JY44 DC bridge is a high-precision, portable resistance measuring instrument designed based on the Wheatstone bridge principle, suitable for precise measurement of median resistance in laboratories, factories, and on-site maintenance. Its measurement accuracy is high and stability is good, but correct operation is a prerequisite for obtaining reliable data. This article will provide a detailed explanation of its usage and precautions.

1、 Usage method

1. Preparation: Place the bridge horizontally on a stable and vibration free surface. Open the battery compartment cover and insert the specified model of dry battery, paying attention to the positive and negative pole directions. If using an external power supply, ensure that its voltage is stable and meets the requirements of the instrument.

2. Connect the tested resistor: Use high-quality measuring wires to reliably connect the tested resistor Rx to the "Rx" terminal of the bridge. Ensure good contact at the connection points, without oxidation or looseness. For low resistance measurements, the length of the wire should be shortened as much as possible and the contact resistance should be reduced.

3. Choose the appropriate magnification: Based on the estimated resistance of Rx, use the "magnification" knob to select a suitable magnification. The selection principle is to ensure that all four reading disks of the "proportional arm" can effectively participate in the adjustment during measurement. Usually, the i-th reading disk should not be zero to obtain the most significant digits and the highest accuracy.

4. Adjust the balance of the bridge:

Press the 'B' button first to connect the working power supply of the bridge.

Then intermittently press the 'G' button while observing the deflection direction of the ammeter pointer.

Adjust the four reading disks in sequence to gradually reduce the deflection amplitude of the pointer. Fine tune in the order of 'high to low' until the ammeter pointer points to zero when the 'G' button is pressed.

5. Reading and Calculation: When the bridge is balanced, the resistance value of the measured resistor is determined by the formula: Rx=multiplication factor x reading dial reading. The reading panel indicates the sum of the four panel readings.

6. Measurement completed: First disconnect the "G" button, then disconnect the "B" button, and finally remove the measured resistor. This operation sequence can avoid the impact on the current meter during sudden changes in current.

2、 Precautions

1. Battery power: if the galvanometer pointer of each reading panel does not respond after pressing the "B" button, first check whether the battery power is exhausted.

2. Button operation: The time for pressing the "G" button should be short, especially when the pointer deflection angle is large, to prevent excessive current from passing through the ammeter. Suggest using the 'jump connection method'.

3. Equipment maintenance: When not in use for a long time, the internal battery should be removed to prevent battery leakage and corrosion of the instrument. The instrument should be stored in a dry, dust-free, non corrosive gas, and suitable temperature environment.

In summary, the JY44 DC bridge is a precision instrument that embodies classic measurement wisdom. Mastering the correct operating steps and maintenance essentials can not only obtain accurate measurement results, but also extend the service life of the equipment. Rigorous operation is the cornerstone of precision measurement.