/5V is only occasionally required, so they did not wish to redesign the system's electronics. Their original request was, could we translate 4/20mA or 0/5 volts to a 0/90 ohm resistance? The answer was no, this would not be a simple modification.

Instead, they determined and we verified that their electronics passes a constant 2.5 mAdc current through the sensor. Thus, 0/90 ohms translates to 0/0.225 volts. We set up our output for this range.

Conclusion: they now are able to work with several types of level sensors without modifying their system. All they need to do is connect the level sensor to our module and connect the JH4300's output to their system's input.

If you have similar needs, please remember that we can make "simple" modifications without large engineering costs or minimum order requirements. To contact us e-mail jhtek@jhtechnology.com or phone (800) 808-0300 (outside the US, 941-927-0300).

Links: Custom & Special Process Transmitters
JH Technology Web Site: http://www.jhtechnology.com/




Friday, October 30, 2009

Just for Fun - Hallowe'en 2009

HAPPY HOLIDAYS!!!!!

Created by Rick Maccani, our Technical Services Manager - with help from his wife.

For those of you who are "electronically challenged" the symbols are - - eyes=diodes, nose= capacitor, mouth equals resistor.





Saturday, October 24, 2009

Special Modifications

Rapid Increase, Slow Decrease
("Peak Picker")


We've done this for a few customers. The basic application - monitor the peak value of a repetitive signal.
The first application was on an automated machine which formed nail heads. We never saw the machine, but our understanding is that it would "whack" heads on the nails in rapid succession. The user needed to know and control the impact force - not each and every individual impact, but the "normal" or "average" impact. In other words, he needed to know that the machine was properly set.
As the sketch shows, the output rises quickly to the peak value but decays slowly. (Actually, the unit we built had more filtering than is shown in the illustration.) The output of our module smoothed and held the value of the peak impact force.
We've built a few variations on this theme. One had an adjustable decay time (reference - our special feature #X0098) and one had a fixed 3-second time constant (X0214). Right now we're quoting a unit which adds a polarity-insensitive "absolute value" function - both positive and negative peaks will produce a positive output.

Links: Custom & Special Signal Conditioners
Our complete signal conditioner line

Special Modifications

Slow Increase, Rapid Decrease
Just the opposite of the "peak picker".
Application - Heating oven control.
The customer wanted to avoid rapid temperature increases and overheating and so wanted a "slow" filter on the control input. On the other hand, he required a rapid turn-off for fast shutdown. We were able to modify our transmitter's input stage to accomplish this.
(Reference - our special feature #X0251.)

Links: Special & Custom Signal Conditioners
Our complete signal conditioner line

Saturday, October 10, 2009

New Product - Pulse Amplifiers

New Product

Announcement -

Low-Cost

Pulse Amplifiers

We've added two new pulse amplifiers to our product line.

For tachometers, turbine flowmeters and other magnetic coil pickups: Model JH376.

Two channels in one 0.7 in wide case. Each output is jumper-selectable, either 5V pulses or open collector. Highly sensitive, but includes sensitivity adjustments to optimize performance in noisy environments.

To convert logic pulses: Model JH377.

Inputs are jumper-selectable, either 5V/TTL or open-collector/contact closure. Outputs are jumper-selectable, either 5V pulses or open-collector. Again, two channels in one case.

Both products operate from 7 to 24Vdc power and at temperatures from -40 to +80 degrees C (-40 to 176 deg. F).

Links: Pulse Amplifiers and related products
All JH Technology Signal Conditioners

Saturday, October 3, 2009

Absolute Value Function




Absolute Value -

with a difference

(Details on the application mentioned in our September 27 posting.)

A new customer had an urgent need for a signal conditioner (transmitter) with absolute value response. Searching the internet, he read our "Specials & Customs" page and found that we had done this before. His need was different, but we were able to help him.

For those of you who may not be familiar with the absolute value function, it simply ignores the minus sign. The previous special which he found on our web site took a -10 to +10 volt input and created a proportional 0 to +10V output. For example, inputs of either minus 7V or plus 7V created a plus 7V output.

The new customer's application needed a signal representing the temperature deviation from ideal. Ideal temperature produced a 12mA current signal. A deviation, whether positive or negative, required a positive-going output (see graph). At 12mA input the output should be zero percent (4mA). At either 4mA and 20mA (8mA deviation) the output should be 20mA (100%).

We were able to modify the earlier special to accomplish this. As mentioned in our Sept. 27, 2009 post we did some Thursday evening calculations, quoted and took the order on Friday, built 6 units on Saturday (yes - we added an expediting charge) and shipped Monday.

Let us know what we can do for you!

Links: Custom & Special Signal Conditioners
Our home page: http://www.jhtechnology.com/

Wednesday, September 30, 2009

Just for Fun

Sign seen in Sarasota, Florida.

(Sorry - the phone number was distorted to prevent nuisance calls.)





Must it be returned in like-new condition?

Sunday, September 27, 2009

Fast Response - Part 2

Speedy - Part 2

(See August 16 for Part 1)

Part 1 announced fast-response instruments. This time we're promoting our fast response to customer needs.

Thursday afternoon: We received two urgent calls, two different customers, asking "can you do it" and "how fast"? One was for 10 pieces of a standard product; the other, 6 specials which required modest new circuit design. We were able to say "Yes" to both.

Friday morning: Received both orders.

Friday evening: Two of us (Rick & Harry) stayed late.

Saturday: Rick & Harry worked from about 8:00 until 2:45PM. Finished both orders.

Monday: Both orders shipped. (Of course, both customers paid expediting charges to cover our overtime.)

Details: The standard-product order (JH4001I RTD Transmitters) was from a Navy base. They had been using "Brand A" products but that company was not able to delivery quickly. They sent searching and found us on the web. We did not have any in stock either - so we worked the weekend!

The special requirement was for an absolute-value transmitter. (See our posting of October 3, 2009 for more detail.) We had done this before (as a special in 2001) but the detailed requirements were different on this time. Thursday evening calculations plus weekend assembly and test got the job done.

Conclusion: If you need action, call us.

(800) 808-0300 or (941) 927-0300. e-mail jhtek@jhtechnology.com

Tuesday, August 25, 2009

GSA????

GSA - General Services Administration

One of our government customers (with the US Bureau of Reclamation) was disappointed he could not simply order one of our products through the GSA - told us we're making things difficult for him. Since we pride ourselves on making things easy - and of course would like more government orders - we've decided to learn how to get listed.

We've been approached by consulting companies who can get us started for several thousand dollars (more to follow???) but since we're small, we decided try it on our own first. If we then need help, at least we'll know the questions to ask!

We've learned on our own before, for the Navy. (See blog dated June 8, 2009.) Conquered WAWF (Wide Area Work Flow), CCR (Central Contract Registration), SBA (Small Business Administration) etc. A few headaches along the way, but we made it. And, free help was usually available via US government toll-free numbers.

(Personal comment: despite all the criticism we hear about government employees I've found the majority of them to be courteous and helpful, limited perhaps by the bureaucratic systems they work in.)

It looks like a good amount of help is available from the GSA. We're already signed up for a free GSA web seminar in September.

Stay tuned - or better yet, if you have some helpful hints, please let us know. (E-mail jhtek@jhtechnology.com, or just comment here, or US toll free 800-808-0300).

Sunday, August 16, 2009

Fast Response


Speedy!

OK - maybe you're expecting me to promote our fast response to your orders. (Sneaky how I worked that in!)
The real topic - fast-responding signal conditioners.
A few months ago a customer asked if we could provide frequency response to at least a few kilohertz for DC and load cell signals. Our standard circuitry could not. His quantity requirements were large enough that we designed a new circuit to meet his needs (3kHz minimum). We've since shipped his order. He tells it is working well in his application - heavy-duty shock testing. More recently another customer needed just three fast-response units which we now are able to easily supply.
We're working on the paperwork and documentation to turn this in to a standard catalog product line of DIN-rail mount transmitters. Look for it shortly.
Meanwhile, if you have high-frequency or fast-response requirements, please ask us. E-mail jhtek@jhtechnology.com or call (800) 808-0300 (US toll-free) or (941) 927-0300.

Link to Fast Response Process Transmitters

Wednesday, August 12, 2009

Extended Temperature Operation





Too Hot? --- Too Cold?



Wouldn't you know - while this job was in progress we had another customer who needed to operate at high temperatures in a solar energy monitoring application. Same exact product (JH4380W), same exact solution. The extended temperature ICs support a temperature range of -40 to +85 degrees C (-40 to +185 degrees F).

We recently took an order (almost ready to ship as this is written) for 54 rangeable transmitters (JH4380W) to operate in environments as cold as minus 40 degrees (C or F - this is the one point on the temperature scale where both are the same). Our customer tells us the end destination is Russia. No great technological challenge - we simply built a run using extended-temperature ICs.

Link to our Specials & Customs page
Home page - all Process Transmitters & Alarms

Saturday, June 13, 2009

Just for fun

BLATANT NEPOTISM!


Harry again. No technology this week. Instead, I'm bragging about our older daughter's web site. Lisa is a full-time nurse but also very talented at sewing, quilting, cross-stitch etc. After a number of requests from friends she decided to turn it into a part-time, web-based business, Heatherfish Studios. Named after her daughter (our granddaughter) Heather, who swims like a fish.

Here are a few samples: a Tote Bag, a children's Crayon Roll and a set of Coasters.




Like JH Technology hers is a small business, flexible and she has fun with it. And, like JH Technology, special orders are no problem.

OK, enough nepotism. If you're interested -





Monday, June 8, 2009

Supporting the Navy

The US Navy, directly and indirectly, represents about 15% of our business. Here's what we do for them.

Standard Products - we sell standard products to a major servicer/supplier to Navy ships and, sometimes, direct to the ships themselves. It's fun to get e-mails and satellite calls from ships, followed by orders for intruments to be delivered to places like Hawaii and Singapore.

They mostly use our plug-in style transmitter and alarm modules because they stay in place well with ship motion and vibration. The most common styles are temperature transmitters (temperature input, DC voltage or current output) and alarm trips, frequency to DC converters and DC to freqiuency converters. We've sometimes done beefed-up specials for best possible assurance that they will survive mechanical stress.


Custom Products - Several years ago we developed a pulse conditioner to meet Navy requirements. Its function - convert a pulse train of almost any amplitude and waveshape, from millivolts to over 100 volts, square wave, sine wve or other, and convert it to a clean, isolated 5V logic pulse output. We don't know the Navy's application, but they've ordered many through contractors over the years.



Minisystems - We often take one or more of our products, sometimes together with products from other companies, and create "Minisystems" to meet customer's unique needs.

This one took our standard RTD (Temperature - Resistance Thermometer Input) transmitter, added a cable and connected it to a display board that we normally use in our Field-Mount transmitters. The US Naval Air Warfare Center, Lakehurst, NJ, needed a number of these to amplify and display temperatures as part of a system to test and certify steam cylinders used to catapult airplanes from Navy aircraft carriers.

We discussed various enclosure styles, but the Navy personnel decided they would rather just buy the "innards" from us and design them into their test system. Must have worked - they later bought a second round.

Part of our first shipment, on overnight burn-in test.


For more on our customs and specials capabilities: www.jhtechnology.com/customs. Or, of course, call (800) 808-0300, (941) 927-0300 or e-mail jhtek@jhtechnology.com

Sunday, May 31, 2009

Just for fun

AFFORDABLE HOUSING!


Just for fun - actually from 2005 when house prices were escalating upward.

Our good friends in Charlotte had just signed for a new townhouse in Fort Mill, South Carolina. They took us to see the construction site and this is what we found on their lot.

Monday, May 25, 2009

Minisystem Controls Blending (Flow) Ratios

A very simple "system", but it solved our customer's problem.

The need: our customer needed a simple way to control the blending proportion (ratio) between two pump flows. The user desired a ratio adjustable from 1:5 to 5:1, with the center of the adjustment range being 1:1.

The pump controller's input was a standard 4-20mA dc control signal (4mA produces zero flow, 2o mA produces maximum). Our system needed to take the input (flow #1), multiply it by the ratio and produce an appropriate 4-20mA output (flow #2).
The solution: our JH4410 multiplier module plus a 10-turn precision potentiometer. The JH4410 was modified so that input B was the potentiometer's position. (Input A was set up for standard 4-20mA input.) The output's 4-20mA signal was proportional to input A multiplied by the potentiometer position. Additional modifications created the desired dial settings - 1:5 (gain = 0.2) at zero turns, 1:1 at five turns and 5:1 (gain = 5) at 10 turns.
At the customer's request the system was mounted in a wall-mount industrial enclosure.
For other examples of our custom & Minisystem solutions visit www.jhtechnology.com/customs.

Sunday, May 17, 2009

Thermistors for Temperature Measurement

Thermistors for industrial temperature measurements? Sure - we just took a repeat order from an OEM customer (for instruments - we don't sell the thermistors themselves). So, I thought I'd write about them.

Let me identify myself - Harry Trietley, President & Chief Engineer. In the 1980s I worked at YSI (formerly Yellow Springs Instruments) who had once pioneered precision interchangeable thermistors. (They no longer make them - sold the product line off.) So, I had the opportunity to learn how to apply them. We now have two regular OEM customers.

You won't find thermistor info on our web site - maybe we should add it. For now, this blog is a start.

Thermistors are resistance thermometers but much different from RTDs (Resistance Temperature Detectors). RTDs are linear (approximately), wide range, relatively low sensitivity (about 0.4% per deg C) and increase with temperature. Thermistors are highly nonlinear, narrow range, high sensitivity and decrease with temperature (about 4% per deg C).

There are many types of thermistors - small, large, highly accurate, loose accuracy, many shapes. This blog is about NTC (Negative Temperature Coefficient) thermistors. There also are PTC (Positive Temperature Coefficient) thermistors that act more like thermal switches - increasing resistance rapidly in just a few degrees near the switching point. PTCs are not used for linear temperature measurement.

Precision NTC thermistors excel in moderate temperature, narrow range applications. They are very sensitive, and some have tighter accuracy specs than RTDs. One of our customers uses them in heating/air conditioning control; the other, precision measurements related to integrated circuit manufacturing processes. They also see wide use in medical and laboratory temperature measurement.

We have made simple adaptations of our signal conditioners (temperature transmitters) for use with thermistors. So far we haven't published standard spec sheets, but they are very similar to our other instrument styles. (See http://www.jhtechnology.com/).

If you have an application let us know. Each application is different as there are many thermistor types. We would need to start by knowing your measurement temperature range - also the thermistor type if you have chosen one yet. If not, we can help you find the right one. Probably best to ask for Harry.

e-mail: jhtek@jhtechnology.com, US phone (941) 927-0300 or toll-free (800) 808-0300.

Sunday, May 10, 2009

Split 4-20mA Loops without a Loop Splitter

Save money! Don't buy a loop splitter if you don't need one.

Users often specify dual-output 4-2omA current loop splitters in their systems. Common reasons include:

  • The need for an output boost to drive several loads at once.

  • The need to run independent isolated current loops to two different systems.

These needs often can be met with a less-expensive single-loop isolator. The diagram shows the basic idea - use the source transmitter to drive the isolator's input plus the first loop, then use the isolator's output to drive the second loop.
















For our complete application note (pdf) click here , or visit http://www.jhtechnology.com/ and click on the Application Notes link.

Saturday, May 9, 2009

Hello, visitors

We've only just begun .... A brand-new blog.

JH Technology, Inc. is an electronics company - we manufacture instruments known as signal conditioners, used mostly in industrial measurement and control applications. What is a signal conditioner? It's an amplifier for measurement signals. Signal conditioners amplify and convert signals such as temperature measurement (thermocouples, resistance thermometers and thermistors), pressure, force and weight (strain gauges, load cells), position (potentiometers), speed and RPM (tachometer pulses) and others. We don't make the sensors themselves, but we amplify and convert their signals.

We're a small, engineering-driven company and have strong capabilities in specials and custom or OEM products. We're also a bit old-fashioned - we answer the phone instead of running you around in circles with voice mail. We're proud of our customer service. If you need application assistance, have odd requirements or just need fast delivery, give us a try!

More "blogging" to come. Meanwhile, if you're interested, please visit us at http://www.jhtechnology.com/. To learn more about our specials and customs capabilities, visit www.jhtechnology.com/customs.

Of course, feel free to call:

Toll-free in the US (800) 808-0300
(941) 927-0300.