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Elvee 2nd November 2010 06:11 PM

The Voltage-Regulator-Chip Amp family welcomes a new member:
3 Attachment(s)
After the JLH, the Chtringlunator and the Voltage Regulator Chip Amp, here comes the Circlo, Half-Diamond Unity Gain Buffer, another "funny amplifier".

It operates in class A, and as usual, R2 can be halved with real LM317's.
The simulated and measured distortions are in perfect agreement.

As a bonus, the complementary regulators half diamond topology has a negligible in/out offset voltage.

ratza 3rd November 2010 07:53 AM

You're really bored, aren't you? :D

Elvee 4th November 2010 02:11 PM

Sorry, I made a small (but crucial) typo on the schematic: R4 is 4.7 ohm, not 47.

It changes nothing to the sim, but the actual circuit will oscillate like mad with 47R.

Atilla 9th November 2010 08:21 AM

Man, do you have any idea how many of those I've got? I'm already preparing to try them, cause I can literally use those regulators as a wallpaper, that's the amounts I keep around.

Your circuits are just too funny not to try :)

Elvee 9th November 2010 05:19 PM

You can easily parallel a number of them by inserting a small resistor (~0.1ohm) in each output terminal.
In the circuits where a resistor already exists (current sources, etc, ), you just have to duplicate the resistor+regulator the number of times required.

Will this lead to a 1KW voltage reg chip amp?
On a 0.2 ohm load then, unless you (or I) find a way of series-connecting them for increased voltage output.

The next project maybe.....

Zigis 10th November 2010 10:03 PM

Really fanny, i want to try too, one of this.

I have few questions:
Is it amp with gain or just buffer?
If there is gain, how much and how to calculate?
Max output power? (with 1 pair in output)
Can I power this amp with PS build on pair LM317/337 to max output?

The same questions about JLH amp, especially about gain.

Elvee 11th November 2010 07:50 AM

This one is just an accurate unity-gain buffer, and it operates in class A (you need sufficient heatsinks, but one good thing about voltage regulators, they will shut-down if the temperature rises too much. Heatsinks are therefore much less critical than for a traditional class A).

This one is also in class A, but it has gain, and is a complete amplifier:

The Chtringlunator is a unity gain output stage for headphones.

It could be preceded by the voltage amplifier of the Tringlinator to make a complete (and completely exotic) headphone amplifier.

This one is also a complete amplifier, operating in class B:
To alleviate the slew rate problem, R9 can be shorted to increase the quiescent current.
Further increase in the Iq could be obtained by using a lower voltage reference than the LT1009 or LM336: an adjustable 1.2V ref, wired for 2V for example.

The gain calculation is similar to a normal amplifier: for the Regulator-Chip Amplifier, it is 1+R6/R11, and for the JLH it is R7/R6.

The standard regulators limit the current to 1.5A^, that is ~1Arms. That's about 8W on 8R load.

You can off course use voltage regulators to power them:D

Elvee 12th November 2010 01:27 PM

The maximum output power attainable by pushing the total supply to 40V and using a number of parallel pairs in a BTL configuration is ~140W on a 4R load.

This requires 2 groups 6 pairs minimum, that is 24 devices. In practice, to deal with complex loads, etc, 8 pairs minimum would be preferable to reach 125W realistically.

A bit parts-intensive, but the resulting amplifier would be exceptionally robust.

Zigis 12th November 2010 03:23 PM


In real, material world soldering 24 devices is not too big problem, problem is enough large power supply (transformer)

I am thinking about simple JLH for the beginning. What purpose are for R2,R9 instead of one resistor and input, output grounds to ground?

Elvee 14th November 2010 08:52 AM


Originally Posted by Zigis (
What purpose are for R2,R9 instead of one resistor and input, output grounds to ground?

It is an attempt to balance the current swings of the two output devices:

The total value of R2 + R9 cannot go below approx. 1.6 ohm (1.25V/0.75A).
This imposes the effective transconductance of the lower device.
Balancing can then be made by correctly dimensioning R4 wrt. R3, but a relatively large R4 would be required, leading to a diminished negative voltage swing.
Splitting the resistance between R2 and R9 gives one more degree of freedom, and enables a symmetrical swing without the limitations.

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