ppa@hpldola.HP.COM (Paul Austgen) (07/27/90)
Does anyone have any schematics for a ciruit that would substitute for the flasher in automobile turn signals? It seems like a simple enough problem at first, but you would acutally have to sense current in the circuit that you were flashing off, I think. Thanks, Paul
v105l4lg@ubvmsd.cc.buffalo.edu (collie) (07/28/90)
In article <10960031@hpldola.HP.COM>, ppa@hpldola.HP.COM (Paul Austgen) writes. >Does anyone have any schematics for a ciruit that would >substitute for the flasher in automobile turn signals? It seems >like a simple enough problem at first, but you would acutally >have to sense current in the circuit that you were flashing off, > I think. >Thanks, Paul Hi Paul,you can use a timer (555) oscilating at some low frequency with the timer output driving a transistor,thus causing the bulb too flash at the frequency at which the timer is oscilating at. Then again you would have too regulate the input voltage for the little circuit,as the running engine and alternator puts out some nasty spikes enough too kill the timer (555). Then by turning on the power to the circuit will cause the light too blink on/off until you turn off the power switch. Good luck ! ******************************************************************************* collie ******************************************************************************* x
berryh@udel.edu (John Berryhill) (07/28/90)
Making the voltage regulator circuit for a 555 is a waste of time since you can get there with relays and capacitors. Better yet, just buy a flasher unit at an auto store. I LOVE the old GM flasher that passes the current through a nichrome wire wrapped around a bimetallic strip that bends upward and breaks contact. Then it cools back down and makes the contact again. Costs about 79 cents (or free if you take 'em out of the junkyard in your toolbox). -- John Berryhill 143 King William, Newark DE 19711
ppa@hpldola.HP.COM (Paul Austgen) (08/08/90)
Well, I agree that the bimetallic strip is the cheapest. However, the reason I asked the question is because on many newer cars, it takes a great deal of time and effort to even touch this flasher, and my experience has been that they can easily fail every couple of years. It can take an hour of hanging upside down under the wheel to even find it. I don't think just a lf oscillator solves the problem. You need a circuit to detect that current is flowing into the bulb. Otherwise, you would have to rewire the turn signal switches, which are normally buried in the steering column.