philip_weatherley1

<p>Hi all you fellow Metzbotherers<br> ...after reading the above and experimenting here's the most recent findings:<br> Note: the flash was set up on a tripod and the subject constant throughout. All batteries freshly charged to makers spec using a bench power supply with V and I limiting and a timer.<br> The most rapid re-cycle-times are obtained using Nickel Cadmium batteries - in my case "Sanyo Cadnica" 700mAh.<br> The high-capacity (2.6Ah) NiMH "Energiser"and "Duracell"batteries have higher internal resistance and are not very good in this application for that reason. Their high capacity not really much of a bonus. 3sec NiCd vs 10s re-cyclle times with NiMH. Subjects get bored, shots are missed.<br> Fresh Alkalines (Duracell Pro-Cell) are intermediate and also give a slow re-cycle time. We must ruefully accept that nasty poisonous NiCd are the boys for the job, lesser capacity notwithstanding.<br> Those jolly gents above who proclaim that the existence of differing contacts on the battery packs is a nicety one can ignore are wrong. Those using NiMH are getting away with it as NiMH has a high internal resistance and cannot provide the current for a rapid re-cycle thus saving the bacon of the transistor doing the work in the oscillator circuit. (looks like BD233 or maybe 238 on my ratty jpg circuit diagram). It seems plain that the metzmen would not have gone to the trouble of doing two different battery holders and contacts had there been no problem with NiCds roasting the oscillator transistor.<br> Testing the Cadnica 700mAh batteries an in alkaline battery holder with an ammeter in series shows a peak of around 6 amps*. (*a transient estimated looking at the meter - not an oscilloscope trace as I lack a precision 0.1R resistor) Transistors BD 233 and 238 are 2A transistors - says 6A peak at <5ms. <br> Bottom Line.<br> 1) Fast cycling times need NiCd AND the right contacts in the flash.<br> 2) Anyone accepting long re-cycle-times can use a high capacity NiMH in the Alkaline batt holder.<br> 3) Lastly, to fulfill 1) you need an empty or secondhand NiCd holder or do a naff conversion job on the alkaline holder to move the contact. Given the average joe's manual dexterity I shiver at the thought of battery pack capable of around 10A lurking and shorting-out to produce melted plastic and smoke.<br> Mind you - it might make a good photo eh?<br> Phil Weatherley UK</p><div></div>