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Keantoken's CFP cap multiplier
Keantoken's CFP cap multiplier
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Old 5th July 2013, 10:52 PM   #421
Krisfr is offline Krisfr  United States
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Old 5th July 2013, 11:08 PM   #422
keantoken is offline keantoken  United States
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What current draw?
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Old 5th July 2013, 11:13 PM   #423
Krisfr is offline Krisfr  United States
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I am guessing about 100ma each rail, just front-end and the VAS, maybe safer to say 200 or 250, I am making it a part of a LTSpice sim. I have not got very far as I am working on the overall topology.

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Old 5th July 2013, 11:33 PM   #424
keantoken is offline keantoken  United States
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When I came up with the Kmultiplier I didn't imagine one would try to use it on a tube amp or something with really high rails. This makes it necessary to change some things. Anyone who doesn't want to consult with me on a Kmultiplier for over 50V use should use this schematic - with an input lytic of course.

How much voltage drop is acceptable? This version should work for up to 350V, and have more PSRR owing to the input RC.

Keantoken's CFP cap multiplier

Post 236

If you don't like the input RC, I have some other versions that will work but are not tested.
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Old 5th July 2013, 11:42 PM   #425
keantoken is offline keantoken  United States
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So, you need a bulky version. 100mA at 90V is 10W! So it seems you're running the drivers off the frontend rails.

You definitely need C5171/A1930 outputs, and an input RC is not acceptable. If your frontend capacitance is not humongous, as I've had to account for in the past, then a 3rd transistor may not be necessary.
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Old 7th July 2013, 08:43 PM   #426
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Hi Keantoken,
You are the perfectionist. I look forward to reading your power amp thread.
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Old 20th July 2013, 01:26 PM   #427
triode_al is offline triode_al  Netherlands
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I have built a K-multiplier for use as a pre-buffer for a Salas CCS/shunt regulator.
The output CCS is designed for 1 amp and it works fine.
I still saw some diode bumps (less than half a mV) on the output so I decided I needed a pre-reg. I inserted the K-multiplier on the negative rail.
Inserting the CFP multiplier, the current drops to 100 milliamps.
- I also see the voltage across the multiplier is arbitrarily 6-7 volts (depends if I use the CCS or a resistor). I did omit the LED by the way.
  • Is this an area (high voltage) where I should not use this circuit? [I remember having read something like that]
  • Is it true that there is a current limiting inherent in the circuit? What is the use then of a CCS?
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Old 20th July 2013, 03:26 PM   #428
triode_al is offline triode_al  Netherlands
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I have loaded the circuit with a 100 ohms resistor; input 14 V.
I installed the LED (I had omitted it because my cap is just 10 uF)
When I turn the power on, the LED lights, and dims somewhat but not totally.

I guess I got it: I use a TIP29C [Hfe <75] /a NPN HF transistor [about 100]; the combo is not very strong then. It is struggling to get current.

will have to look for a better combo in my box of available components then
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Old 21st July 2013, 01:31 AM   #429
keantoken is offline keantoken  United States
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I cannot guess what voltages and currents you are trying to run it at. If you look at the webpage in my signature you'll see that the max current for the C5171/A1930 version is 500mA or so. It may work up to 2A but probably not as well.

Here is a version designed for high voltage:

Keantoken's CFP cap multiplier

What is the CCS current? How much capacitance at the output of the multiplier?
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Old 21st July 2013, 08:57 PM   #430
triode_al is offline triode_al  Netherlands
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Quote:
Originally Posted by keantoken View Post
I cannot guess what voltages and currents you are trying to run it at. If you look at the webpage in my signature you'll see that the max current for the C5171/A1930 version is 500mA or so. It may work up to 2A but probably not as well.

What is the CCS current? How much capacitance at the output of the multiplier?
The purpose is for a shunt running at 0,8 to 1 amp. That is a lot for the DFP I understand. It is for 5 Volts out; input is 11-12 volts and raw input RMS is less than a volt; the CCS/Salas are there to take it to 5 volt.
The intermediate capacitances are not great; but I tested at 10.000 uF.

Why was the salas not enough?
In the Salas shunt output I saw residual glitches on my scope of less than a mV, but they were visible in the noise as a fast rising edge; this prompted me to add a capacity multiplier.
A normal one (with darlington) on the positive line worked well and reduced it to almost invisible;
so I decided to test the Kmultiplier; to see if that was better - and I put this kmultiplier on the earth line.

My analysis:
Very probably I got the problem because of using non-stock parts: I used diodes salvaged from boards; and these have a higher conduction point of almost 0,7 V; and I used TIP29C/BFX37. The BFX is exotic, I agree (but I have them) and looking at the specs it is a low level low noise transistor and I should replace it. The TIP has an Hfe of about 60; too low too probably (but it can cope with the 1A current for sure).

I'll test the base (diode) current.
albert
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