DIY Audio Projects Forum

pinout of LM317?
isn't it the same of it from all manufacturers?

looking at the LM317 directly... at the label while pins facing down...
from left... pin 1, adj; pin 2, out, pin 3 in? and pin 3 connected to source of IRF510, isn't it so? which is pin 3 of the MOSFET?

I have found the problem and fixed it. it was a mistake, silly one... I messed up the pinout of the tube. I read the pins when they are placed in socket instead of from the bottom of the tube...

It is now working fine. but i have questions, why there is a loud 'thump' when I turn the amp on? I am using two 6V batteries as the power source. When it is on, I measured the voltage and it is 10.5-11v, why so?

Is there anyway to make it give out 12V?

Heh - yup, the old Tube diagrams are pictured 'from the bottom'... good one to remember.

The *thunk* - probably because the FET and LM317 are immediately brought to power-up, but the tube takes maybe a good 30 seconds or more to warm up - so for a brief while the FET has no 'control' on it's gate - actually, it's pulled UP to 12VDC, so all is 'akimbo' until the Tube warms up.

The scope of the project didn't originally include one, but I inserted a few extra components to control a DPDT relay which energizes after about a 45 second delay on power up. Stole it from the Millet Max

http://www.diyforums.org/MAX/MAXe12.php

(AKA Ti Kan's e12 delay relay)

If you're keeping the simplicity of the project, it should be fine as it is; perhaps delay plugging in phones for 30 seconds or so if the sound is objectionable.

The current draw from all sources (Tube Filament is the big hog, but also the LM317's and the FETs), is about 400 milliamps - almost half an amp. I've used a 12V Gel battery - similar to what's found in UPS PC Backups. You'll still need to charge it after using it each time. If you're using 6V dry cells (Lantern batteries) these aren't rechargeable, and may not have the current carrying ability of a much larger gel battery.

Mike Y
Dallas, Texas

guys i have somthing funny
an old ecc85 wit worn down filaments does also works great
(it clips faster but sound is clearer)

So, the 'thunk'... will it damage the headphones?

Yes, I am using lantern batteries, 2 of them... are you saying that it couldn't supply such current to the amp? I tested the tube heater before plugging in, it glows much brighter heated alone without the MOSFETs and the LM317.

Besides the batteries, what other sources of power can I use? Laptop adapter? Router adapter?

Oh, about the MOSFETs? The original project uses IRF510... but have anyone tested other MOSFETs? IRF610?

How other MOSFET differ in sound quality, bass, clarity etc?

>Thunk...
I suppose it could damage headphones; not sure, though.
I don't go for the over $200 headphones, so I'm not risking much when I use $38 Sennheiser's
or $50 Sony's.

>Batteries...
Depends on the voltage and how fresh the batteries are (if they're dry batteries). The tube
filament is rated at 12.3 volts, +/- 10%, so it'll work down to 11-ish volts.

From tube data:

http://www.duncanamps.com/tdsl/show.php?des=12AU7

... the heater alone pulls approximately 150 ma, so it's the FET/LM317's that are pulling most of the current. I've measured just over 400ma total.

> Power alternatives...
The article gives a specific 'scrapped' power block (I think from an old printer), which is *regulated*, and so doesn't induce any noise.

If you can find a 12 or 13 volt laptop supply, these are usually regulated. The Gel battery is going to be quietest, though. And you can put it on a charger after using it to maintain it's charge...

Mike Y

i use the irf 520
it works great
and it has more power to
i get it to pull 300W speakers

How does it differs compared to IRF510?

You used it to drive speakers?

How to know if it is a regulated supply?

Are computer power supplies ok for this?

About the gel battery and sealed lead acid battey, I am afraid with the charging...

My tube is glowing, there is sound but the glowing is just 4 red-Orange dots; 2 on top, 2 at the bottom. They are just glowing dots, and not bright enough to light up the other components even in a dark room.