The simplistic Salas low voltage shunt regulator

[ikoflexer]

We're in uncharted territory here. I haven't finished my high current regulator, so you'll be the first if it works. Hang tight, I got a schematic coming. I'm doing some sims for sanity checks.

[Tham]

Good to hear .

[ikoflexer]

Tham, here it is. 3A idle current through shunt mosfet on 0A load. Go hunting for a huge heat sink. Maybe you need a fan too.

Rset_current will set the current through the shunt. Higher value, higher current. You can use a variable resistor there, start with about 100R and go up.

There is a new feature, R4 + C3. You can adjust the output impedance by changing R4. Higher value of R4 means lower impedance. At the moment it is set to be sub milliohm all across the frequency range of interest. If you want, you can play with it, bring it up to 6k8, 7k5, 8k2, 10k, 15k, 20k, 27k, 33k, etc. I doubt that it will stay stable when the impedance is a few micro ohms, as it is capable of a lot of gain, that loop.

C1 and C2 are the high frequency compensation caps. See what works in reality. No need to go too low on those. The values shown in the schematic give a nice flat output impedance well into the high frequency. If unstable, choose larger values.

And, finally, the 2sk170, 7.5mA Idss might be ideal. Those are the values I simulated. Especially the J1, J3, and J4.

Good luck, and please let us know how it works out.

Edit: forgot, make C6 = 1000uF. I only use 100uF in simulation because it takes too long with large caps in that position. The 1000uF cap will pretty deal better with the zener noise.

[Tham]

Iko, thanks! you are real quick. I will give it a go and report back. Time to go to the electronic vendors again ...

[Salas]

Is that the 10W chip that needs about 13V? If that is, I have mentioned I think that there is one running from 2008 on V1. We had it on 3A, driving Hemp 8 inch, 8 Ohm FRs, then we got it down to 2.5A, no compression. My friend's comment is that it is better than his 300B with such a reg. Its hot though, because T-Amps are asking for nothing when idle. So we have a cold amp and a hot reg. Life's irony.

[ikoflexer]

A CPU heatsink with a fan will work well, if you can find a quiet one. And I hope you plan to build one shunt per channel

I would first test it with a light bulb of appropriate size as load, or something like that.

[Tham]

Yes, it is a 10w cold running amp that I am trying to run with a hot regulator and hoping that it sounds better than a 300B as mentioned

[ikoflexer]

Originally posted by Salas
Is that the 10W chip that needs about 13V? If that is, I have mentioned I think that there is one running from 2008 on V1. We had it on 3A, driving Hemp 8 inch, 8 Ohm FRs, then we got it down to 2.5A, no compression. My friend's comment is that it is better than his 300B with such a reg. Its hot though, because T-Amps are asking for nothing when idle. So we have a cold amp and a hot reg. Life's irony.

http://www.kafka.elektroda.eu/pdf/tripath/TA2020.pdf

Sometimes I do shudder when I think how much current goes through the thing while it does nothing at all. But then I remember about filaments on tubes and don't feel that bad

Quite impressive that it sounds better than the 300B. Wow.

[Tham]

I had a coolermaster cpu heatsink complete with turbine fan if ever need to go to that extent. I am actually thinking of a sizeable heatsink that I can cannibalized from an unused av amp.

[Tham]

My T amp sounded very good with a simple linear reg built from a 7812 now. With a v1 or v2, it should be way better still.