LCOLLINS1989 Posted March 22, 2011 Share Posted March 22, 2011 Hey guys, First off, I just stumbled across this forum and it looks great so I joined! Will definitely keep checking back for information. I know this is a long shot as this isn't what this forum is for, but I'm having issues with a strobe light. I bought one for my band to use for live gigs however it did not have a footswitch function. I have repaired guitar amps and built FX pedals before so my understanding of electrical wiring is slightly better than basic. I wondered what is the best way to wire this footswitch. My understanding was that all I need to do is interrupt the power and then reconnect it with the footswitch. My question is where is the safest place to interrupt the power? As far as I can see the circuit basically goes mains voltage - ne555 timing circuit - flash rate pot - LED's I figure that I'd need to interrupt the power before the timing circuit as not to damage the ne555 chip, is this correct? Ideally I'd like to avoid interrupting mains voltage due to the dangers involved, and a DMX controller seems excessive for one strobe light. I only ask as I've already tried twice, the first time I think the chip got damaged as the light just stays on and doesn't flash, and the second time I got a mild electric shock Thanks again! Lewis Link to comment Share on other sites More sharing options...
themadhippy Posted March 22, 2011 Share Posted March 22, 2011 First of be careful rummaging around in strobes,there's lots of high voltages roaming around that can jump further than bog standard mains,also its no uncommon for them to derive the low voltage from a simple resistor diode arrangement.As for foot switch triggering without a circuit diagram its a bit of a stab in the dark,you may get away with holding the 555 reset pin low. Link to comment Share on other sites More sharing options...
Wol Posted March 22, 2011 Share Posted March 22, 2011 my understanding of electrical wiring is slightly better than basic. <snip>think the chip got damaged<snip>I got a mild electric shock You can make those "electric shock" machines using an old camera flash mechanism but without the flash bit *-). I think you've got part of the way there.... What type of strobe is it? What controls does it have on it at the moment? What control do you want of it in the end? do you want the footswitch to enable blinder mode? Single flash? etc... Interrupting the mains isn't something you really want to be doing I'd say, and definitely not anywhere near a 555 unless you've got the correct circuitry to 1) switch the mains signal and 2) rectify the incoming mains to supply the circuit. Depending on the make/model of the strobe, there will be various trigger signals inside that you may be able to tack onto but playing about with a soldering iron inside a strobe isn't something I'd personally want to do, especially if you're taking this unit into other venues. Don't think that many people would be appreciative of someone turning up with a strobe and some home bodged wires coming out of it... The question has to be asked: If you wanted footswitch control, why didn't you save yourself the hassle, and buy a strobe which had remote trigger functionality built into it in the first place? Link to comment Share on other sites More sharing options...
LCOLLINS1989 Posted March 22, 2011 Author Share Posted March 22, 2011 So far I haven't messed around with a soldering iron too much for this exact reason. It's an LED strobe light, that has a rate control and an on/off switch. All I want to be able to do is switch it on and off via the footswitch. I've drilled a hole to install a jack plug to contain the wiring modification safely. I can extend this hole to incorporate other connectors. I didn't buy this strobe, my singer did. In my ignorance I thought this would be a simple case of wiring a footswitch between the circuit and the LED's. However there doesn't seem to be many strobe lights that have a remote trigger oddly enough... At least I haven't found many Link to comment Share on other sites More sharing options...
Brian Posted March 22, 2011 Share Posted March 22, 2011 So the 555 will be running as an Astable oscillator. Google that to see the circuit. The output from the 555 is on pin 3 and will either go to the LEDs directly or will drive a transistor/fet to drive the LEDs. I'd interrupt the signal out of pin 3 with a normally closed footswitch. You could also turn the 555 on and off by switching pin 4. It's normally held high but if you chopped the pcb track going to it and pulled it low with a resistor, 1k will do, when you pull it high (ie to pin 8) via the footswitch (normally open) the 555 will start. [EDIT] just like this... Link to comment Share on other sites More sharing options...
LCOLLINS1989 Posted March 22, 2011 Author Share Posted March 22, 2011 Thanks Brian that's fantastic! (especially the diagram!) So you'd personally interrupt pin 3, rather than switching pin 4 and 8? Also, just to double check.... A DPDT Latching footswitch will work ok? (only using 1 side) Link to comment Share on other sites More sharing options...
Brian Posted March 22, 2011 Share Posted March 22, 2011 I'd start by using the circuit I posted and tracing out the circuit on the board. Check where Pin 3 goes. I *suspect* it goes to a transistor/fet. If you've got a DPDT latching footswitch I'd probably use the pin 4 option but switch the push-button shown in the circuit with the 10k resistor. Like that, with nothing plugged into your jack, the strobe will still work. The external switch then turns the 555 off to kill the LEDs. The only fly in the woodpile would be that when the 555 is stopped the LEDs *might* turn on depending on how they are driven. I think we need to establish what happens from pin 3 onwards. Link to comment Share on other sites More sharing options...
LCOLLINS1989 Posted March 22, 2011 Author Share Posted March 22, 2011 Ok mate, I'll have a look in a bit when I have some time and work out exactly what happens between the chip and the LEDS Thanks again for all your help :) Link to comment Share on other sites More sharing options...
LCOLLINS1989 Posted March 23, 2011 Author Share Posted March 23, 2011 Hey, sorry it took me awhile, got busy yesterday! You were right Brian! Pin 3 goes to the base of one transistor. The collector of the transistor goes to the base of another transistor. Then that collector goes to the LED's. Pin 4 and 8 are indeed connected on the circuit board, with some resistors coming off the same tracks.. Hopefully this all makes some sense? Link to comment Share on other sites More sharing options...
cameroncoats Posted April 1, 2011 Share Posted April 1, 2011 The only fly in the woodpile would be that when the 555 is stopped the LEDs *might* turn on depending on how they are driven. I think we need to establish what happens from pin 3 onwards.10k pull down on pin 3 should solve this? Link to comment Share on other sites More sharing options...
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