The Effects of Reflector Design and Lamp Orientation

[SmC252]

What about making our lights into lasers? Talk about focusing light! It really is not as hard as one would think, we made one back in science club when I was like 12 using a 100-watt regular light bulb, the cardboard part of a TP roll and a few other basic things. Obviously we'd use steel with these bulbs but once we had a fine laser point, we could use a thick fiber optic wire or even just focus it into a condensor directly. Seems pretty doable to me, I'd try but lack of $ to work with does me little good.

[Guy Grotke]

I think maybe you just made a light collimater. To make a laser, you need some material that can actually "lase", and something that can pump enough energy into it to get it up to that state.

Like a microwave klystron stimulating a tube filled with CO2, or a xenon flash tube stimulating a crystal. Or far, far cheaper: electricity stimulating a semiconductor (ie. a laser diode).

Making a projector using red, green, and blue lasers is not hard at all. The simplest designs use spinning mirrors to scan across the image field and modulate each laser's intensity to form the different colors at each point on the screen. It is just VERY expensive, until green and blue lasers get down to the price of red laser diodes.

[mathias]

There was a thread on here about using multiple fluorescent ballasts and starter to run MH lamps. Not a good idea, but you might get it to work. If I was trying to do that, I would use a digital scope to capture the volatge and current of a standard 400 Watt ballast, cap, and igniter circuit, then see if I could match it. Just hooking them up with no knowledge of what you need is asking for trouble. These are not just simple inductors; They are constant power autotransformers with a specific behavior to the igniter actions.

As the constructor of the diy-ballast you are talking about, I can say it works fine. Before I built the ballast I had study hid-ballast and hid-lamps in two years. The diy-ballast work as the most simple hid-ballast "plain reactor".

A simple "reactor" ballast have some disadvantage: "With these ballasts the input line voltage should be controlled to within ±5% because the resultant lamp wattage will vary ±12%. However, this fair degree of lamp regulation is acceptable in many applications. In addition, in the event of a momentary power drop where the line voltage dips below 75% (e.g. to 180 volts on a 240 volt system), the HID lamp may extinguish.", taken from the hid-document below.

There are many more models of ballasts, specially if the main voltage is 120Volt, then you must first transform up the voltage and then use the reactor as the current limiter, this ballast is
namned "High Reactance Autotransformer".

My ballast design works and do not harm the lamp, it is measured and tested for a long time.

BUT I can not take responsibility, if people are using other parts than I have written, as some people now have done, and of course it´s dangerous then. If you have over powered the lamp one time it will never return to it´s normal level again, it´s bye bye to that lamp. The thing that is not good with the diy-ballast is that it does not have heat protection fuse (some reactors have), so you have to complete with that.

I was thinking of buildning an electronic-ballast, because they will be smaller cheaper and more safe and fast ignition. It´s actaully very simple to build an electronic ballast, with a normal
transistor bridge on =400V as is switched with a frequence of 200-300Hz, why not more ? Searchthe web!. But even if I will build this electronicballast I will NOT show it on this forum,
because it´s dangerours and you must have the right knowledge, and it has been proved that people here don´t have that knowledge, some have.

http://www.hydroponics.net/productdo...cket_Guide.pdf

[mathias]

The simple answer is no you can´t, you can only do that with "plain reactor" ballasts (two connections ballasts) and the power will not be doubled, it´s much more complicated.

[Guy Grotke]

I have noticed that the manufacturers of most of the high-performance MH lamps (ie. 5000-6000 K color, small package, short arc) say that an electronic ballast in required. A simple inductive ballast is not "smart enough" to always start, run, and protect these MH lamps.

Larger MH lamps meant for lighting parking lots, etc. can use the simple inductive ballasts because these lamps are designed to be more tolerant of imperfect power conditions.

You can make an inductor-based ballast have more complex behavior by adding additional components: An ignitor for starting pulses, a capacitor for power factor correction, a safety fuse to prevent thermal runaway, etc. At some point it just gets so expensive that an electronic controller makes more sense. With a microcontroller in there, you can add some nice features for free: Automatic fan control, hours of use counter, remote on/off. dimming, restart lockout period, safe shutdown if the lamp pops, etc.