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Strain indicator A manual di g ital strain indicator and a five-channel
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switch-and-balance unit have been announced by Welwyn Electric Ltd. The Bean Model 201 strain indicator is a null-balance instrument that is equipped with a d.c. bridge-energization system and has ap amplified dynamic output connected to alp external recorder or oscilloscope, the frequency response being up to 20kHz. A battery life of up to 400h enables the instrument to be offered as an easily portable unit. Known as the Model 301, the switchand-balance unit has a balance range of 5,000 microstrain in each channel, while the switch is a multiple, six-position militarygrade type. A carrying case is available that can accommodate one 201 and one 301 unit, the weight of the complete five-channel system being under 71b. Marketed by: Welwyn Electric Ltd., Strain Measurement and Equipment Division, 70 High Street, Teddington, Middlesex.