1615-A

The General Radio 1615-A Capacitance Bridge was introduced in Catalog R (1963) and remained available through Catalog 1978.

The Type 1615-A is a laboratory-grade capacitance bridge with an accuracy of ±.01%. It uses a specially designed transformer as part of the bridge circuit. The transformer's primary, connected to the generator terminals, supplies power to the bridge. Tapped secondary windings comprise two arms of the bridge. The tapped side of the transformer along with capacitance standards comprise one arm of the bridge circuit, the opposite side is in series with the unknown. Eight capacitance standards are housed in a sealed nitrogen filled container. This design enables the high performance of this bridge and stability of its measurements.

Balancing the bridge for capacitance is performed using six lever-type switches with twelve positions each, plus a range switch. This creates a 6-digit display in windows above of the measured capacitance with automatic decimal point placement. Dissipation factor or conductance are entered in a similar way, with four switches and a 4-digit display with the decimal point automatically placed according to the range switch position.

The 1615-A measures two- or three-terminal capacitances, selected by a panel switch using two sets of connectors, with three-terminal using two coaxial connectors or three binding posts, and two-terminal measurements with two binding posts. This switch also updates the simplified schematic engraved on the panel and has a position to enable a calibrate function. There's a small removable access panel covering the calibration adjustments.

An accessory, Type 1615-P1 Range Extension Capacitor was available that extends the upper limit to 11.11110 μF, and the Type 1615-P2 Coaxial Adapter converts two-terminal binding posts to the GR900 system.

Specifications

• Ranges Of Measurement
• Capacitance: 10⁻¹⁷ F (10 aF or "μpF") to 1.11110 μF in 6 ranges
• Dissipation-Factor: 0.000001 to 1 at 1 kHz in 3 ranges
• Conductance: 2 ranges; See manual
• Accuracy: ±0.01%
• Frequency: Approximately 50 Hz to 10 kHz, with reduced accuracy to 100 kHz

Links

• The General Radio 1620-A Capacitance-Measurement Assembly combines a 1615-A with a Type 1240-A Oscillator/Null Detector (1311-A Bridge Oscillator + 1232-A Null Detector)
• Experimenter August 1962 describing Type 1615-A
• Experimenter February 1963 describing Type 1615-P1

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