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Keantoken's CFP cap multiplier
Keantoken's CFP cap multiplier
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Old 23rd May 2018, 02:24 PM   #1131
sianturi is offline sianturi  Indonesia
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Originally Posted by sianturi View Post
Hello Keantoken,

2SA1930/2SC5171 have been discontinued. Mouser doesn't stock them anymore

OTOH, the discontinuation notice from Toshiba states that the replacement for these are TTA004B/TTC004B, respectively. Can we use this?
It works! TTA004B & TTC004B. OTOH, i don't know how to measure the ripple with my oscilloscope....
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Old 23rd May 2018, 03:48 PM   #1132
RCruz is offline RCruz  Switzerland
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Keantoken's CFP cap multiplier
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Originally Posted by sianturi View Post
It works! TTA004B & TTC004B. OTOH, i don't know how to measure the ripple with my oscilloscope....
Good
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Old 24th May 2018, 12:12 AM   #1133
sianturi is offline sianturi  Indonesia
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K-Multiplier + Salas Shunt Regulator V1.2R

I finally managed to measure peak-to-peak and Vrms ripple, but not at the K-Multiplier output....
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Old 24th May 2018, 12:27 AM   #1134
keantoken is offline keantoken  United States
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Originally Posted by DNi View Post
Now, I know that several Members built this circuit with red LEDs and reported correct results, but I still don't know why it was different in my case.

Regards,
Braca
The version on my webpage uses 3 diodes instead of an LED, it is a bit old. Since the current boards use an LED, they seem to have a bit more voltage drop. You could replace the LED with 3 1N4148 in series, although the IR LED is apparently also a solution.
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Old 24th May 2018, 12:12 PM   #1135
DNi is online now DNi  Switzerland
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I'm about to build another two K-Multipliers, and have now a few more IR LEDs at my disposal, so the table from post #1130 will probably get an update.
However, in my experiments with the PCB offered by Keanu, only IR LEDs with shorter wavelengths (< 900nm) seem to have been capable of producing the target voltage drop of 1.8V across Q2.


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Braca
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Old 15th July 2018, 07:55 PM   #1136
DNi is online now DNi  Switzerland
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As promised, here are the voltage drop measurements for several LEDs in my K-Multiplier with BC334-40/Toshiba TTC004B (the circuit diagram from this thread, assembled on the Kean's PCB):
Click the image to open in full size.It seems that only the 850nm (wavelength) IR LED produces the desired voltage drop of 1.8V across the pass transistor Q2.
The results for the negative polarity K-Multiplier (BC327-40/Toshiba TTA004B) are virtually the same, so I'm not quoting them.

Regards,
Braca
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Old 16th June 2019, 10:29 PM   #1137
eris is offline eris  United States
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Default SMPS Attenuation

I was thinking of using a K-Multiplier to attenuate ripple in the output of a 27.6v SMPS (adjusted to 32v). The ripple is 200mv ptp and I'd run it first through a T filter (3rd order) and then the K-multiplier. After that I generate a +-15v virtual ground based on LM317/LM337 regulators.

The T filter I configured attenuates at 60db per decade as frequency rises above 328 Hz. What does the attenuation (input isolation?) curve look like for the k multiplier? From reading the specs it's somewhere around 66db for the positive version, but I don't know how frequency dependent that is. Not as good as a regulator, but it also doesn't consume power like a regulator.

Also max current looks to be 1.4A. I need just a little more than that -- about 1.55A @ 32v. Is there enough headroom to accommodate that? You say that it's linear up to 400ma. What's the behavior beyond that?

thx
eris
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Old 17th June 2019, 06:40 AM   #1138
keantoken is offline keantoken  United States
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You can use the D44H11G/D45H11G and BC550C from Onsemi with 50V capacitors. Since the higher current transistor is slower, the PSRR corner frequency is around 30KHz.
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Old 18th June 2019, 05:51 PM   #1139
eris is offline eris  United States
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Originally Posted by keantoken View Post
You can use the D44H11G/D45H11G and BC550C from Onsemi with 50V capacitors. Since the higher current transistor is slower, the PSRR corner frequency is around 30KHz.
Ok.

Just to clarify...

1) You're saying that the low-pass curve of the k-multiplier drops from 66db down to 3db at 30khz? What's the shape of that? Linear? Butterworth?

2) When using the higher current transistor, when does attenuation leave the linear region? With the default transistor it was about 400ma.

Thanks for all your work on this.
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Old 18th June 2019, 05:54 PM   #1140
keantoken is offline keantoken  United States
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It is just a 6db per octave slope.

I try to specify transistors so that PSRR will be high up to the maximum current, I don't rate it just based on power dissipation limits.
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