Vivitar 2000 Slave Flash (DF500 Board Version), (Low Power Mod Data) Options

[dkirk]

I just went back and tested the Vivitar 2000 "Low Power Mod", and amazingly it just about matches the performance of having the capacitor totally isolated from the circuit (updated graph attached).

The “Low Power Mod” involves removing a 10 K ohm resistor that feeds the “bounce back circuit” and associated zener diode, and this reduces the load on the capacitor which therefore reduces the rate at which the capacitor discharges. The “Low Power Mod” also involves removal of the Neon lamp, or the 1 Meg Ohm resistor that is in series with the Neon lamp.

The “Low Power Mod” did result in the capacitor being charged up to a maximum voltage just slightly higher than the “non modified Vivitar 2000” (approximately 6 volts higher), but this is not a significant amount (charged up to 332 Volts using a 5.41 volt power supply).

Elimination of the “bounce back circuit” causes the slave to discharge down to around 65 volts after the slave is triggered (similar to running the slave in “manual” mode), and this causes the slave to encounter high inrush current when recharging after each trigger event.

The main concern I now have is the inrush current. The inrush current exceeds 2 amps when using 4 NiMH batteries when charging a totally discharged unit, and this exceeds the 2 amp continuous current rating of the Vivitar 2000 inverter transistor. Including a 0.47 ohm resistor (2 watts or larger) in series with the battery results in a peak in rush current of 1.889 amps which is a reasonable value. The high inrush current may also be hard on the inverter high voltage transformer, so limiting the current is a wise thing to do.

Based on the above data, I will use the “Low Power Mod”, but will also include a 0.47ohm resistor in series with my battery. The addition of the 0.47 ohm resistor will slow down the rate of charge, so slave charge time will have to be adjusted accordingly.

It would be nice to slightly reduce the voltage that we charge the capacitor to since we are currently charging it close to its maximum rated value. Reducing the capacitor voltage slightly will also help to lengthen the life of the strobe tube. An alternative solution would be to change the capacitor to a higher voltage rated capacitor with possibly slightly lower capacitance.

Hope everyone interested in the Vivitar 2000 flash has found this information helpful.
Don Kirk

This post has been edited by dkirk: Aug 12 2006, 01:42 AM

Attached File(s)

 Vivitar_2000_Capacitor_Discharge_Rev1.pdf ( 44.87K ) Number of downloads: 44

 

[treetop]

I am sure I am not alone I do appreciatte the effort that you have put into not only doing this but sharing it with us It makes it easier to understand for me the workings and what is going on with the slave Thanks for some great work !!

[Tinhorn]

what TreeTop Said!

I love circuit analysis like this, thanx. I guess you do have the Schematic of the Vivitar 2000 right! I think I have it if you don't

Tinhorn

[212]

Same thing goes for me too...thank you for the work and sharing it. You are definitely an asset to the site.