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