Timeline for Is this boost converter feedback technique a good idea?
Current License: CC BY-SA 4.0
16 events
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| Dec 30, 2022 at 18:00 | history | tweeted | twitter.com/StackElectronix/status/1608885681773748225 | ||
| Dec 28, 2022 at 4:09 | comment | added | Russell McMahon♦ | Something along these lines will work A driver can be a simple bjt pair. || I suggest turn on on positive drive may be better. A single npn emitter follower driver gives good turn on. || Adding a zener in the feedback path allows a smaller divide ratio. || Adding some positive hysteresis on gate turnoff squares things up. I can provide a suggested circuit including above if of interest. || I did a buck converter similar to this with thousands built. || MC34063 is crude old cheap and very very useful. Driving an external FET it can be cheap and effective. A design of mine ran to 200,000+. | |
| Dec 27, 2022 at 2:30 | answer | added | PStechPaul | timeline score: 1 | |
| Dec 27, 2022 at 1:32 | comment | added | PStechPaul | Why not just use an ADC on the Arduino for reading the feedback, and adjust duty cycle accordingly. But determine the maximum duty cycle and limit that to a "safe" level. Use a push-pull gate driver and logic level MOSFET. | |
| Dec 26, 2022 at 23:52 | answer | added | Kuba hasn't forgotten Monica | timeline score: 2 | |
| Dec 26, 2022 at 8:37 | comment | added | greybeard |
(No.) Shouldn't the converter be fed from 24 V rather than 12 V? If the 24 V are stabilised, just using a 25:3 on/off PWM should go a long way without any feedback. (\$t_f \gt t_r\$ counter-acting losses, decent smoothing more important than accuracy.) Consider distancing the tube pre-amp from any switch mode equipment. (12 V to 200 V would be pushing transformerless converters. Then again, at just 15mA…)
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| Dec 26, 2022 at 8:03 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Feb 1, 2022 at 1:06 | answer | added | Autistic | timeline score: 0 | |
| Jan 31, 2022 at 19:41 | history | edited | JRE | CC BY-SA 4.0 |
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| Jan 31, 2022 at 18:36 | comment | added | G Frank | saying that, 220ohm would be well to low to shunt, and would cost to much current... maybe not. | |
| Jan 31, 2022 at 18:22 | comment | added | G Frank | I would start by removing the bjt on the left and the 2.2k resistor. then adding a resistor (maybe 220ohm) in series with the mosfets gate. efficiency isn't to much of a concern. as long as it's half reasonable. highest priority is keeping the output as ripple free as possible and any noise kept out of the audio band. | |
| Jan 31, 2022 at 18:16 | comment | added | Klas-Kenny | My point is that the feedback works by not allowing enough gate voltage to fully open the MOSFET. What you have created is basically some hybrid switching/linear regulator. How would you connect the feedback if using a proper gate driver? | |
| Jan 31, 2022 at 18:16 | comment | added | Wouter van Ooijen | I think Klas-Kenny is worried that when the feedback transistors starts conducting, the mosfet will be switched less efficiently (be operated in its linear region instead of in saturation) | |
| Jan 31, 2022 at 18:07 | comment | added | G Frank | 5.4mA peak. I kept the collector resistor low, as to have plenty of current to drive the mosfets gate capacitance. I would probably go with a driver IC for the final design. | |
| Jan 31, 2022 at 18:02 | comment | added | Klas-Kenny | How much power is dissipated in the switching transistor with this feedback model? I'd expect it to be pretty inefficient. | |
| Jan 31, 2022 at 17:51 | history | asked | G Frank | CC BY-SA 4.0 |