Most of our product designs are modular - separate input, output and power subassemblies. These assemblies can be interchanged and, usually, easily modified.

Often, your needs can be met by simple internal modifications - change a resistor or two, cut a circuit trace, add a jumper etc. Such modifications have little impact on price or delivery, even on one-piece orders.

There's nothing "standard" about our specials. We've quoted over 200 so far. Many have been sold repeatedly - some to multiple customers, others as OEM designs. Others were one-time, one-piece orders to meet specific needs.

Examples follow. Whether your need is on this list or is new and different, contact us to discuss your requirements.
 
SPECIALS WE HAVE DONE

More Filtering. Our instruments normally include modest filtering to minimize AC and noise pickup. Some systems need heavy filtering to smooth or average noisy or varying signals. We've added increased filtering - both fixed and user-adjustable - providing time constants up to 30 seconds.

Less Filtering - Fast Response. Sometimes filtering must be reduced or eliminated to monitor rapidly-changing signals. Applications have included measuring voltage and pressure transients, rapid temperature changes and projectile impact force.

Fast Rise, Slow Decay. To capture the peaks of transient signals we've added fast-rise, slow-decay response. For regularly repeating periodic signals the output approximates the peak value. For one-time pulses the slow decay (3 second time constant) allows the peak to be observed or captured.

Delayed Alarm Trip. To avoid false trips due to momentary transients, the alarm will not trip unless the signal remains out-of-bounds longer than the delay time. We've added fixed and adjustable delays up to 30 seconds.

Wide Adjustment Range. Most of our fixed-range transmitters provide fine adjustment of zero and span, about +/-15%. Some applications need more. We've done a number of modifications to allow wider zero, span or both. The tradeoff - a reduction in adjustment resolution, making it more difficult to adjust to 0.1% or better.

Remote Adjustments. We've replaced the built-in trimpots with remote adjustments for zero, span and/or alarm trip points.

Nonstandard Input Ranges. Our standard catalog capabilities allow a wide variety of range possibilities but sometimes people need more - or less.  We've modified instruments to allow inputs up to 600 volts AC and DC, up to 10 amps and down to just a few millivolts.  We've also made changes to accept lower-than-standard temperature ranges.

Nonstandard Output Ranges. Some applications need outputs beyond our standard catalog capabilities. We've provided 10-50mA and beyond, and voltages to plus or minus 25V. We've also provided output spans below our standard minimums of 1 volt or 1 mA.

Max/Min Output Limiters. Most applications want to know when an input goes over- or under-range. Some, however, need firm limits to avoid false alarms or overdriving A/D converters or receiving instruments. We've added circuitry to limit both overrange and underrange outputs.

Unique Math Functions. Our standard products provide add, subtract, multiply and divide functions. Square and square root, although no longer in our catalog, are still available. We've also provided 6-input summers (our standard limit is 4), unequal input ranges on math units, absolute value, absolute value subtractors and a summer with an adjustable scale factor on one input. And we've even built an AxB/C function.

Contact Closure (On-Off) Inputs. In one application we modified our single alarm trip to trip upon contact closure and reset when the contact opened. In another we provided a transmitter whose output toggled between two preset values, one for open, another for closed.

Increased Ambient Temperature Range. We've provided extended operating range by assembling otherwise-standard products using extended-temperature ICs.

High Input Impedance. We've modified standard transmitters (voltage input) for 10 and 20 megohm impedance and built a custom buffer with 100 megohm impedance.

Nonstandard Pin or Terminal Connections. Occasionally, people need replacements for plug-in modules having pin connections different from ours. No problem -we'll rewire to your needs.

Restricted Access to Adjustments. Our trimpot adjustments normally are accessible. When you need to restrict unauthorized access we'll cover them. Recalibration requires opening the enclosure.

Frequency Input Transmitter with Unique Functions. To work with a specific Brooks Optoturbine flowmeter we needed to supply regulated 8.2 V to the turbine and receive current pulses varying between 1.2 and 2.1 mA.  A modified JH7010 frequency transmitter produced a 4-20 mA flow rate output.

Transmitter for Two Input Ranges. The customer needed true-RMS measurement on two different high-voltage ranges. We modified our circuit and added connections such that one set of input terminals provided a 0-250Vac range; the other, 0-480V.

Alarm with Unique Functions. This OEM special provided a single-trip alarm with 0-5 volt retransmitting output, fast response and delayed reset.

4-20mA Output Compatible with 120Vdc Loop Power. Most of our transmitters offer a Loop Powered Output option (LPO). This allows our AC-powered transmitters to be safely connected to PLCs and other systems whose inputs include 24V loop excitation. One customer's unique application required 120Vdc loop excitation, not 24V. We did it.

RTD Alarm with Adjustable Excitation Current (30mA max). A very unique test application using a 500 ohm platinum RTD (resistance thermometer). Normally the RTD current is kept very low to minimize self-heating errors. This test application, though, needed the excitation to be adjustable from 1 to 30mAdc.