In the event of your unit being non-repairable and you decide to purchase a replacement unit, we will assume you do not want your original unit shipped back to you. If you do want the original part returned, then it will be your responsibility to inform us and accept the additional shipping charges.
Our preferred method of shipping for available locations in the Midwest. Spee-Dee provides overnight shipping for most locations at a reasonable cost. In more rural areas, shipping is generally between days instead. If you are within the Spee-Dee service area, then this option will be available for you.
Estimated delivery times of 5 business days or less. For select areas on the West Coast, this can extend to business days. Skip to content. Also, quite often DigiKey has a huge stock of Obsolete components. You are better to check manufacturer for product life status. With DigiKey you are correct, i meant to say when they have a huge stock I feel more comfortable. Right now other companies do not even have a stock, even manufacturer, so I thought to look at other solutions before committing.
The manufacturers usually build them in batches rather than setting up a continuous line. If this design is for a product, then your "due diligence" is to contact the manufacturer directly to see if this product is slated for the archives yet.
They may even have a newer, as yet unpublished, version they intend to replace it with. Show 1 more comment. Active Oldest Votes. Spehro Pefhany Spehro Pefhany k 12 12 gold badges silver badges bronze badges. The OnSemi part though is for Speedo frequency input, I need more freedom by sending data serially, albeit that can be tricked by generating a frequency - dirty solution but functional. Add a comment. Assuming an orthogonal orientation of the coils, a given deflection DEFL with respect to a vertical axis is achieved with a vertical coil current proportional to cos DEFL and a horizontal coil current proportional to sin DEFL.
By providing for bidirectional current, deflections of up to degrees may be achieved. The present invention is directed to a control arrangement including a computer-based controller and bipolar driver for bidirectional current control of air core gauge coils by pulse-width-modulation PWM of a DC source.
The computer-based controller processes input information in the form of a frequency, analog voltage, etc. The control signal is generated in the format of a bipolar PWM duty cycle and the bipolar driver applies the voltage of the source to the coils in alternating polarity in accordance with the duty cycle of the control signal.
The term DELTA is defined in relation to the time required by the control unit to receive and process the input data and may also be scheduled to regulate the magnitude of the resultant magnetic field vector and thus the pointer alignment torque. The latter point is significant because generation of very low and very high duty cycles is typically difficult to harmonize with the processing duties of computer-based controllers.
With the arrangement of this invention, a single computer-based controller can control several gauges, limited only by the processing requirements, the throughput capability of the controller and hardware limitations, if any. Referring to the drawings, and more particularly to FIG. Each coil X, Y generates a magnetic field vector B x , B y in relation to the magnitude and direction of current therein. The two field vectors B x , B y combine to produce a resultant magnetic field vector B res which correspondingly deflects a rotor magnet assembly not shown attached to the pointer.
On a linear scale of deflection, the current supplied to the Y coil is scheduled in relation to the cosine of the angle DEFL, designated by the trace The current supplied to the X coil, on the other hand, is scheduled in relation to the sine of the angle DEFL, designated by the trace Thus, any controller of an air core gauge must be capable of determining the sine and cosine of the desired angle of deflection and supplying corresponding currents to the coils X and Y. The relative magnitudes and directions of the currents in coils X and Y determine the direction of the resultant magnetic field vector B res and hence the pointer deflection.
Variations in the absolute magnitudes of the currents as due to power supply variations affect only the magnitude of the resultant magnetic field vector B res which pertains to the pointer aligning torque.
In digital control, current regulation is conveniently mechanized by pulse-width-modulation PWM of the applied voltage. As depicted in the graph of FIG. The PWM driver in such arrangement may be a conventional bridge, commonly referred to as an H-switch. Positive current corresponds to positive duty cycle; negative current corresponds to negative duty cycle.
As in FIG. The control arrangement described above is conveniently mechanized with a dedicated digital logic circuit due to its parallel processing capability. One part of the circuit can be processing input data while another part processes output data.
However, problems are encountered in computer-based mechanizations due to the limitations of serial processing. For example, frequency inputs such as for vehicle or engine speed are typically decoded by counting the output pulses of a relatively high frequency free running oscillator between pulses of the lower frequency input, such count being inversely related to the sensed speed.
To avoid the use of external circuitry, such processing is normally carried out by the computer, using its interrupt capability. In other words, each leading or trailing edge of the input data signals the computer-based controller to interrupt its current duties to process the input data. Servicing of such interrupts creates what is commonly known as interrupt latency, which potentially increases the time required for the computer to perform any regularly scheduled task, such as outputting PWM data.
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