Being new to this site I thought that I would try a simple basic circuit to get started. It fires the camera on the second flash (the taking flash). Also fires the flash on the third flash by throwing the switch. It can make this a permanent 2 flash by eliminating the "and gate chip"
Mon, 20 Sep 2010 11:15:05 +0000
here is a simpler circuit for a 2 flash adaptor. You could be ambitious and wire in a 7 segment display
Mon, 20 Sep 2010 12:39:52 +0000
Hi, geriatric. Thanks for updating these diagrams. But can you give us slightly more details on what is the purpose of these circuitry? It sounds like it triggers the camera to take a photo in the original post. What are some applications for this hack?
Mon, 20 Sep 2010 15:30:23 +0000
When I designed these circuits everybody complained about the 2 flashes fired by the on board flash or a flash on the hotshoe. Let me explain the operation of a 4026 chip. It is known as a decade counter as it obviously counts up to 10. There are 7 led`s in a segment display lettered as a b c d e f g. When the unit is switched on all segments go high and light,except g otherwise it would show 8 insteasd of 0.The first pulse from the photo transistor to the input of the 4026 sending b & c high showing 1. G stays low so no effect on the led or capacitor. The second pulse (the main flash puse ) arrives, this now sends a b d e G high. As g goes high the capacitor is charged and a brief pulse is fed to the gate of the 106 scr. This puts the scr on and the main flash discharges through the scr.
Mon, 20 Sep 2010 18:55:20 +0000
Here is a shot of the adaptor using a Vivitar flash. triggered by the on board flash. The green led lights on the second flash received. The red button is to reset the unit after a flash.
Mon, 20 Sep 2010 22:04:30 +0000
forgot to mention the 3 flash adaptor. The only difference is bsides the "G" connection there is a "C" connection to make both inputs to the "and gate" high thus charging the capacitor and pulsing the scr.
Mon, 20 Sep 2010 22:14:32 +0000
Oh I see. I'm starting to get you. So the circuitry bypasses the pre-flash, but allows the main flash to fire, right?
Wed, 22 Sep 2010 15:59:27 +0000
Exactly. I see nobody except you are interested in this project, so I will give it a rest.
Thu, 23 Sep 2010 06:32:34 +0000
Don't fret it. There are a lot of lurkers on this forum.
Thu, 23 Sep 2010 22:01:42 +0000
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