MogLite Posted February 22, 2006 Share Posted February 22, 2006 Is there some kind of in-line widget I could use to make a warning lamp flash ? Oil pressure for example Using a flashing LED is not an option as I want all the warning lights to be the same shape, and I have a bunch of them already. An indicator flasher seems a bit overkill, I don't even know if it will work with such a low current draw. Got to be an easy one Quote Link to comment Share on other sites More sharing options...
TomG Posted February 22, 2006 Share Posted February 22, 2006 I've heard of some of the hillrally guys using a defender brake light mounted on the dash & a buzzer for oil pressure warning. Can't miss that! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted February 22, 2006 Share Posted February 22, 2006 Andy, Series flasher unit might work, 2 wires, small and cheap. Failing that I'm sure I can knock something up for you Quote Link to comment Share on other sites More sharing options...
siggy Posted February 22, 2006 Share Posted February 22, 2006 Try this and change leds for bulbs or place a relay in place of led to power a more powerful circuit http://ourworld.compuserve.com/homepages/g_knott/elect25.htm Quote Link to comment Share on other sites More sharing options...
02GF74 Posted February 22, 2006 Share Posted February 22, 2006 Andy,Series flasher unit might work, 2 wires, small and cheap. Failing that I'm sure I can knock something up for you 'fraid not; you need to load it with 2 21 W bulbs; if omne of them goes, the units stops flashing. how many bulbs you want lit? using flasher units could be quite bulky. what is the mode of bulb operation? you and it off or flashing or is there a third mode when it is on continously? Quote Link to comment Share on other sites More sharing options...
MogLite Posted February 22, 2006 Author Share Posted February 22, 2006 'fraid not; you need to load it with 2 21 W bulbs; if omne of them goes, the units stops flashing.how many bulbs you want lit? using flasher units could be quite bulky. what is the mode of bulb operation? you and it off or flashing or is there a third mode when it is on continously? Siggy - way too complicated I'm afraid - I can't be fagged with that 02 - oil pressure, engine water temperature and possibly transmission temp are all things that I have to act on immediately Off and flashing are the modes I reckon - can't see the value in complicating it with a steady state. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted February 22, 2006 Share Posted February 22, 2006 Andy, I reckon I can come up with a small circuit to do it, the only thing I'd want to know really is what the sensor does in it's "alarm" state - does it go open circuit, +12v, or short to ground? Edited to add: Do you mind if the warning lights are -ve switched (permanent +12v to them and the ciruit earths the other leg) 'cos that's easier Quote Link to comment Share on other sites More sharing options...
Turbocharger Posted February 22, 2006 Share Posted February 22, 2006 Lateral thinking - save the 'attention-grabbing' flashing lamps and deafen yourself instead. why not earth all the lamps through a buzzer, and fit a push-to-make switch in parallel with the buzzer to short it out when you expect the noise, such as when the engine's off (and ignition's on). Quote Link to comment Share on other sites More sharing options...
Mark90 Posted February 22, 2006 Share Posted February 22, 2006 Never hear a buzzer, have you seen those cans he's running Quote Link to comment Share on other sites More sharing options...
Outrage Posted February 22, 2006 Share Posted February 22, 2006 How about loading a flasher relay outputs with resistors as ballast to replace the flashing lamps? still expensive and complex though unless you've got a spare lying around. RS Components do 12VDC multifunction relays but they tend to be expensive and you will have to trawl through the various modes to find one that will meet your requirement. I tend to use OMRON they are a good make. Maplin Electronics (www.maplin.co.uk) sell an MK111 Adjustable timer with relay output for £3.99 although you will probably have to assemble the kit although its only got a few components. It will come with a pre-made Printed circuit board you just have to solder on the few components. Much simpler than assembling Siggys flip flop circuit and it will drive a few lamps without any modification. Part number VT27E The time base for this module is a pulse time of 0.5-5 seconds with a pause time of 2.5-60 seconds. its capable of switching 5A so is more than adequate to operate a few flashing lamps. the instructions are available at: http://www.velleman.be/downloads/0/manual_mk111.pdf Hope this is ok, Cheers, Quote Link to comment Share on other sites More sharing options...
rtbarton Posted February 22, 2006 Share Posted February 22, 2006 Rather than have each bulb with its own flashing device, provide a flashing supply from one of the magic circuits above and use it to supply the warning lights. That way they'll all flash in unison. Quote Link to comment Share on other sites More sharing options...
MogLite Posted February 22, 2006 Author Share Posted February 22, 2006 Blimey - I thought sticking a capacitor or similar in-line would do it. Still some great ideas. I particularly like the "all flashing together" from Mr Barton Fridge - I don't know how the sensors behave to be honest - I'll find out - if I can find 'em The overheat warning will come from SimonR's x-fan. I'll be using this diagram Top of page 2 I stared at it for ages last night, and I just had to bow to Simon's superior intelect Buzzers I'm trying to avoid - I expect it will be noisy enough Quote Link to comment Share on other sites More sharing options...
geoffg Posted February 22, 2006 Share Posted February 22, 2006 Hi I use tail light as warnings, cant miss them Quote Link to comment Share on other sites More sharing options...
02GF74 Posted February 23, 2006 Share Posted February 23, 2006 How about loading a flasher relay outputs with resistors as ballast to replace the flashing lamps? still expensive and complex though unless you've got a spare lying around. you'll need some hefty resistors = expensive plus wasteful of amps. I thought about it as bit more last night and effectively the vellman circuit is what I would have done. In effect a 555 timers (yep, one of those again) that switches a relay. If you connect one end of the relay contact to 12 V; you have a 12 V flashing supply as the coiul is pulsed. Connect what was the 12 V to the bulb to it et voila. Ofcourse this assume that the sensor, and most of them do, work by switching to 0V when they come one. Having one ocsillaor for all the lamps means they flash at the ame rate and in unison; not sure if that is a requirement. To avoid any confusion with lamp wiring, what I would really have done is to make the 555 timer circuit and wire up a few relays. All you then have is to cut eiter lead to the lamp and connect to one set of relay contacts. The down side of this circuit is the relay(s) are always flashing when the ignition is on; I don;t know what the mtbf for the relays but guess around several million cycles. So rough calc at 3 times per second flash rate, assuming 1,000,000 cycles is only about 100 hours, not enough IMO. (solid state switch or a more cunning circuit would solve that). Quote Link to comment Share on other sites More sharing options...
rtbarton Posted February 23, 2006 Share Posted February 23, 2006 You don't need a relay for each circuit, just one to supply "12 volts flashing" and use this to supply all your warning lights. I'm sure you don't even need a relay at all, there must some electronic device on the market now that the transistor is gradually replacing the thermionic valve. I realise some re-wiring may be needed, but I wish I'd thought of that idea before I wired mine up! Quote Link to comment Share on other sites More sharing options...
02GF74 Posted February 23, 2006 Share Posted February 23, 2006 ... or can you just blink 3 times per second??? RTB - there are solid state switches but I lost the will to live trying to find them on maplins website. Quote Link to comment Share on other sites More sharing options...
mattD110td5x Posted February 23, 2006 Share Posted February 23, 2006 When I were a lad.... All the christmas tree lights were in series, and the bulb at the very top, where the fairy was, could be swapped by dad for a special flashing bulb. "most" low voltage bulb types are available as a flashing alternative with a bimetallic strip. you may have to look at industrial signal and instrumentation suppliers. It won't be a 10ppm crystal locked national timing standard, but it will attaract your attention... start slow maybe 1 flash a second and speeds up to 2 flashes a second once it warms up. ttfn Matthew Quote Link to comment Share on other sites More sharing options...
minivin Posted February 23, 2006 Share Posted February 23, 2006 what you want is a slow rate oscillator circuit if you want to build your own, An Op-Amp and a few capacitors and resistors can do that. or as stated above a 555 timer and a resistor bank to provide the required frequency. The indication bulb I take it is about 0.1W? that means as noted above about the dropper resistors you would need to drop pretty much 24Watts worth. That means you would need a power resistor for such a power dissepation of about 50mm length by 30mm square section which is bulkhead mounted via a base: Quote Link to comment Share on other sites More sharing options...
minivin Posted February 23, 2006 Share Posted February 23, 2006 An Op-Amp and a few capacitors and resistors can do that. Just remembered what the circuit was called, a Wien Bridge Oscillator Quote Link to comment Share on other sites More sharing options...
rtbarton Posted February 23, 2006 Share Posted February 23, 2006 You could use a flashing LED to drive a power transistor or some such device. Why not make it flash at 120 ppm and use it to drive relays to operate the flashers? This will obviate the need to buy a heavy duty flasher that can drive hazards and trailer lights. You'll have to rig up some form of warning for the trailer flashers. Quote Link to comment Share on other sites More sharing options...
Turbocharger Posted February 24, 2006 Share Posted February 24, 2006 Trailer? Moglite? Is it a powered jobby like the military have? I think the towball might be a little high though - imagine the angle a caravan would travel at on the road... Quote Link to comment Share on other sites More sharing options...
02GF74 Posted February 24, 2006 Share Posted February 24, 2006 re: the power resistors; IMO an expensive overkill plus wasteful of amps. re: You could use a flashing LED to drive a power transistor or some such device. this may be workable; if the current through the device changes then putting in a sense resitor to switch on power transistors would be a neat and compact way of implementing Wien bridgem, 555 and other oscillators. I had saoid a relay is not ideal due to its finite life but having given it some more thought, the warning lamps are hardly ever going to flash so proabably much less use than indicators and those last for years so it should be fine. Moglite - has any of this helped? (Lots of suggestions/discussion but no real product at the end so far). If you are still no further at getting a circuit board made up, I can go to maplins lunchtime and get a flashing LED (kinda like that idea) and I have some relays at home so can knock something up to see it is if feasible and let you know from there. Quote Link to comment Share on other sites More sharing options...
Troddenmasses Posted February 24, 2006 Share Posted February 24, 2006 I think that the way I would do it is to take the ground for all of the bulbs that you want to flash, and route it through a 555 timer in astable mode. It would oscillate all of the time that it was powered, but when a bulb became powered, it would flash. You wouldn't need to change any bulbs, have any big relays or anything. All you would need is a very small box hidden behind the dashboard. with 3 wires going to it. Power from a switched supply (for the oscillator) ground, and a wire going to the ground of all of the lights you wanted to flash. Simple. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted February 24, 2006 Share Posted February 24, 2006 ...except where the sensor grounds the bulb, then you'd need a "flashing" +12v supply Quote Link to comment Share on other sites More sharing options...
MogLite Posted February 24, 2006 Author Share Posted February 24, 2006 ....Moglite - has any of this helped? (Lots of suggestions/discussion but no real product at the end so far). If you are still no further at getting a circuit board made up, I can go to maplins lunchtime and get a flashing LED (kinda like that idea) and I have some relays at home so can knock something up to see it is if feasible and let you know from there. TBH - it sounds an awful lot more work and complication than I was expecting. I just though flashing warning lights would be cool with the addition of a £1.99 Flash'yer'bulb whatsit. Circuits, wiring, timers all sounds a bit complicated for something that is going to be cover in mud for a hobby. Quote Link to comment Share on other sites More sharing options...
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