ken collins Posted March 16, 2009 Share Posted March 16, 2009 I got a couple variable speed 25 watt cheap strobes I want to fire off a controller via a relay. I removed the scr from the ckt board, shorted the gate to either the anode or cathode, and hooked a couple wires to the anode and cathode, thinking when I touch the wires together, the strobe would fire. wellll, that didn't work. any suggestions? Link to comment Share on other sites More sharing options...
-klb- Posted March 16, 2009 Share Posted March 16, 2009 How certain are you that you have the three leads correctly identified? Haven't seen the circuit, but I would expect that leaving the gate floating would be the best option.. Note that you are probably playing with what could easily be 170 to 350 volts on those leads, so you are definitely playing at your own risk...I would also caution that some fixed rate strobes may easily charge capacitors over their rated voltage if they don't fire as often as in their original design.Personally, if I were doing it, I would look at keeping the original SCR in there, and adding an optocoupler SCR in series with the gate. Install the optocoupler and current limiting resistor inside the strobe, with good insulation on it, and then you are not bringing any high voltage outside the strobe case, and you can use a DC card channel to safely trigger the strobe..But, at these voltages, you did not hear it from me! Link to comment Share on other sites More sharing options...
Max-Paul Posted March 16, 2009 Share Posted March 16, 2009 ken collins wrote: I got a couple variable speed 25 watt cheap strobes I want to fire off a controller via a relay. I removed the scr from the ckt board, shorted the gate to either the anode or cathode, and hooked a couple wires to the anode and cathode, thinking when I touch the wires together, the strobe would fire. wellll, that didn't work. any suggestions?Ok, you removed the SCR from the strobe? Lets say that you are refering to the SCR on the strobe. Now you say that you shorted the gate lead to one of the other two leads of the SCR socket. What is this suppose to do for you? If anything, leave the gate lead floating. I do agree that you are playing with very high voltages, in the order of several hundred volts. Can you say tazer?With out getting a look at the circuit I am hard press to say what is going on. But with the gate shorted to the anode or cathode, maybe you are dumping the charge to ground. Once the gate is floated, I would think that the unit should fire. As for the cap over charging. Most circuits are built to supply only so many volts. And a good circuit will be rated to only built to a value less than the WVDC of the cap.Please my friend be very careful will working on a strobe. That cap can sit you one your arse, or kill you.Max Link to comment Share on other sites More sharing options...
-klb- Posted March 16, 2009 Share Posted March 16, 2009 I've sort of thought about changing some fixed rate strobes to remote trigger.. However, the cap that fires the trigger coil is not rated to the same voltage as the source that charges it. The reason it is not an issue is that the voltage on that cap is applied to a neon tube that breaks down and conducts through a series resistance to the SCR gate before the rated voltage on the cap is exceeded..So in this case, if you just replaced the neon lamp with a SCR, and failed to trigger at least as often as the original design, you could easily charge the cap beyond the rated voltage... Link to comment Share on other sites More sharing options...
ken collins Posted March 17, 2009 Author Share Posted March 17, 2009 I got the info for this off the "ChristmasinKent Web site. I removed the scr and put wires in the ckt board where the scr was. I essentially shorted all three terminals together,(being very careful). I was just taking a break from building kits, and thought I'd try, and see what happens. Just happen to have seven of these floating around, and thought I'd put em to use. Thanks for everyone's input and especially the safety notes. I was aware of the caps and the high voltage potential. Link to comment Share on other sites More sharing options...
sparky741 Posted March 17, 2009 Share Posted March 17, 2009 Here is a typical strobe circuit:http://www.aaroncake.net/circuits/strobe2.aspI would do what klb suggests and place an optocoupler in series with the gate to fire it externally. Wouldn't be much more than 3 or 4 bucks more in parts. Link to comment Share on other sites More sharing options...
BadSCR Posted March 23, 2009 Share Posted March 23, 2009 Here is something for the DIYer.I don't have the money but one of yall may.9.84" Long x 0.39" diameter , 1500watt Xenon strobe tube ,http://www.goldmine-elec-products.com/prodinfo.asp?number=G164691000VDC and 4KV for trigger, 5.6"L x .36" Dia , powerful Xenon strobehttp://www.goldmine-elec-products.com/prodinfo.asp?number=G16669 Link to comment Share on other sites More sharing options...
ken collins Posted March 23, 2009 Author Share Posted March 23, 2009 Thanks for everybodys input.. Did finally get back to this project tonight with an optocoupler. Worked like a charm.. Thanks klb, sparky, and Jeff and max-paul Link to comment Share on other sites More sharing options...
ken collins Posted March 24, 2009 Author Share Posted March 24, 2009 Hi Jeff, gonna use em as a shooting star effect. Wanted something brighter than a curtan strobe, or rope light. Although now that I have it figured out, the mind is wandering..... Thanks again for everybodys help. Ken Link to comment Share on other sites More sharing options...
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