What it is

Family Type 8742A are quartz shock accelerometers for measuring impulse, impact, and pyrotechnic shock.

The Kistler 8742A is a quartz shear shock accelerometer for short-duration impulse and impact shock from ±5,000 to ±50,000 g. It has a nominal mounted resonant frequency of 100 kHz and a 1 … 10,000 Hz (±7%) frequency response. Built-in Piezotron electronics give a low-impedance voltage output, and a welded case with integral 10-32 stud mounts it rigidly.

• Four ranges: ±5,000, ±10,000, ±20,000, and ±50,000 g
• Resonant frequency: 100 kHz mounted, nominal
• Frequency response: 1 … 10,000 Hz (±7%)
• Quartz shear element: quartz does not depolarize under high shock
• Low transverse sensitivity: 1.5% typical, 5% max.
• Low-impedance voltage output: <100 Ω, ±5 V full scale
• Rugged connector: gold-plated beryllium-copper spring insert for repeated connections
• Conforming to CE

What it is used for

Some of the use cases for the 8742A include:

• Impact and impulse shock — where metal-to-metal impact occurs
• Drop shock — package and product survivability tests
• Vehicle crash — crash data collection

Main features / advantages

What does the 8742A measure?

The 8742A family are quartz shock accelerometers for measuring short-duration impulse and impact shock.

The sensing element contained within this shock accelerometer series features a unique shear-mode, four-quartz-crystal configuration combined with an annular preload sleeve and seismic mass. The element design provides a resonance frequency above 100 kHz, ensuring accurate measurement of high-speed events with zero shift and internal amplifier saturation virtually eliminated. These shock sensors exhibit insensitivity to thermal transients with extremely low transverse and base strain sensitivity. Using quartz as the sensing material adds a valuable performance benefit, because quartz will not depolarize if exposed to high shock.

An internal microelectronic Piezotron signal conditioning circuit converts the charge developed in the quartz element into a usable high-level voltage output at low impedance, giving high immunity to noise and insensitivity to cable motion.

Why engineers pick it

• Quartz survives the shock. Quartz will not depolarize when exposed to high shock, and the 8742A50 carries a 100,000 gpk shock limit.
• No zero shift. The shear-mode, four-crystal element with over 100 kHz resonance virtually eliminates zero shift and internal amplifier saturation on high-speed events.
• Connections that don't drop out. A gold-plated beryllium-copper spring insert in the connector promotes positive pin contact and resists aging, so an applied shock does not interrupt the measured event.
• Low noise into long cables. The low-impedance output (<100 Ω) gives high noise immunity and insensitivity to cable motion.

Which 8742A range do I need?

Choose the lowest range that covers the expected peak. Each step up in range lowers sensitivity and raises the threshold in proportion.

How is the 8742A mounted?

The 8742A attaches to the test structure with its integral 10-32 UNF-2A stud, tightened to 18 lbf·in (2 N·m). The mounting surface must be clean and flat. For ground isolation, use base Type 8466K06 when stud mounted or pad Type 8436 when adhesive mounted.

The measuring chain is a Type 1761B… sensor cable (10-32 pos. to BNC pos.), a Type 51… power supply/signal conditioner, and a Type 1511 BNC output cable.

When is the 8742A the wrong choice?

• Low-level vibration. With a threshold of 0.13 grms on the most sensitive range and sensitivity of 1 mV/g or less, the 8742A is built for high-g shock, not general vibration.
• Long-duration or very low-frequency signals. The time constant is ≥0.5 s and the frequency response starts at 1 Hz.
• Ranges above ±50,000 g. The 8742A tops out at ±50,000 g.

Configure and order the 8742A

Choose the 8742A range and cable your test needs and order directly on this page. For questions, contact us.