Designer's corner 843

DN Staff

August 11, 1997

3 Min Read
Designer's corner

Tissue strain sensor

Two hermetically sealed coils, excited by a 70 kHz voltage, make up this push-pull Differential Variable Reluctance Transducer (DVRT). A ferrite core, housed in a super-elastic Nitinol(R) core, moves between the coils. Zero voltage output (null) occurs when the plunger rests at the center position.

Designed to measure strain in ligaments and other soft tissues, the DVRT can be used in moist or hot environments.

As the core moves coil inductance changes. This change, transformed into plus or minus 4 dc voltage using a synchronous sinewave oscillator and demodulator, indicates direction and distance of core movement.

Microminiature DVRTs can provide linear strokes of 1.5, 3, 6, and 9 mm. Resolution equals 1.5 mum; a high-resolution version provides 60 nm resolution.

MicroStrain, 294 North Winooski Avenue, Burlington, VT 05401.


Clear-view flow indicator

By looking through a clear polysulfone window on one side of this indicator and watching a rotor spin, you can verify that flow is taking place and estimate flow rate. With practice, users can determine approximate flow rates to a maximum of 10 gpm. FlowSure(R) has a glass-filled polypropylene body and a polypropylene rotor. Rated for 180F (continuous) the unit can withstand pressures to 100 psi.

Spinning rotor of the FlowSure indicates flow and enables machine operators to make a quick estimate of flow rate.

Harkness Technologies, 50 Grandview Court, Cheshire, CT 06410, 800-343-4275.


Multilayer-backpanel pin

When the one-piece PONY PIN(R) plugs into a standard 0.030 plus or minus 0.003-inch-diameter plated thru hole, its "C"-shaped cross-section tail forms a gas-tight connection. The pin can accept a variety of leads, from 0.016-inch diameter leads to 0.025-inch square posts. Especially suitable for multilayer backpanels, the BeCu PONY PIN has a 0.062-inch-diameter head and reportedly fits all standard plastic headers, DIP and SIP sockets.

Designed to measure strain in ligaments and other soft tissues, the DVRT can be used in moist or hot environments.

ELPAKCO INC., 2 Carl Thompson Road, Westford, MA 01886, 508-392-0400.


Solder delivery array

Flexible solder array carriers permit assembly of both through-hole and surface-mount components on the same PC board in one reflow process. Predefined solder blocks or rings are attached to the carriers. Flux dipping and heat application melts the solder, releasing the carriers, which users can then pull out and reload with solder.

Designed to measure strain in ligaments and other soft tissues, the DVRT can be used in moist or hot environments.

ULTRA FINE ASSEMBLY, 2066 Verbena Court, Fremont, CA 94539, 510-659-1088.

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