Timeline for Analyzing a constant current source
Current License: CC BY-SA 4.0
13 events
| when toggle format | what | by | license | comment | |
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| Oct 28, 2018 at 11:52 | history | edited | bobthechemist | CC BY-SA 4.0 |
Added reference to art of electronics so I know where to go when I forget the answer to this question.
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| Oct 21, 2018 at 9:00 | history | tweeted | twitter.com/StackElectronix/status/1053933941839798274 | ||
| Oct 21, 2018 at 1:50 | vote | accept | bobthechemist | ||
| Oct 20, 2018 at 11:38 | comment | added | andre314 | It's a kind of voltage overflow pipe. So if one wants to know if the overflow pipe is active, he sees what would be the voltage without the pipe and sees if it is above the threshold. | |
| Oct 20, 2018 at 11:25 | comment | added | andre314 | Here is the way to think a zener diode : If the voltage applied to the zener is above the threshold (5.1V), then the zener sinks so much current that the voltage drop to 5.1V (due to the external circuitery), otherwise, the zener is a open-circuit (otherwise it is burned, but in that case it is not called a zener anymore) | |
| Oct 20, 2018 at 0:40 | comment | added | sstobbe | A TL431 current source is a simple inexpensive alternate to play with as well. electronics.stackexchange.com/questions/107699/… | |
| Oct 19, 2018 at 23:09 | comment | added | bobthechemist | @andre Thanks for that clarification (this is my first exposure to zener diodes and their use). In the original design, the voltage source is 25 V, so I understand why it was necessary. | |
| Oct 19, 2018 at 23:08 | comment | added | bobthechemist | @ElliotAlderson Thank you for the comment; rp1/rp2 are actually part of a 1K potentiometer and I was using two different schematics (rp1 + rp2 = rp). | |
| Oct 19, 2018 at 22:34 | comment | added | andre314 | If the voltage of the zener were below 3.6 Volts, the zener would be usefull : it would make the generated current independent of Vbat. (of Conversely if Vbat were largely more than 9 Volts, the current would become independent of Vbat. Maybe the zener is a protection against overcurrent if Vbat is much larger than 9 Volts) ) | |
| Oct 19, 2018 at 21:26 | answer | added | andre314 | timeline score: 1 | |
| Oct 19, 2018 at 20:24 | comment | added | andre314 | The Zener is indeed useless, because VBat (rp1 + rp2)/(rp1 + rp2+ rs) = 3.6 Volts and the 1N4733A is a 5.1 Volts zener diode. | |
| Oct 19, 2018 at 19:59 | comment | added | Elliot Alderson | You need to indicate not just the location of a current but also its direction. Likewise, your equations have a voltage marked simply "v" and a resistor value of "rp" that are not shown on the schematic. | |
| Oct 19, 2018 at 19:54 | history | asked | bobthechemist | CC BY-SA 4.0 |