Activity for Circuit fantasist
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Comment | Post #279580 |
@Michaël Bensimhoun, Let's stop here. We exchanged interesting thoughts that give us food for thought. I am happy with that. Thanks for the comments. (more) |
— | almost 4 years ago |
| Comment | Post #279580 |
The problem of such a "BJT constant-current diode" is that it needs another (base) input voltage in addition to the voltage drop across the emitter resistor. The emitter voltage is subtracted from the base voltage and the positive difference (in the case of an NPN transistor) is applied as a bias vol... (more) |
— | almost 4 years ago |
| Comment | Post #279580 |
Regarding the RD circuit supplied by the collector voltage, I mean that when the load resistance varies, the transistor (no matter how "muscular" it is) will change its collector-emitter voltage VCE to compensate the load resistance variations... and this voltage supplies the Zener diode through a re... (more) |
— | almost 4 years ago |
| Comment | Post #279580 |
Regarding the decoupling capacitor, I mean that it is always a bad idea to quickly charge a capacitor... But really, in this case it has a small capacitance and this is not such a problem. (more) |
— | almost 4 years ago |
| Edit | Post #279592 |
Post edited: Specifying |
— | almost 4 years ago |
| Edit | Post #279592 |
Post edited: Added JFET constant-current source |
— | almost 4 years ago |
| Comment | Post #279580 |
Regarding the first (genuine) circuit diagram: The voltage drop across the resistor depends on the base and load current... and accordingly, on the magnitude of the ripples. So, I suppose, there is some kind of a self regulation of the voltage across the capacitor to the ripples. (more) |
— | almost 4 years ago |
| Comment | Post #279580 |
Regarding "the simplest possible activated current source, and hence, also, current limiter": It can be considered as a dual BJT version of the JFET "current diode" with a resistor in the source. However, here there is a need for an external reference voltage obtained by a Zener diode and a resistor... (more) |
— | almost 4 years ago |
| Comment | Post #279580 |
Regarding the trick with the Zener diode in parallel to the resistor: If the capacitor has not so small capacitance, it can be decoupled in the first moment by a diode connected between the capacitor and base (with the cathode to base); the Zener diode should be connected after the diode, to the base... (more) |
— | almost 4 years ago |
| Comment | Post #279580 |
I am trying to recall my comment accidentally deleted during the update: "Perfectly written paper with a lot of philosophy and various implementations. I guess it will also be of interest to you [What does this transistor circuit do?](https://electronics.stackexchange.com/questions/532326/what-does-t... (more) |
— | almost 4 years ago |
| Edit | Post #279592 |
Post edited: Minor edit |
— | almost 4 years ago |
| Edit | Post #279592 |
Post edited: Minor edit |
— | almost 4 years ago |
| Edit | Post #279592 |
Post edited: Minor edit |
— | almost 4 years ago |
| Edit | Post #279592 |
Post edited: Rewording |
— | almost 4 years ago |
| Edit | Post #279592 |
Post edited: Minor edit |
— | almost 4 years ago |
| Edit | Post #279592 |
Post edited: Making the transition smooth |
— | almost 4 years ago |
| Edit | Post #279592 |
Post edited: Minor edit |
— | almost 4 years ago |
| Edit | Post #279592 |
Post edited: Minor edit |
— | almost 4 years ago |
| Answer | — |
A: What is the difference between differential amplifier and differentiator? Both differential amplifier and differentiator react to a voltage difference. But in the differential amplifier, the difference is between two voltages applied to the amp inputs at the same time while in the differentiator, the difference is between two voltage values at adjacent moments of time. ... (more) |
— | almost 4 years ago |
| Article | — |
How to create current sources Background Constant current sources (simply, current sources) are useful and necessary devices. They are widely used to drive LEDs, charge capacitors and batteries, bias differential amplifiers, etc. The only problem is that... there are no such devices in nature; almost all of sources are (cons... (more) |
— | almost 4 years ago |
| Comment | Post #279527 |
Perfectly written article with a lot of philosophy and specific implementations... I would add also an interesting link to [What does this transistor circuit do?](https://electronics.stackexchange.com/questions/532326/what-does-this-transistor-circuit-do/)
(more) |
— | almost 4 years ago |
| Edit | Post #279016 |
Post edited: Clarifying |
— | almost 4 years ago |
| Edit | Post #279016 |
Post edited: Refining the text |
— | almost 4 years ago |
| Edit | Post #279016 |
Post edited: Replaced pictures |
— | almost 4 years ago |
| Comment | Post #279431 |
I should make a "little" correction to one of my comments above. Connecting a voltmeter in parallel to the diode will not introduce an error because the voltage across it is produced by a voltage source. Rather this will be a problem in the case when the diode is driven by a current source (the dual ... (more) |
— | almost 4 years ago |
| Comment | Post #279431 |
@coquelicot, nice circuit diagram... Do you realize this is the well-known non-inverting configuration where TD is R1 and AM2 is R2? Or, this is the well-known "non-inverting current source" where TD is a "functional voltage-to-current converter" and AM2 is a "current-to-movement converter" (analog ... (more) |
— | almost 4 years ago |
| Comment | Post #279431 |
... Of course, the ammeter will be floating. So in this solution either the voltmeter or ammeter are floating... but still there is a solution in which both are grounded. (more) |
— | almost 4 years ago |
| Comment | Post #279431 |
Another suggestion - put the ammeter into the feedback loop (between the op-amp output and the common node where the inverting input and diode are connected). There are two benefits of this trick: first, the op-amp will raise its output voltage to compensate the ammeter resistance; second, both the d... (more) |
— | almost 4 years ago |
| Comment | Post #279431 |
A good answer to my comment above… and demonstration of creative thinking… but there is another problem. If "the voltage is measured at the terminals of the diode with the multimeter", and the voltmeter is not perfect, it will divert a part of the current through the diode… and an error will appear. ... (more) |
— | almost 4 years ago |
| Comment | Post #279431 |
Simple and clear explanation... Now only the milliammeter resistance can create a problem. If only we can hide it somehow... (more) |
— | almost 4 years ago |
| Comment | Post #279413 |
Attractive experiment... If the load line could be shown... (more) |
— | about 4 years ago |
| Edit | Post #279016 |
Post edited: Minor edit |
— | about 4 years ago |
| Edit | Post #279016 |
Post edited: Refining |
— | about 4 years ago |
| Edit | Post #279016 |
Post edited: How to make a wide dead zone |
— | about 4 years ago |
| Edit | Post #279016 |
Post edited: About the narrow "dead zone" |
— | about 4 years ago |
| Edit | Post #279016 |
Post edited: Rearranging |
— | about 4 years ago |
| Edit | Post #279016 |
Post edited: Minor edit |
— | about 4 years ago |
| Edit | Post #279016 |
Post edited: Minor edit |
— | about 4 years ago |
| Edit | Post #279016 |
Post edited: Adding the TonyStewart's suggestion |
— | about 4 years ago |
| Comment | Post #279016 |
Ooooo ... now I just saw the simulation. Really very attractive and beautiful ... Thanks for the effort ... maybe it will help me to see something new in the solution. I like your idea to show two simultaneously acting versions - with and without bias. This shows the effect of bias. Do you agree wit... (more) |
— | about 4 years ago |
| Comment | Post #279016 |
@TonyStewart, Yes... but these wonders of today are only means that cannot replace the need for thinking. Because it is very unfortunate and comical to master them perfectly but not to understand what the ideas behind circuits are... and this is a ubiquitous phenomenon today. And it leads to this ... (more) |
— | about 4 years ago |
| Edit | Post #279016 |
Post edited: Minor edit |
— | about 4 years ago |
| Comment | Post #279016 |
Regarding your second comment, my goal is to show how the inventor thinks when a new idea conceives in his/her mind. This initial stage of the circuit development is the most obscure and least considered. For this purpose, I use a specific circuit in which there is some trick and therefore it was rec... (more) |
— | about 4 years ago |
| Comment | Post #279016 |
@TonyStewart, Thanks for the advice. Indeed, handmade drawings are not the usual technique today. I use them because they give me more freedom in exposing my ideas. In the 90s, I was using Corel Draw and in the 00s, Macromedia Flash animator. Then I started drawing schematics on a white board and wh... (more) |
— | about 4 years ago |
| Comment | Post #279030 |
@LvW, I am trying to explain your simulation results through my graphics... but there is something that bothers me. According to my graphs, such good linearity could only be obtained if the resistor would be dynamic ("current sink") because its curve then would be horizontal. How can you explain this... (more) |
— | about 4 years ago |
| Edit | Post #279050 |
Post edited: More about the virtual elements |
— | about 4 years ago |
| Edit | Post #279050 |
Post edited: Added another viewpoint at the "trans ekement" |
— | about 4 years ago |
| Edit | Post #279050 |
Post edited: Minor edit |
— | about 4 years ago |
| Edit | Post #279050 |
Post edited: Minor edit |
— | about 4 years ago |
| Edit | Post #279050 |
Post edited: About the reversed transistor transfer curve |
— | about 4 years ago |