| Specifications | AN103C |
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| Specifications | AN103C |
| Business section |
| Specifications | AN103C |
| Suggested Link Details/Purchase | |
| Content | Application Note AN103C www.hamlin.com © 2007 Hamlin Electronics L. P. p 4/4 1. Manual Ramp, Manual Read Method. For this method, the coil voltage or current is slowly increased by hand using an adjustable power supply or other control circuit. When a meter, beeper, or light indicates that the switch closes, the ramping of the coil is stopped and the coil current is measured using a current meter installed in series with the coil. The response time of the person performing the test is a significant factor in limiting the accuracy of this manual method. Using a slower DMM to monitor the switch closure can also be a factor. 2. Manual Ramp, Sample & Hold Method. As above, the coil is manually ramped. However, when the switch closes, it triggers a circuit or instrument that quickly records the coil current. A common circuit for accomplishing this is called a Sample & Hold circuit. Such a circuit would sample the coil current while ramping, perhaps by measuring the voltage across a resistor in series with the coil. When the switch closes, the circuit would hold the sampled value on a low leakage capacitor for example. This method has the advantage of removing the variation resulting from a person responding to the switch closure, but this method still involves manual coil ramping. 3. Automatic Ramp, Manual Read Method. In this method, ramping of the coil current is done using a circuit such as a digital circuit controlling a DAC (Digital-to-Analog Converter) or an analog circuit based on charging a capacitor. When the switch closes, circuitry can stop the ramp circuit very quickly. Then, the coil current can be measured in a leisurely fashion. Like the previous method, the variation of a person’s response time is removed, but also the ramp rate is controlled. 4. Automatic Ramp, Automatic Read Method. As in the previous method, the coil is ramped using a circuit, preferably digitally controlled. In addition, a microprocessor or other control circuit controls the measurement of the coil current so that the entire test sequence waveform shown above is automatically carried out in a repeatable manner. This has the advantages of decreasing the test time and improving measurement repeatability and accuracy. |
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| Following Datasheets | AN104 (2 pages) AN105A-Tech-Extended_Temperature_Operation (6 pages) AN107-Capacitive_Loads (1 pages) AN110A-Tech-Reed_Switch_Selector_Guide (3 pages) AN111A-Tech-Shock (1 pages) AN113A-Tech-Vibration (1 pages) AN115-Tech-Soldering_Temperatures (1 pages) AN121-Storage (1 pages) an605cn (4 pages) an608-cn (6 pages) |
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