Timeline for Current source for milliohm loads?
Current License: CC BY-SA 3.0
9 events
| when toggle format | what | by | license | comment | |
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| Dec 8, 2020 at 18:58 | comment | added | D.A.S. | Interesting choice of power transistors with low Vce(sat) implies Rce~ 1/16 Ohm with high hFE but is completely unnecessary with negative feedback reducing the driver impedance and the mag power is far too low with <1W | |
| Jul 15, 2014 at 8:39 | vote | accept | lrasinen | ||
| Jul 14, 2014 at 20:31 | comment | added | Spehro 'speff' Pefhany | R5 is not too small wrt the medium frequency output impedance of most op-amps (usually around 100 ohms) and prevents oscillation via C1/R6. If you make it much higher, then it won't allow enough current to get to the bases, much lower and it won't perform the desired function. | |
| Jul 14, 2014 at 20:08 | comment | added | lrasinen | Looks like I could pull that off. One more thing(TM): What's the rationale for the R5 value? | |
| Jul 14, 2014 at 20:05 | history | edited | Spehro 'speff' Pefhany | CC BY-SA 3.0 |
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| Jul 14, 2014 at 19:56 | comment | added | Spehro 'speff' Pefhany | See edit above. You could use higher voltage for the supplies, (like +/-5v) but the transistors will get hotter (10x the dissipation) and would require heatsinks. | |
| Jul 14, 2014 at 19:53 | history | edited | Spehro 'speff' Pefhany | CC BY-SA 3.0 |
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| Jul 14, 2014 at 19:27 | comment | added | lrasinen | Unfortunately I've always found the BJTs a bit mysterious, so could you please provide a bit more details about the transistor solution? (Should have taken up the opportunity to learn in the university, but I only needed to pass the basic electronics course and knowing the op-amp was sufficient...) | |
| Jul 14, 2014 at 18:09 | history | answered | Spehro 'speff' Pefhany | CC BY-SA 3.0 |