not so simple scr trigger help

[adown]

I bought new motorcycle mirrors with sequential turn signals built in. The problem is my flasher wont let them complete. Flasher is an electronic package with built in canceler. I would like to run my running lamp wires(no longer used) to the turn signals through an SCR triggered by the flasher circuit with a transistor in series with the SCR so when it senses nothing from the flasher it will in essence turn of the SCR. I know it will need an r/c circuit to keep the transistor conducting during the flasher off time, but I don't know what configuration the transistor should go and how to incorporate an r/c circuit or the flasher input into it. Any help will be greatly appreciated. Thanks, adown

 

[colin55]

I assume you want a feature where you press the left-turn button and the flasher keeps flashing.
When you want to turn the flasher off, you press the left-turn button again.

I designed a module for this and sell it for $35.00 to all motorcycle shops.

It is simply a "D" flip flop chip with buffers. The buffer drives a relay. The relay powers the flasher module.

Look on the web for "latching relay" I don't have the circuit available as a separate item.

 

[adown]

No, I'm looking for a scr trigger circuit that will turn on with a press of the turn signal switch and turn off when the auto canceler turns of the flasher. The trigger is easy. The turn signal switch is a momentary switch, but I want it to stay on until is senses no voltage on the trigger(flasher) wire then cut the voltage to the scr.

 

[colin55]

You can easily turn on an SCR but it's very difficult to turn it off.


That's why I produced the "Latching Relay" circuit.

 

[adown]

Yes, I thought about that, but my bike has a turn signal auto canceler and I know there is a way to do this. It's just going to take more know-how than I have. Thanks for your in put. I always welcome any and all suggestions.

 

[MrDEB]

using a 7555 timer

adjust R3 for desired time.
It will retrigger after desired time.
suggest the 2 second time, that way after you make your turn it will shut off because if it takes longer than 2 seconds to make your turm well??
I agree that an scr is too hard to turn off unless you want to spend the $35
the cmos version of the 555 is chosen as it will take up to 18v dc.
an automotive electrical system (read motorcycle) delivers from 12- 14v.
the small transistor can be a 2n2222, all it does is deliver a low signal to the 7555.
the tip will handle I believe 5amps.
You may need to change the base resistor value R5
the circuit should work IMHO

 

[adown]

Thanks Mr.Deb for your reply. It's not the $35.00, it's just not what I'm looking for. Is that just a timer circuit that out puts a voltage for a determined amount of time from a one shot pulse. I'm going to attach a drawing of what I had in mind. Keep in mind I have just enough training to make myself think I can do this, but I've also been known to try and re-write the laws of electronics.

 

[colin55]

Your circuit is all wrong, but that is beside the point.

We need to know how the canceller works. It is time-determined or does it detect something from the steering of the motor-bike?

 

[adown]

All wrong? It has everything I need. LOL This isn't the first time I've been told that. I believe the canceler works on the tipping motion of cornering. It is in plastic box that contains the whole turn signal apparatus. I thought about cutting in to it but I'm still under warranty and also can't readily get to it.

 

[colin55]

That's why I have sold thousands of Latching Relay modules.
Because all the other cancelling circuits are not reliable.

I am only going by the demand. I don't ride a bike.

No-one from any of the bike repair shops or mod-shops has mentioned there is any alternative.

 

[MrDEB]

yes its a one shot pulse BUT!

as long as the turn signal is flashing the timer stays running as the flasher is triggering the circuit.
As soon as the turn signal is cancelled the timer shuts of (thats why I suggest the 2 second time using the 200K / 10uf configuration.
the scr is really not the route to go with. to hard to turn off the scr.
My circuit does all that you want ????
goes from point A to point B but visits point C along the way.-LOL

 

[colin55]

Can you draw a complete circuit diagram showing how the flasher-unit is connected as a feedback to the 555, as well as the input from the left-turn signal and right-turn signal.

 

[MrDEB]

my circuit is an alternative

to a latching relay If I am deciphering this thread correctly.
How many thousands of my circuit will be sold to cycle shops now?
its a cheaper alternative than a relay. perhaps more reliable??

 

[Diver300]

I bought new motorcycle mirrors with sequential turn signals built in. The problem is my flasher wont let them complete. Flasher is an electronic package with built in canceler.

Are you saying that the "on" cycle on the existing flasher on the bike is too short for the sequence of lights on the mirrors?

What I think is happening is this:-
If you power the mirrors from a 12 v battery they flash each of their lights in sequence and then stop.

However, that takes longer than than the "on" cycle of the existing indicators on the bike. You are only getting the start of each of the flash sequence.

You want to provide power to the mirrors until they have finished their sequence.

Is this right?

If so, you could use a thyristor, one for each side of the bike. The circuit assumes that the sequence lights on the mirror stop taking current at the end of the sequence, and that they continually take current when changing from one light to the next. If either of those is wrong, you may need a different circuit.

Also, if you indicate right and then change to left, there is no way of stopping the right mirror finishing its sequence.

 

[MrDEB]

your pic is an SCR

I assume you mean a triac?
the circuit I posted will stop after desired time "on" I would think 2 seconds or less would be sufficient?
a triac can be used for DC.
problem I see is the mirror lights may dim the other lights. you have the lights in parallel. Might cause abnormal blinking??

 

[adown]

MrDeb, I'm sorry that is my misteak, the lights have a sequencer circuit in them, they are not in parallel. Dont get me wrong here, I might have to go with your timer circuit as it does what i need. I was hoping to do this without a pc board although it would be small.Diver300 If I connect 12v to the mirrors they sequence until disconnected. Yes the flasher doesn't let it complete the sequence. Does a triac turn of after the signal is gone? I've tried that exact circuit from Diver300, but once on it stays. Unless he meant a triac. Thank you, adown

 

[adown]

Thanks for all your help guy's. colin55, this is what you need to start making. The auto canceler comes on a lot of bikes now and forgetting to turn of your signal can cause an accident. There are a few auto cancelers on the market, but I couldn't find a thing on what people are doing for these sequential signals whether they're in mirrors or not. Thanks again for all your replies, adown

 

[colin55]

What is the principle of operation of the "sequential signals" you mention in your reply.

 

[adown]

I've seen basic sequential strings sold, but what I have are mirrors with 3 arrows that have sequencers built in them that light one after the other from inside to out until all 3 are lit for use as turn signals. Now that more and more motorcycle company's are using auto cancelers and electronic flasher systems you cant just jumper around the flasher for a steady signal. Some people might be ok with only 2 of the 3 signals lighting or having to turn on then turn off the signals. I on the other hand am willing to go the extra distance for proper working signals that work with the factory canceler. Even if it mean begging for help on the electro-tech forums. Thanks again, adown

 

[colin55]

All the electronics to produce the effect on the set of LEDs is within the flashing unit.
All the unit needs is a constant supply (for any duration) and the unit provides the "effect." The unit is no different to a flasher unit. It simply requires a voltage (and current).
That's why my Latching Relay unit operates all these types of turn indicators.

And possibly the other circuit described above will work as well. It's just the advantage of a Latching Relay or any type of latching circuit gives you the advantage of turning the unit off when you have completed your turn.
And this is what the cycle-mod-shops want. They want a "fool-proof" design.