Dave wrote on 11/8/2019 4:30 PM:
Donald,
? Thanks for confirming what I thought. That makes sense. This is a self resetting fuse. I guess I can test the parts with heat and see what they cool down to after they have been tripped using a hot air gun or oven. I am hoping in normal use they stay a 1.5 ohms and only in the case of a short they quickly ramp up to trip and cool back down to 1.5 ohms. Then I can just make a minor adjustment in my resistor specs.
Dave
Hello, Dave--
It should be possible to create a more elaborate test.? The basic idea is to explore the DUT's
recovery time and series resistance.
Connect the device under test (DUT) in series with a regulated power supply. On the
downstream side, connect a SPDT switch to two load resistors. One resistor represents a normal load (e.g., 100 ohms). The second resistor represents an
overload condition,?? for example one tenth of the nominal load resistance (e.g., 10 ohms).
Measure the power supply voltage (say, 10 volts). If you're uncertain about the power-supply
regulation, connect an ammeter in series with the output.
Connect a voltmeter across the DUT.
Measure the voltage drop across the DUT with the switch set to nominal load.
Switch to the overload resistor and measure the voltage drop across the DUT.
Switch to the nominal load resistor and observe the voltage drop across the DUT
until (or if) the voltage drop returns to its previous value.
Modify the test values to suit your actual load conditions. Be prepared to
release magick smoke from a DUT or two<g>.
73--
Brad? AA1IP
