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-   -   Juma's Easy-Peasy Capacitance Multiplier (https://www.diyaudio.com/forums/power-supplies/297921-jumas-easy-peasy-capacitance-multiplier.html)

prasi 19th October 2018 01:02 AM

Quote:

Originally Posted by thimios (https://www.diyaudio.com/forums/power-supplies/297921-jumas-easy-peasy-capacitance-multiplier-post5576384.html#post5576384)
Red boards that i received Today are excellent!
Thanks Prasi!;)

thanks for confirming. those are different designs however.

pinnocchio 21st October 2018 04:23 PM

Hi Prasi,

Do you thing you could add the rectifier section of Project16/Prasi CRC PSU to this cap MX? I much prefer discrete diodes than square bridges.

All the best!
Do

prasi 21st October 2018 05:58 PM

Hello Pinnocchio, A design of diode section just like crc supply with SK104/129 heatsinks, etc would require a complete rework of the layout and would make the length > 100mm.

jwjarch 21st October 2018 06:17 PM

My boards have almost finished production from JLCPCB. Thanks for the gerbers Prasi! There was some discussion in another thread about slowing the ramp up of the CapMx via a revision to the RC time constant. Is there a simple way to accomplish this changing a few values? It would be a huge benefit to my ALPHA 20W build.

Project16 21st October 2018 06:34 PM

Hello all

Maybe a pcb with only the recovery part (to220 diodes, heatsinks and connectors) could come into being, so the choice with this pcb or bridge rectifiers standard would be possible.

pinnocchio 21st October 2018 07:26 PM

Quote:

Originally Posted by Project16 (https://www.diyaudio.com/forums/power-supplies/297921-jumas-easy-peasy-capacitance-multiplier-post5579118.html#post5579118)
Hello all

Maybe a pcb with only the recovery part (to220 diodes, heatsinks and connectors) could come into being, so the choice with this pcb or bridge rectifiers standard would be possible.

+1

xrk971 21st October 2018 08:26 PM

Hi Mark Johnson,
Thank you for the excellent cap mx design that you have given us. I really like how well it works. If we wanted it to have a very slow rising ramp output voltage, can we simply change R2 and R6 to adjust the R2/C3 R6/C7 RC time constant? On the Juma Easy Peasy cap mx, we have 10k and 220uF for a 0.7RC time constant of about 1.5s. This is nice for amps that have turn on thump problems as the slow rise eliminates this issue.

Can we simply change the 150R to 4k7 to really slow down the initial chargup - will it still allow the cap mx to work properly?

Thanks,
X

https://www.diyaudio.com/forums/atta...son_sch_r1-png

Mark Johnson 21st October 2018 10:04 PM

My "contribution" was merely to suggest three little tweaks

(a) Use a cascade of two emitter followers, so the base current drawn from the capacitor node is small, so you can use a bigger filter resistor ("R2" in post #607) and a smaller filter capacitor ("C4") yet get plenty of low frequency attenuation

(b) Connect a multiturn trimpot that lets you dial the dropout voltage (Vin - Vout) to be as large or as small as you like. It gives you a safety margin against propagating input ripple through the circuit onto the output, and you can set that safety margin as big or as small as you please.

(c) Connect the emitter resistor ("R4") of the upstream transistor ("T1") to ground, not to the output node. This reduces output impedance and improves performance with load current waveforms that are large dynamic range square waves, such as 5% to 99% to 5% to 99% to 5% etc

Other than that, the circuit belongs to whoever implements it. It's yours, it's not mine. Do with it as you like. Build it. Measure it. Simulate its behavior. If your simulation results show unexpected or weird behavior, rejoice! It's a learning experience! Dig in and understand what's going on and why things happen the way the simulator says they do. If you've made an honest and thorough effort, yet still can't understand your results, if you post your results along with your misgivings, diyAudio members could maybe offer their advice and analysis. Who knows, I might too.

prasi 23rd October 2018 09:23 AM

1 Attachment(s)
Quote:

Originally Posted by pinnocchio (https://www.diyaudio.com/forums/power-supplies/297921-jumas-easy-peasy-capacitance-multiplier-post5579146.html#post5579146)
+1

:D with new and improved features!

Vunce 23rd October 2018 09:31 AM

Nice Prasi!
This would be a nice board option to have on hand for a variety of projects.


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