Strobists eat your heart out

I saw some used honda generators for sale at a local store. They are super quiet, fairly light, and can provide power for hours. Has anyone used them for flashes? I am thinking they would work great. Here they are. 29 lbs, but at least you can use it for lots of things besides photography.
 
So to Adam, No...you probably can't just use Motomaster power unit because I doubt it's a Pure Sine wave so the 'dirty power' would likely damage your lights (probably significantly reduce the life of the bulbs, from what I've read).

Where did you read that? Do you have a link to the source?

I could not imagine that this would be an issue as the power source is not in direct contact with the bulb. The source voltage charges a capacitor bank to store the power required for the flash burst. When the flash fires the bulb is ignited by a 3000V spike, and keeps arcing till it's cut off from the capacitor (or the cap is flat). The circuit which stores the energy for the flash is pretty much the same as you would see in a computer powersupply, just that there is far more energy storage taking place.

There are really very few devices that don't run off a cheap modified sinewave inverter, and they are mostly devices with AC motors such as sewing machines and some fridges. If the flash fails it would most likely be a capacitor dying, and a warranty repair given that the harmonics which could potentially kill them are present on mains voltage as well in many areas and thus should be accounted for by the designers regardless.
 
I saw some used honda generators for sale at a local store. They are super quiet, fairly light, and can provide power for hours. Has anyone used them for flashes? I am thinking they would work great. Here they are. 29 lbs, but at least you can use it for lots of things besides photography.

Just curious... why not use generators as CxThree suggested?
 
Where did you read that? Do you have a link to the source?

Ok, I couldn't quickly find any info on why 'dirty' power would harm the bulbs...but I do remember reading that somewhere. I was able to dig this up from somewhere though.

I'm not familiar with the input circuit of some of the monolights used but there are reasons why a sine wave must be used for a power source.

One might be that inverters (modified sine wave (stepped actually)) can't handle the capacitive load of the flash charging. With a sine wave input you will get progressive charging of the flash capacitors as the sine wave climes. With a stepped output of non-sine wave inverters you have a sudden voltage jump and you are applying that to a capacitive load that looks like a short.

Modified sine wave inverters work great with resistive loads. Also with inductive loads the stepped output of the inverter will will not produce a sudden current jump because the load is inductive. But capacitive loads on these kinds of supplies are evil.

You may say that computer power supplies are capacitive and they work. Yes but you are only replenishing the charge at the top of the cycle. Flash power supplies are always discharged and constantly providing a load that looks like a short to square waves.

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trw_nanaimo says:

Nothing can cook unless excess current or voltage is available in excessive unregulated amounts.



Actually, since he's asking whether to buy a true sine or square wave inverter, the real question is what type of power supply his strobe has.
There are three likely types: Transformer-rectifier, switching or flyback, and voltage multiplier.

If it's a Transformer-rectifier type, it will be very heavy, and you MUST use a true sine inverter since the first thing (other than the fuse and power switch) in the circuit will be a large transformer. A square wave fed into a large inductor (the transformer) will result in extremely high peak voltages (but at low current) pulsing through the circuit, frying any semiconductors, and possibly being a safety hazard.

If it's a switching or flyback power supply, you can probably use either type as the first thing in the circuit will be a bridge rectifier, followed by a capacitor bank, and it will not care about the shape of the waveform.

If it's a voltage multiplier, it might or might not need a sine wave, depending on how much wiggle room there is in thermal design (the diodes will be seeing what they expect as peak current as average current if you feed it a square wave).

How do you tell them apart?

If it has a wide input voltage range like 100-250V, 50-60Hz, it's probably a switching type. (it may or may not also make a high-pitched whine when charging) either

If it only works on one voltage (or has a 115V-230V switch) and is heavy for it's size, it's probably a transformer-rectifier type. (it may make a low pitched hum when charging) true sine

If it only works on one voltage, and that voltage is 220~250V, and it's very light for it's size, it may be a voltage multiplier. possibly true sine, possibly either

If it takes an electrician and a service call from the power company to plug it in, it's probably a rectification-direct-charge type, and it's permanently installed in a stadium anyways, so not really portable. three phase
 
Just curious... why not use generators as CxThree suggested?
I think generators are an option, as long as they are good ones that give you nice clean power. But there is a big difference between using a battery & inverter that is small enough to be attached to a light stand...and running a gas powered generator.
 
Low end generators? Likely becuase the higher costs, increased noise, longer cables and unstable power delivery. Also added costs for gas to run them. They work, if you choose carefully... but wow, I cannot imagine using one. I go to one location, take 100-150 shots, move to the next, shoot and so on. I would be DEAD tired from lugging that all around over a simple Vagabond battery pack or two... lol
 
True. It's not a very light solution, but it's got versatility. The honda ones are super quiet too. I was thinking on getting one, but using it on a luggage type rolling carrier. WIth straps, I can mount the generator and all my equimpent for rolling around. It should be a quick setup from there.

My reason for looking at these is tailgating. I do that regularly during football season. I was just thinking about leveraging it for photography so that I could get multiple uses out of it.
 
Ah.. I understand.

I was under the impression that you would have to carry several of those battery+inverter units which wouldn't be any lighter or easier to carry than a generator. I was also considering that a "recharge" is as easy as a quick trip to the local gasoline station which is a whole lot easier than trying to recharge batteries offsite. I used to have a generator at my hold house (lots of power outages). It would run practically all night and it was pretty darn quiet. Just need a long enough cord to keep it away from the house.
 
Ahhh very true. Although each of these scenarios would be more likely to damage the inverter than the flash head, and definitely not the bulb. Not a good thing in any case.
 

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