| Electronics > Beginners |
| Transistor, i hate you! |
| << < (3/4) > >> |
| rstofer:
Here's a pretty decent discussion: https://northcoastsynthesis.com/news/exponential-converters-and-how-they-work/ |
| phiza:
--- Quote from: edavid on October 11, 2019, 07:52:22 pm --- nostalgia circuits --- End quote --- You got it right :-+ Well i can actually use an anti-log amplifier or any ic with an exp converter but i think that it's possible do it with only one bjt. (or I have to understand why it is not possible, careless of temperature) |
| ratatax:
I also quit my job to do something crazy, I think it's totally worth if you focus on your goals and if you can find a new job easily in case it goes wrong. You'll learn so many things, it's unvaluable. Just create some product that solves a specific problem better than someone else does, and you may (*MAY*) succeed |
| phiza:
--- Quote from: rstofer on October 11, 2019, 03:28:11 pm ---It would be interesting to plot Vbe vs Ic. I assume Beta was a given in your circuits but I don't know that. If it wasn't a constant, plot it! In fact, duplicate as many of the datasheet graphs as possible. --- End quote --- So I take your advice and plot the "familiar" graph of Vbe vs Ic then i change the scale from lin to log and it's interesting notice how the "exp conversion" change, careless of Rc. Between 510 mV and 646mV Ic doubles every 27mV pretty well, after seems to be a bit slower. But why 27mV? I set the simulation temperature to 20°C... I think it's the 2N3904 model parameters on multisim, I'll try to check it. Thanks everyone :) |
| rstofer:
--- Quote from: phiza on October 12, 2019, 02:03:12 pm --- --- Quote from: rstofer on October 11, 2019, 03:28:11 pm ---It would be interesting to plot Vbe vs Ic. I assume Beta was a given in your circuits but I don't know that. If it wasn't a constant, plot it! In fact, duplicate as many of the datasheet graphs as possible. --- End quote --- So I take your advice and plot the "familiar" graph of Vbe vs Ic then i change the scale from lin to log and it's interesting notice how the "exp conversion" change, careless of Rc. Between 510 mV and 646mV Ic doubles every 27mV pretty well, after seems to be a bit slower. But why 27mV? I set the simulation temperature to 20°C... I think it's the 2N3904 model parameters on multisim, I'll try to check it. --- End quote --- The article I linked above shows the doubling every 18 mV. Different devices? Clearly different models. Those graphs are very interesting. I didn't expect such a straight line in the log graph. |
| Navigation |
| Message Index |
| Next page |
| Previous page |