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The BCAL-1 and the BCAL-2 Cement Bond Tool (CBT) Calibration Circuit printed circuit boards (PCBs) are suitable for use in many different cement bond logging tools. A downhole switchable calibration circuit is a desirable addition to any cement bond logging tool. A calibration circuit is especially useful in wells lacking free pipe (wells "cemented top to bottom") where log set-up is otherwise more difficult. The conventional arrangement is for the calibration circuit to be switched to the receiver amplifier input on slight over-voltage for an instant (130 or 140 volts does not hurt the tool electronics for that brief time), and the normal receiver input is switched back on application of negative line power for an instant (again, no harm is done to the tool electronics due to diode protection).
The BCAL-1 Calibration Circuit PCB is a variation of the CRC / Western true sine wave bond tool calibrator. This ingenious little circuit uses a tuned inductor to produce a ringing sine waveform for calibration. The result is a calibration circuit less sensitive to line length variations, and a calibration signal that looks more like a real bond log receiver signal. The frequency of the sine wave is selectable to match tool response (most larger single and dual receiver bond tools operate at 20 kHz). Signal delay / position timing resistor R4 and gain range setting resistor R6 are turret terminal mounted for ease of selection or change on a fastened board. The BCAL-1 PCB is jumper configurable to be compatible with either armor / chassis negative or armor / chassis positive line power. It requires only a connection to line and a single 10-15 volt power supply to operate, and can be powered directly from our BAMP-1 or 4091 Cement Bond Tool Amplifiers. The BCAL-1 PCB measures 0.8 inches wide and mounts on three (3) inch centers.
The BCAL-2 Calibration Circuit PCB is a traditional pulse type bond tool calibrator, but is greatly improved over the old SIE / Computalog design. The circuit is essentially the same as BCAL-1, but with the omission of the ringing inductor. Signal delay / position timing resistor R4, pulse width timing resistor R5, and gain range setting resistor R6 are turret terminal mounted for ease of selection or change on a fastened board. The BCAL-2 PCB is jumper configurable to be compatible with either armor / chassis negative or armor / chassis positive line power. It requires only a connection to line and a single 10-15 volt power supply to operate, and can be powered directly from our BAMP-1 or 4091 Cement Bond Tool Amplifiers. The BCAL-2 PCB measures 0.8 inches wide and mounts on three (3) inch centers.
The BCAL-1 and BCAL-2 Cement Bond Tool Calibration Circuit PCBs can be used to upgrade tools, or they can be used in new tool construction. These boards use readily obtainable components, which parts will continue to be available for many years to come, and they use convenient turret terminals for wiring connections.
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