Vivitar 2000 (DF500 Board Version)

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Today I did additional peak current measurements on the Vivitar 2000 (DF500 board version) as follows :

1) Virgin unit right out of the box.

2) Modified the virgin unit in which I removed the DF-501 Board, the Neon bulb, R15, and R16. Also jumpered pins 1 and 2 on T2.

3) Took the modified unit in step 2 and replaced the original inverter transistor 2SC2500 B with a 2SC2500 A (the B is a higher gain version of the same transistor).


Test Results (using 4 AA NiMH batteries with open circuit voltage of 5.60 volts):



Peak Current = 3.46 amps (using 0.1 ohm carbon shunt resistor)

Peak Current = 2.49 amps (using 0.47 ohm wirewound and 0.1 ohm carbon shunt resistor)

Peak Current = 2.59 amps (using 0.47 ohm carbon and 0.1 ohm carbon shunt resistor)

Peak Current = 2.77 amps (using 0.47 ohm carbon resistor, and no shunt resistor)



Peak Current = 2.71 amps (using 0.47 ohm carbon resistor, and no shunt resistor)


Modified (including the use of new transistor 2SC2500 A)

Peak Current = 1.87 amps (using 0.47 ohm carbon resistor, and no shunt resistor)

Peak Current = 1.87 amps (using 0.1 ohm carbon shunt resistor)

Peak Current = 1.86 amps (using meter in current mode, and no series resistors)



1) Vivitar 2000 flash units (not modified) have very high peak current (DF500 board versions)

2) There is very little difference between using a 0.47 ohm wirewound or a 0.47 ohm carbon resistor to limit the peak current.

3) A series resistor should be used to limit the peak current of the Vivitar 2000 (DF-500 board versions). A 0.47 ohm series resistor or greater (2 watts or greater) is recommended.

4) Modification (removal of the DF-501 board and the low power mod) of the Vivitar 2000 flash unit does not noticeably change the peak current.


Notes :

1) In order to measure peak currents greater than 1.99 amps, I had to use a series resistor as a current shunt, and I measured the peak voltage across the shunt in order to calculate the peak current. I used the 0.1 ohm carbon resistor mentioned above in the tests as the current shunt, but used the 0.47 ohm carbon resistor as the current shunt in the tests in which I did not include the 0.1 ohm carbon resistor.

2) When using the lower gain transistor (2SC2500 A), it appears the transistor has more control of the peak current and the series resistor is much less of a factor (but it's still good insurance to use the series resistor).

3) The 2SC2500 inverter transistor (T5) is rated for 2 amps continuous and 5 amps peak current, but since our peak current is so broad we should try to limit the peak current to values closer to the continuous current rating.

4) If an SLA battery (or 5 NiMH batteries) are used to power the Vivitar 2000 (DF500 board version), then a larger value series resistor should be used.

5) All of the above current measurements were done with the flash unit totally discharged before charging.

6) I also tested the modified Vivitar 2000 unit using a 1N4007 diode in place of the FR107 diode (inverter diode), and detected no difference in operation.


Hope the above info helps in our understanding of the Vivitar 2000 that uses the DF500 board.



Edited by dkirk

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