royall_berndt Posted January 5, 2021 Share Posted January 5, 2021 I used to see plans in.magazines for constructing flash triggers. Anyone have those plans? Link to comment Share on other sites More sharing options...
BeBu Lamar Posted January 6, 2021 Share Posted January 6, 2021 I have no idea what type of trigger in that magazine but I have seen other optical trigger using Light Activated SCR. Link to comment Share on other sites More sharing options...
royall_berndt Posted January 7, 2021 Author Share Posted January 7, 2021 The magazine trigger used an LA SCR. Link to comment Share on other sites More sharing options...
rodeo_joe1 Posted January 8, 2021 Share Posted January 8, 2021 The magazine trigger used an LA SCR. Good luck finding one of those these days. I built an opto-slave years ago using a photodiode, a transistor and a low gate current SCR. Plus a couple of resistors, a zener diode and a capacitor to power the thing from the flash trigger voltage. These days it would cost more in components, connectors and a transparent housing than you could buy one for. Sunpak and other makers sold little 'peanut' slave triggers with a rubber sucker for mounting. They're quite plentiful and crop up for sale quite regularly and cheaply. Link to comment Share on other sites More sharing options...
harris_austin2 Posted February 9, 2021 Share Posted February 9, 2021 Afraid Joe hit the nail on the head. I had the same idea years back and couldn't find a LASCAR or LA SCR anyplace. Link to comment Share on other sites More sharing options...
glen_h Posted February 10, 2021 Share Posted February 10, 2021 As far as I know, this is the favorite use for LASCRs. -- glen Link to comment Share on other sites More sharing options...
rodeo_joe1 Posted August 5, 2021 Share Posted August 5, 2021 I came across my old homemade slave trigger the other day. So for the sake of completeness; here's a picture of it and its CCT diagram. And the circuit - The MRD14B is a photo-darlington transistor. Good luck finding one of those these days! As well as sourcing a C-106 sensitive gate SCR... or a small transparent plastic box... or a male line P-C plug. I suppose a photo-darlington could be fabricated by cutting the top off a metal TO-18 cased device and filling it with transparent epoxy resin. But really, is it worth the cost and trouble? Unless constructing junk-bin electronics is your idea of fun.;):rolleyes: Oh, nearly forgot. The circuit was designed to be 'self-powered' using the small current available from an old high trigger voltage flash. Hence the 1.5 megohm resistor. With a modern low trigger voltage flash that resistor could be replaced with a much lower value, or even with a short. And any consequences from using the above design are entirely at your own risk. I take no responsibility! 1 Link to comment Share on other sites More sharing options...
glen_h Posted August 5, 2021 Share Posted August 5, 2021 I think you can now get photo-SCRs, so maybe no need for photo-darlington My first real electronics project, real enough to get in a box, is (I still have it somewhere) a touch switch from Popular Science. It uses the C106B1, which looks like the one you have. I built that in about 4th grade, after mail ordering the SCR and the NE-83 from Allied Electronics. -- glen Link to comment Share on other sites More sharing options...
glen_h Posted August 5, 2021 Share Posted August 5, 2021 Otherwise, you get the reverse PC from a PC extension. I still have the PC cord for my Vivitar 283. One could cut off the PC end, and splice directly onto the rest of the cable. Or splice directly onto a hot-shoe to PC adapter. -- glen Link to comment Share on other sites More sharing options...
glen_h Posted August 5, 2021 Share Posted August 5, 2021 (edited) It seems that the MRD14B is so old, it is in a museum! MRD 14B, Tube MRD14B; Röhre MRD 14B ID67140, Transistor Three photo-darlington from Digi-Key: Sensors, Transducers | Optical Sensors - Phototransistors | DigiKey Edited August 5, 2021 by glen_h -- glen Link to comment Share on other sites More sharing options...
glen_h Posted August 5, 2021 Share Posted August 5, 2021 The touch switch is in this one: Popular Science I used a regular box, though, and then built a new box for it in metal shop in 7th grade. -- glen Link to comment Share on other sites More sharing options...
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