The power dissipated inside the resistor is equivalent to the voltage drop across the resistor multiplied by Imax
In figure 2 we have standard zener diode test circuit. The ammeter (Am1) is in collection with R1 and D1 and linked to some 0 to twenty volt (sure use 0 to twenty volts) variable DC power provide. For this test I’ve selected for D1 a 1N5342B 13 volt zener diode. (Range 12.35 to 13.65 volts) The diode has a power dissipation of 500 mW max and an Izt of 9.5 mA. I’ll assume 10 mA for Izt.
Initially 1 must give consideration to the power dissipation with the zener diode. To get the utmost current by means of the actual zener diode we must divide the zener power rating in watts (.5 watts) through the zener voltage. .5/13 = 38.5 mA. If 10 mA is necessary just to help keep the zener working, that leaves only an further 28.eight mA for your load at best.
To acquire R1 which must drop about 7 volts to protect the zener by restricting the current. To acquire R1 we must divide 7 volts by 38.5 mA. This arrives out to 180 ohms. The alternative would be to use a greater wattage zener.
As 1 adjusts the power provide from 0 to 13 volts the voltage measured by voltmeter 2 (Vm2) really should rise to 13 volts, Voltmeter one (Vm1) really should read zero, as well as the ammeter (Am1) really should read near zero.
Because the power provide reaches about 13 volts, the ammeter really should leap to 10 mA and as we increase the input voltage the voltage studying at Vm2 is pretty continuous, whilst the voltage studying on Vm1 grows. At twenty volts Am1 really should read about 38 mA, Vm2 13 volts, Vm1 about 7 volts.
This has a primary impedance of 1K along with a secondary impedance of eight Ohms. Employed in reverse the unloaded AC voltage is about 120 volts AC. This is rectified through the 1N4004 (or minimal equivalent, greater is Okay, including 1N4007) diode and smoothed (filtered) through the 2.2uF capacitor which Must be rated at one hundred fifty VDC. The Zener under test is measured using a multimeter set to DC volts as proven. The load current switch allows the Zener to be tested at one or 2 mA DC, the rectified DC load. Having said that, a great Zener really should preserve the studying on the volt meter.
ammeter, drop, Izt, mw max, power dissipation, secondary impedance, test, variable dc, vm1, volt