Slave Flash for Digital Cameras: Don’t throw away your old flashlight （2）

Published:2011/8/4 21:55:00 Author:Amy From:SeekIC

Udo Burret

Construction

Building this circuit is unlikely to cause problem if you use the printed circuit board artwork shown in Figure 2. Do pay attention to the orientation of the diodes, ICs and Tl. The phototransistor’s case is not unlike that of an LED. The collector terminal is near the flat­tened side.



Having finished the soldering work it’s a good idea to check if all components have been mounted correctly before switching on the power supply. In rare cases D2 will light immediately when the supply is switched on as IC1 will randomly activate one of its outputs. However, D2 must come on in response to SI being pressed briefly. Preset PI allows the input signal for the decade counter the adjusted. Some experimentation may be required before you find the optimum setting for PI:

-turn the wiper to the ’ground’ extreme position.
-press SI
-slowly advance the wiper of PI
-stop when LED D2 goes out
-back off a little in the ’ground’ direc­tion

Finally, a note on hooking up the exter­nal flashlight: pin 1 of K2 — connected to the anode of Thl and resistor RIO — should be taken to the centre contact of the flashlight socket.

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