sharpie7 / circuitjs1

Try this simulation of a 1N34. When inputting voltage from 0 to 500 mV, the current only reaches 1.363 micro amps:

But germanium diodes are typically said to have a rough threshold around 300 mV, and all datasheets and plots of 1N34 diodes I can find on the internet show the current should be well into the milli amp range by the time its voltage is 500 mV, for instance:

I looked at

circuitjs1/src/com/lushprojects/circuitjs1/client/DiodeModel.java

Line 90 in dd47cf4

addDefaultModel("1N34", new DiodeModel(200e-12, 84e-3, 2.19, 60, "germanium"));

but it seems to match what https://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/spice-models gives. Though there are some parameters left out from that...maybe they are necessary? Or maybe there is some other error simulating it in DiodeModel.java?

Thanks as always for such a great tool.

I don't notice any glaring issues with the two Shottkey diodes, which are also low-threshold diodes and match my limited understanding. But the 1N34 seems way off...maybe it should just be deleted from that menu if fixing its simulation is too hard.

Have you seen this:

https://forum.allaboutcircuits.com/threads/error-in-1n34-spice-model.48758/

I tried it with MacSpice and got exactly the same results. I guess the model is just bad. Deleting it from the menu seems like a good idea.


vin 1 0 0.5V

.MODEL D1N34 D(IS=200P RS=84M N=2.19 BV=60 IBV=15U
+ CJO=4.82P VJ=.75 M=.333 TT=144N)

DX 1 0 D1N34

.control
* dispose of any 'save' statements from previous runs
delete all
* perform a transient analysis
tran 0.01ms 10ms 0.0ms 0.2ms
plot i(vin)
.endc

Ahh. Yeah...just delete it for now.

1N34 (germanium diode) incorrectly simulated?