son of Zen-lite

[PedroPO]

After a few unsucessfull tries, I finally found a lamp combination that might work. 4x12v50w halogen lamps.

the resistance of that combination at 24.1 V is 8.033ohm at 3A.

I guess it might work. i'll try it tonight.

My only doubts are the following:

- can I substitute the positive( or negative) rail 8ohm resistors only, or should I change all the 8ohm resistors?

- the value of the resistors in both rails must be the same (symetrical)?

 

[Nelson Pass]

If they look like 8 ohms, you can put them
in anywhere as you like.

 

[PedroPO]

thanks,

if they have 8 ohm i guess its ok, but if they have a litlew more or less?

should I replace all the 8ohm resistors?

or can the positive rail resistors be diferent of the negative ones?

 

[Variac]

As Nelson mentions in his Zen lite site, there is some concern that halogen bulb do not last very long run at lower voltages.

As I understand(?) it, tungsten is being continuously blasted off the filiment in any bulb -that is why they fail. In quartz halogen bulbs there is apparently a cycle set up that deposits the metal vapor back onto the filiment instead of the glass.

I suspect that one of the reasons the Q-H bulbs are whiter light is that they can be run hotter without burning away the filiment
The claim is that at lower temps the cycle doesn't work.

I used a 300 watt Q-H bulb pointed against the wall to light my living room for a long time and the bulbs lasted for years, even though they were dimmed often. BUT they were always run up to full brightness often too

I think you will have no problem, the dim filiment probably doesn't spew off as much tungsten.

Please keep us informed how this works out, the amount of power you are running through them, and the brightness- do they glow or are they pretty bright?

I wanna make an Bulbous X Son o Zen

 

[GRollins]

I'm still waiting for some clever young lad or lass to hit upon the idea of using the lights from the amp circuit as illumination for their DIY video projector, thus killing two birds with one stone...

Grey

 

[df]

Zen light

I've build a Zen-lite with 3 x 35W/12V per channel and 40 V rails. It works perfectly. I had 2,6 A running and 9Volts per bulb so the hologen cycle works. With six 35W halogens it was to bright for me, so I'm rebuilding it to Var2.

Daniel

 

[Nelson Pass]

The 8 ohm values are not at all critical as long as they
are somewhat matched.

I am informed that Halogens at these low voltages will
mirror the reliability of standard incandescents.

 

[PedroPO]

thanks,

define somewhat: 0,1V? 1V? 10V?

I really don't know...

 

[Nelson Pass]

I mean matched enough that the amplifier does
not show serious DC across the load, which in
my book is 100 mV.

 

[gromanswe]

Load dependent

I mean matched enough that the amplifier does
not show serious DC across the load, which in
my book is 100 mV.

Be careful with HEADphone
they can not take so much current
I have Burned someones
Using them as My StetoScope
I like a doctor, ya 'now

Nice to see you Nelson
I have waited
and I am not the only

i know you soon

gro

 

[PedroPO]

Nelson Pass:
do you mean that if i put for example 2x8ohm resistor on the negative rails and 2x10ohm lamp on the positive rails I might get DC in the output?

I belive from my modest knowledge that dc offset is the result of assimetries in both sides of the diferencial pair, like mosfet diferences or resistor diferences (am I wright?).

What I am talking about is a diference in resistence between R1=R2 and R3=R4 in your SOZ circuit.

Can it cause trouble? If not I'll put the lamps only on one rail.
But I'm not sure that I can match 8ohm like the resistors with the lamps.

Thanx,

 

[gromanswe]

you are partial wrong

I believe from my modest knowledge that dc offset is the result of assimetries in both sides of the diferencial pair, like mosfet diferences or resistor diferences (am I wright?).
What I am talking about is a diference in resistence between R1=R2 and R3=R4 in your SOZ circuit.
Can it cause trouble? If not I'll put the lamps only on one rail.
But I'm not sure that I can match 8ohm like the resistors with the
lamps. Thanx YOU

But
do you make your own caculating
when trim
your
power handling device?

Best so! We are after ALL DIY People
nicht war?

gro
MAN
form
SWEden

 

[PedroPO]

gromanswe:

well I dont calculate anything more dificult then V=RI because I don't know much more (university physics).

I also don't know what you mean with "trim your power handling device", sorry

What do you mean with parcially wrong?

pls help me on this, Can I switch just R1 and R2 even if the resistence doesn't match with R3 and R4 (wich in fact are in paralell so it results in 4ohm resistor, 100W

 

[gromanswe]

gromanswe:

well I dont calculate anything more dificult then V=RI because I don't know much more (university physics).

I also don't know what you mean with "trim your power handling device", sorry

What do you mean with parcially wrong?

pls help me on this, Can I switch just R1 and R2 even if the resistence doesn't match with R3 and R4 (wich in fact are in paralell so it results in 4ohm resistor, 100W

you are WISE
I never usually calculate anything
but with
OHMS LAW

many others not being so wise
come Far FAR from goal:
ENJOY gro's MUSIC groman music groman songs

 

[gromanswe]

One of My songs

many others not being so wise
come Far FAR from goal:
ENJOY gro's MUSIC groman music groman songs

Try my homepage with
"gratias a la vida!" MUSIC

press down here "profile"
there is my home page

DOWNLOAD
in my dreams - 1:55 - 0.8 MegaByte

and play with WINAMP (mp3)
sa lo TAAA
Eusebio - people

 

[PedroPO]

Did it.

I replaced both R3 and R4 (8ohm resistors) with 3x12V50W halogen lamps

the voltage drop at R3 before the lamps was 8.71V. With the lamps is now 8.72V 1.8A so the power dissipation is about 15.7W.

I tried it also with 4 lamps and the voltage drop was about 8.9V. the DC offset at the output did not change with the lamps.

It seems to work just fine

I wonder what happens if a lamp blows?
do I blow the fet? or the speaker?

I'll post later a temperature test with and without the lamps and some pics

 

[gromanswe]

1. Did it.
2. It seems to work just fine

3. I'll post later a temperature test with and without the lamps and some pics

I am glad for you, PEDRO
- Happy people are best -

groman
Swedish
fotball
likes

 

[cp642]

Pedro,
As I can recall, Nelson did mention...if a lamp blows, the amp turns off as the bulb is in series with the supply....now the bulb sound like a fuse..

 

[Nelson Pass]

If you use bulbs in parallel, the amp keeps going,
but with less output current available.

 

[PedroPO]

I have 3 bulbs in series. If one fails no current will flow, but just on the negative rail. can it cause some kind of death in the mosfet and speaker?