Introducing the PowerReg

teddy_pardo · #1 27-09-07, 12:03 PM

Following the TeddyReg and as a results of many nights and weekends of experiments, here comes the PowerTeddyReg. It is based on the same concept but can deliver several amperes (depending on selected dropout and heat sink) and has much lower output impedance.

Here is the circuit

Components are

R1 = 3.4K
R2 = 150R
R3 = 40-60K
R4 = not required
R5 = 40-60K
R6 = 100-250R

C1 = 0.1uF X7R Ceramic (optional)
C2 = 10-20uF Tantalum
C3 = 10-20uF Tantalum
C4 = 33uF Tantalum
C5 = 0.2-0.3uF X7R Ceramic
C6 = 10-20uF Tantalum/Oscon

T1 = SK117 GR
T2 = BC550C
T3 = D45H11
LR1 = LM317

Note that with a FET transistor and Sziklai-pair the dropout on the VBE is minimal (less than 1Volt) therefore the output voltage is mainly determined by the LM317.

This regulator can be used for power amplifiers and the effect it has on the gainclone is quite astonishing. I have used a pair of these regulators (positive and negative) per channel, powered by a single 120VA transformer and cheapo miniature 10.000uF capacitors. Results are jaw dropping, it's comparable if not superior to many high end power amps discussed in this forum including my own one.

A complete one-channel power amp including heat-sink, two regulators, and a trimmed GainClone PCB can fit in a 6x6x6 cm module. Isn't it cute?

My next project: a miniature active cross over using these modules. Stay tuned...

Enjoy, Teddy

yairf · #2 28-09-07, 12:02 AM

Teddy
You should trademark your "product" names, who knows...

MarkW · #3 28-09-07, 01:26 AM

Teddy

Interesting stuff and nicely done. How does the GC sound with this psu arrangement?

Mark

new naim boy · #4 28-09-07, 03:39 AM

Teddy: Would you recommend the PTR for the SB3?

Agent_Cooper79 · #5 30-09-07, 10:35 AM

Teddy, I am very impressed!

Couple of questios though;

Can the amp really still deliver the same power as with "real" PSU-caps? The reason I am asking this is the fact that the cap in the VBE looks like a bigger cap but can't really store the energy of the real cap.

What is the reason for omitting R4, is it because you have a FET at the base of the VBE?

Looks like fantastic work, thanks for making it available!

/Magnus

teddy_pardo · #6 30-09-07, 10:50 AM

Quote:

Originally Posted by new naim boy

Teddy: Would you recommend the PTR for the SB3?

Don't know. I would assume yes but no way to try it.

teddy_pardo · #7 30-09-07, 10:55 AM

Quote:

Originally Posted by Agent_Cooper79

Teddy, I am very impressed!

Couple of questios though;

Can the amp really still deliver the same power as with "real" PSU-caps? The reason I am asking this is the fact that the cap in the VBE looks like a bigger cap but can't really store the energy of the real cap.

What is the reason for omitting R4, is it because you have a FET at the base of the VBE?

Looks like fantastic work, thanks for making it available!

/Magnus

Yes, it can easily deliver enough power to drive a 50W power amp, maybe even more. When fully driving the power amp, the ripple looks much better on the oscilloscope than any other large capacitor combination. It sounds much better too.

R4 is usually used to create some dropout on the VBE, in this case since the collector is connected to the rail, the LM317 takes care of the VBE dropout.

Baki · #8 01-10-07, 02:45 AM

Hi Teddy,
excellent work indeed.
I've been experimenting a lot and implemented more than 10 VBE based regs (alone, before and after linear regulator) in my cdp and integrated amp.
One question seems inevitable.
When to implement TeddyReg and when PowerReg?
For example, what is your recommendation regarding the regulation of cdp opamp output stage (low power consumption, but low output impedance could be beneficial...)?
Best,
Baki

teddy_pardo · #9 02-10-07, 12:50 PM

Use PowerReg only when you need power. The TeddyReg has better regulation as it has two levels of regulation the LM317, followed by the VBE. On the PowerReg the power transistor is connected directly to the raw rail. It's still very quiet, but probably not as much as the other.

PigletsDad · #10 03-10-07, 01:49 AM

Another point:

The PoweReg only has low impedance when you draw a lot of current from it; at low current drains the transistor impedances are quite high. A fair rule of thumb is that the output impedance will be 26Ohms divided by the output current in mA.

Puffin · #11 03-10-07, 04:32 AM

What would need to be altered to give an output voltage of 12vDC ?

Nuuk · #12 03-10-07, 05:53 AM

Quote:

What would need to be altered to give an output voltage of 12vDC ?

Set the LM317 to output 13 volts. That is done by selecting the correct resistors.

If you go to Decibel Dungeon and download the hi-fi caluclator, you will find it has a section to calculate the required resistor values.

In this case 200R/2k would give you around 13.75 after the LML317 and about one volt less than that after the power reg circuit. Or you could use a trimmer to get 212R/2K for 13 volts after the LM317.

Puffin · #13 03-10-07, 07:48 AM

nuuk. Thanks for that I had considered a trimmer or maybe a 7812 in place of the 317 ?

Pulse Studio · #14 03-10-07, 08:42 AM

Teddy wouldn't the reg be better served as a " K " series variable voltage affair?

maxlorenz · #15 01-11-07, 03:10 PM

Hi Teddy,
It's me again

I am buying the parts for PowerReg and TeddyReg.
Questions:
1) You run your chipamp around 28VDC, wright?
Could the LM317 in your configuration be settled to >35VDC?

2) I got dizzy trying to find JFETs

I found 2SK117-BL (BL instead of GR)
http://www.ampslab.com/PDF/2sk117.pdf
and 2SJ103-Y as P-channel JFET (audio amp instead of "low noise audio")
http://www.ampslab.com/PDF/2sj103.pdf

Are these OK?
They are $20USD per 20 units.

Thanks,
M