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Old Feb 22, 2006, 6:21 AM   #1
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There is a Sunpak 383 thyristor superflash up for bid on e-bay. Is a thyristor a certain model? Does anyone know? The seller couldn't help me.
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Old Feb 22, 2006, 6:39 AM   #2
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I do not what is in this case but thyristor is an active electronic element - like - transistor, trigger...
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Old Feb 22, 2006, 7:26 AM   #3
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I don't know thecomplete answer in your case, but let's try:

A thyristor is an electronic device designed to control high power/energy, these parts are used in a "dimmer" = phase fired controllers.

see: http://en.wikipedia.org/wiki/Thyristor

Flashes with thyristors usually have afine control of the released energy and many of them can feed back the unused energyto the batteries.

..just my two cent


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Old Feb 22, 2006, 7:34 AM   #4
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That is the flash you want.

Mine is a thyrister also.
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Old Feb 22, 2006, 10:05 PM   #5
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Thank you one and all. Is it similar to the regular sunpak 383. They seem to be different.
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Old Feb 23, 2006, 9:41 PM   #6
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A thyristor is a kind of electronic clamp that shuts off the flow of electricity to the flash tube.

What happens is that the batteries charge up a capacitor (which is an electronic storage component) to a very high voltage. When the flash fires, the charge stored in the capacitor flows to the flash tube causing it to glow brightly. In a normal, manual flash, the flash tube glows until the capacitor is fully discharged (which happens in a small fraction of a second -- typically under 1/1000 of a second or less). If a flash has a thyristor, it also has a sensor that can sense when the flash tube has produced enough light to proper expose the scene. When the sensor signals that enough light has been emitted, the thyristor cuts the flow of electricity to the flash tube, turning it off and saving whatever charge is left in the capacitor. This allows the batteries to only "top off" up the capacitor replacing only the amount of the charge that was used. This saves battery power and also allows for quicker recharge times for scenes that only require a small amount of light.

Back in the bad ol' days when the first automatic flashes came out, they did not cut off the current flow when the sensor was satisfied, but rather redirected the charge from the flash tube to an internal "quench" tube that absorbed the rest of the capacitor charge. When thyristors first came out, they were a real selling point for the battery and recycle time advantages listed about. Now-a-days, however, most all auto flashes have thyristor circuitry.
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