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)?
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)?
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
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
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,
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,
you are partial wrong
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 said: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.
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
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
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
PedroPO said: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
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
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
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