Silicon Diode is the most common use but for some circuit it need a schottky diode . Schottky diode has low voltage drop and fast recovery time so it can operate with high frequency application. We know voltage drop across Silicon Diode is 0.5-0.8V and 0.1V - 0.45V for schottky diode. I have sample of both 1N5402 standard general purpose Silicon Diode , 1N5820 for schottky diode. I will measure it and present the result on this article.
1. Silicon Diode Checking.
The voltage drop across a Silicon Diode is 0.5-0.8V and on photo = 0.528V
Forward bias of 1N5402 Silicon Diode.
For analog multimeter you can use LV scale to check the voltage drop across Silicon Diode as show below. Set knob to Rx1 range and make zero ohm adjustment to get the accuracy value before using LV scale. At LV scale there is 0 , 1 , 2 , 3 scale and this case from photo below the measured value is around 0.7V
Use LV scale to check voltage drop across 1N5402 Silicon Diode. Use Rx1 range and read value from LV scale. On this example is around 0.7V
The Silicon Diode has no leakage current , on photo use analog multimeter Rx1 range Function as 3VDC 150mA current source and use digital multimeter to measure leak current , the digital multimeter show no leadkage current when applying reverse bias then reverse the test leads , connect diode as forward bias there is some current flow 103.9mA.
No current flow ( Reverse Bias of Silicon Diode )
Current flow ( Forward Bias of Silicon Diode )
2. Schottky diode Checking.
Schottky diode has 0.1V - 0.45V drop across it. This case on photo below the measured value is 0.123V ( part number 1N5820 Schottky diode ).
Example of voltage drop across Schottky diode.
When applying reverse bias to Schottky diode there is some leakage current , this case we get measured current value 31.7uA ( part number 1N5820 ). I use current source from Rx1 = 150mA 3VDC ( test function from analog multimeter).
3. Unknown type of diode
Part number MUR820 (U820) on datasheet give information as Ultrafast Diode.
I test and get measured value as 0.426V voltage drop across ( when applying forward bias ) and no leakage current when applying reverse bias so I think it should be Silicon Diode type.
There is not leakage current when applying reverse bias to MUR820. There may be much small amount as nA so standard Digital multimeter can not measure it.
