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Multiple Flash Unit

By Jock Orr

This unit is intended for situations where it is inconvenient to use the ordinary flash lighting techniques.  In effect, it is a lightweight studio lighting outfit which enables the cave photographer to position his lights as and where he wants them.  The general arrangement is shown on the next page and the Central Box circuit diagram, also on the next page, is quite easy to follow.

The electrical components may be obtained from any amateur radio shop, and the flash bulb sockets from a photographic dealer.  The reflectors are made from scrap headlamp reflectors, and although the parabolic form of the reflector is designed to cast a beam, this can be altered to cause the spread of light by trial positioning of the flashbulb socket before final fixing.



Apart from the major expense of the cables, the cost of the unit amounts to about £3, and while a description of its construction may be of general interest, it will only be of a particular interest to the serious cave photographer who will recognise immediately the technical advantages to be gained form this equipment.

N2/P2  Battery 22½ - 30 volts

N1/P1  Battery 22½ - 30 volts




Switches ‘UP’ 25v fires 1 to 3 Flash.


Switches ‘DOWN’ 50v fires 4 to 6 Flash.

Switch ‘A’  Double Pole

Switches ‘B’ & ‘C’  Instrument switches

R1 – Resistor 3,300 OHM

R2 – Resistor 5,600 OHM

C1 – Capacitor (electrolyte) 25-30v. D.C.  100mf

C2 – Capacitor (electrolyte) 50-60v. D.C.  100mf

S.W.1  Miniature Press Switch.

S.W.2  Miniature Press Switch

L.1  Miniature Signal Bulb

L.2  Miniature Signal Bulb

The control box consists of two tobacco tins soldered together with cut-outs for mounting the components shown in the circuit diagrams.  All sockets and plugs are standard 2 pin, flat body, ex-Woolworth’s. All electrical connections should be soldered.  The cable and flashbulb circuits are SERIES.  Operating instructions and suggested layouts will appear in a later issue of the B.B.