Breathing life into an old flashgun... Part 2

[Vortex]

Modifications to a Metz 45 CL-4 to allow the use of different power sources.

Disclaimer: This is not a DIY step by step guide. If you intend to modify any equipment of your own, ensure you fully understand what you are doing and are aware of any risks involved.

In it's standard form the CL-4 can be powered by a 7.2V rechargeable NiCd pack, 6 x 1.5V (9V) alkaline batteries, or a mains adaptor (N 22).

When running on 7.2V or 9V the batteries power an inverter to provide the necessary voltages the flashgun uses internally.




The Metz N22 mains adaptor connects using this 3 pin socket just below the head of the flashgun.

It delivers +18V and +350V directly and does not power the inverter circuit. The primary advantage of the N22 adaptor is the faster recycling times it provides.

For my own use I shall use a supply of 7.2V, for reasons that will become apparent later.

This simple modification allows the use of external power sources without the use of Metz accessories; although it's necessary to 'sacrifice' the existing alkaline battery holder.




This view is looking into the CL-4 battery compartment.

Contact with the pack or holder is via the three spring loaded pins, a common positive pin, and one for either 7.2 or 9 volt. Looking at the corresponding NiCd or alkaline battery holder the difference in connection is apparent.





This is the existing 45-39 alkaline battery holder after having dismantled, removed all battery contacts, fitted a suitable socket and reassembled.

This now gives me a choice of power source. For mains voltage use I'm using a simple power supply that I built based around an LM389K regulator IC. This is quite a versatile regulator, having minimal external component count, and fold-back current limiting. It is able to provide 5A at 7.2V, which is quite adequate to power the CL-4. The recycle time after a full power flash is approximately 11 seconds, not fast, but adequate for the use I envisage.




Output voltage set to 7.2V when on load. (The connector on the battery holder is not the one I finally used).




All finished.




This moderately sized heatsink for the regulator runs quite cool, even after prolonged use.




In use, together with a modified Vivitar 283, and a few more DIY bits and pieces. (No I don't normally photograph dangling nuts...)



Part 1 - The initial idea / reviving the battery pack. Breathing life into an old flashgun... Part 1

To follow...

Part 3 - Ditch those proprietary connectors / High capacity battery pack.
Part 4 - Fully variable power (flash duration) control.

[Kodiak]

(No I don't normally photograph dangling nuts...)

Very funny!
;-)