car blinker circuit?

J

Jordan

Guest
I need to put a turn indicator blinker system on my 6 Volt vehicle.
I'm looking for a circuit to provide the timed flashing, maybe using a
555 IC.
Thought there'd be lots to find, but no. Any reason a 555 can't be used?
Anyone know of a suitable circuit?
I want to avoid electro-mechanical flasher cans.

Thanks
Jordan
 
"Jordan" <jwprincic@optusnet.com.au> wrote in message
news:4394d6e5$0$18203$afc38c87@news.optusnet.com.au...
I need to put a turn indicator blinker system on my 6 Volt vehicle.
I'm looking for a circuit to provide the timed flashing, maybe using a
555 IC.
Thought there'd be lots to find, but no. Any reason a 555 can't be used?
Anyone know of a suitable circuit?
I want to avoid electro-mechanical flasher cans.

Thanks
Jordan
Click to expand...
No circuits? Are you kidding? Search for '555 astable' and if you want to
narrow it down more add '50%' to the search terms. Use the output of the
astable to drive a MOSFET or relay to drive the lights.

Cheers.

Ken
 
"The Real Andy" <will_get_back_to_you_on_This@> wrote in message
news:3niap15i6iho3p50kqujttfb07v73d1po8@4ax.com...
On Tue, 6 Dec 2005 16:37:23 +1000, "Dand" <dand@dand.net.au> wrote:

There are simple ways, if you know electronics.

An inverter with a resistor across the input and output and a
capacitor from
ground to input will oscillate at the output as long as the inverter
has
some hysstatsis. If you use 2 resisters and a transistor as the
inverter
(pnp emitter ground, two resistors to source from the collector,
output
between the resistors, it should work ok.

Of you could just get a 555..... google it and you should hit about 10
billion 555 circuits
I need to put a turn indicator blinker system on my 6 Volt vehicle.
I'm looking for a circuit to provide the timed flashing, maybe using
a 555
IC.
Thought there'd be lots to find, but no. Any reason a 555 can't be
used?
Anyone know of a suitable circuit?
I want to avoid electro-mechanical flasher cans.


There is a 555 variant specifically targetet at automotive use, cant
remember it off the top of my head, but it exists. Personally, if I
were you, i would head down to my local supercheap (or similar auto
store) and by a generic electronic flasher. It will more that likely
work and if it doesn't it wont be hard to modify. I would be surprised
if you could not find one targeted for 6V.

BTW, what is wrong with a electro-mech flasher? They have been in use
for a very long time, and still are. They must have something going
for them.
Click to expand...
The thing they have going for them is that they flash at the legally
required rate 60-120 flashes per minute and they change rate when a lamp
fails (also legally required) indicating to the observant driver that
something is amiss.

You will need a 6 volt version because as you already know the current
is double for the same light output on 6volt systems. Incandescent lamps
should be 18 - 21 watts.
--
John G

Wot's Your Real Problem?
 
The Real Andy wrote:
There is a 555 variant specifically targetet at automotive use, cant
remember it off the top of my head, but it exists. Personally, if I
were you, i would head down to my local supercheap (or similar auto
store) and by a generic electronic flasher. It will more that likely
work and if it doesn't it wont be hard to modify. I would be surprised
if you could not find one targeted for 6V.

BTW, what is wrong with a electro-mech flasher? They have been in use
for a very long time, and still are. They must have something going
for them.
Click to expand...
I've looked, but not found any 6V electronic flasher cans.
The standard type of can probably won't be happy to drive LED bulbs,
which I want to use, as 6V bulbs are only available to 10 watt, which is
marginal I think.
And, while blinker cans tend to go bung every coupla years, I thought an
electronic solution might last a lot longer.
And, I want to be ready when all 6 volt stuff is no longer available.

Thanks
Jordan
 
On 2005-12-06, Jordan <jwprincic@optusnet.com.au> wrote:
I need to put a turn indicator blinker system on my 6 Volt vehicle.
I'm looking for a circuit to provide the timed flashing, maybe using a
555 IC.
Thought there'd be lots to find, but no. Any reason a 555 can't be used?
Click to expand...
the 555 may not be suited to the wiring layout.

most indicator flashers connect in series with the switch and only start
when the bulbs are connected. doing that with a 555 may not be so easy.

also possilby there's a cheaper solution, but for a one off
a 555 is plenty cheap enough.

Anyone know of a suitable circuit?
Click to expand...
what's the exact aplication (what loads, how is the switch organised)...

I want to avoid electro-mechanical flasher cans.
Click to expand...
what about electro-thermal :)

Are relays no good either?

Bye.
Jasen
 
Jasen Betts wrote:
the 555 may not be suited to the wiring layout.

most indicator flashers connect in series with the switch and only start
when the bulbs are connected. doing that with a 555 may not be so easy.
Click to expand...
I think I've got part of the solution: Use two 555's (or a 556) so that
each is energised by the blinker switch, for either left or right.
Means some unconventional wiring, but that doesn't matter in this case.
Vehicle has no key - ignition is by magneto. So having the blinker
arranged this way saves introducing a switch, which I'd be likely to
forget to turn off.

Cheers
Jordan
 
Jordan wrote:
Ken Taylor wrote:


You *could* have the 555 powered all the time, but why not use the
switch to apply power to the 555 and the relay/MOSFET/lamps? I don't
see the problem.


Yes, that's what I've figured out, using the blinker switch, but need to
use two 555's unless someone shows me how to do it with one.
The only problem is that I'm no electronics whiz!

Thanks
Jordan
Click to expand...
Well, I just tried to do some quick ASCII art and it looked crap, so
each to his own. :)

If you have a 'normal' blinker switch, it'll send either the 6V or the
ground to the appropriate side of the blinker unit, which then powers
the lamps.

For your application, you could use the same switch and use the 6V or
gnd to power the 555 circuit and one of the MOSFET's, which would
complete the circuit for one set of lamps only. Look at using diodes to
power the 555 and only one of the MOSFET's at a time.

Damn, that made bugger all sense to me too - can anyone do a quick bit
of ASCII???

Cheers.

Ken
 
Ken Taylor wrote:
For your application, you could use the same switch and use the 6V or
gnd to power the 555 circuit and one of the MOSFET's, which would
complete the circuit for one set of lamps only. Look at using diodes to
power the 555 and only one of the MOSFET's at a time.
Click to expand...
I understand that, thanks. Will see if I can come up with something.
Cost of parts is trivial, but keeping it compact and simple would be good.

Jordan
 
On 2005-12-06, Jordan <jwprincic@optusnet.com.au> wrote:
Ken Taylor wrote:

No circuits? Are you kidding? Search for '555 astable' and if you want to
narrow it down more add '50%' to the search terms. Use the output of the
astable to drive a MOSFET or relay to drive the lights.

Is it OK to have the 555 powered up all the time?
I'd prefer if it only got power when the blinker switch is activated.
It's refinements like this that I was hoping to find.
Click to expand...
They don't use much power I don't see a problem there, connecting it to the
ignition switch (or the indicator fuse) would probably be better than direct
to the battery.

getting the blink-rate feature could be harder.

Bye.
Jasen
 
"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:mf7cp1lj03uasj96lrdog1td30d9opvurn@4ax.com...
On Tue, 6 Dec 2005 20:19:23 +1100, "John G" <Greentest@ozemail.com.au
put finger to keyboard and composed:


"The Real Andy" <will_get_back_to_you_on_This@> wrote in message
news:3niap15i6iho3p50kqujttfb07v73d1po8@4ax.com...
On Tue, 6 Dec 2005 16:37:23 +1000, "Dand" <dand@dand.net.au> wrote:

There are simple ways, if you know electronics.

An inverter with a resistor across the input and output and a
capacitor from
ground to input will oscillate at the output as long as the inverter
has
some hysstatsis. If you use 2 resisters and a transistor as the
inverter
(pnp emitter ground, two resistors to source from the collector,
output
between the resistors, it should work ok.

Of you could just get a 555..... google it and you should hit about
10
billion 555 circuits
I need to put a turn indicator blinker system on my 6 Volt vehicle.
I'm looking for a circuit to provide the timed flashing, maybe
using
a 555
IC.
Thought there'd be lots to find, but no. Any reason a 555 can't be
used?
Anyone know of a suitable circuit?
I want to avoid electro-mechanical flasher cans.


There is a 555 variant specifically targetet at automotive use, cant
remember it off the top of my head, but it exists. Personally, if I
were you, i would head down to my local supercheap (or similar auto
store) and by a generic electronic flasher. It will more that likely
work and if it doesn't it wont be hard to modify. I would be
surprised
if you could not find one targeted for 6V.

BTW, what is wrong with a electro-mech flasher? They have been in
use
for a very long time, and still are. They must have something going
for them.

The thing they have going for them is that they flash at the legally
required rate 60-120 flashes per minute and they change rate when a
lamp
fails (also legally required) indicating to the observant driver that
something is amiss.

You will need a 6 volt version because as you already know the current
is double for the same light output on 6volt systems. Incandescent
lamps
should be 18 - 21 watts.

IIRC the flasher is also required to turn on as soon as the indicator
switch is activated. If so, then you can't just switch the output of a
free running oscillator.

-- Franc Zabkar
Click to expand...
Thermal flashers passed the current thru the heater wire and the lamp
until the wire was slack enough to let the contact close and short the
heater which lit the lamp and allowed the heater to cool and pull the
contact open, heat again etc etc. They were very critical of lamp
wattage and contact and ground cleanliness.

6 volt versions were even more critical.

Recent electronic flasher flash first and then go dark.

As far as I know all switches work on the hot side because almost
invariably the lamp holder was metal and screwed to the body and hence
grounded.
--
John G

Wot's Your Real Problem?
 
"Jasen Betts" <jasen@free.net.nospam.nz> wrote in message
news:5d72.43966e01.92b6e@clunker.homenet...
On 2005-12-06, Ken Taylor <ken123@xxxxtra.co.nz> wrote:
Jordan wrote:


Ken Taylor wrote:


No circuits? Are you kidding? Search for '555 astable' and if you want
to
narrow it down more add '50%' to the search terms. Use the output of
the
astable to drive a MOSFET or relay to drive the lights.


Is it OK to have the 555 powered up all the time?
I'd prefer if it only got power when the blinker switch is activated.
It's refinements like this that I was hoping to find.

Thanks
Jordan

You *could* have the 555 powered all the time, but why not use the
switch to apply power to the 555 and the relay/MOSFET/lamps? I don't see
the problem.

a typical indicator switch is spdt centre off.
that's the problem

--

Bye.
Jasen
Click to expand...
And just why is that a problem?? Centre off - bravo. Switch to 'left' and
power the 555 via a diode and the left 'relay' (or MOSFET, whatever); switch
to 'right' and via another diode to the 555 and the relay. Biggus Dealus.

Cheers.

Ken
 
Jasen Betts wrote:
On 2005-12-06, Jordan <jwprincic@optusnet.com.au> wrote:

Jasen Betts wrote:

the 555 may not be suited to the wiring layout.

most indicator flashers connect in series with the switch and only start
when the bulbs are connected. doing that with a 555 may not be so easy.


I think I've got part of the solution: Use two 555's (or a 556) so that
each is energised by the blinker switch, for either left or right.
Means some unconventional wiring, but that doesn't matter in this case.
Vehicle has no key - ignition is by magneto. So having the blinker
arranged this way saves introducing a switch, which I'd be likely to
forget to turn off.


you can't power up half a 556. making it work with a single chip (and
single mosfet etc) would make it more compact

a 555 might be the wrong solution.

an oscilator based around op-amps could sense the dark resistance and vary
the blink rate OTOH if he's using LED globes (or panels) they're not going


to fail suddenly. because each panel has multiple LEDs in parallel. so
variable blink rate isn't needed


hmmm, this one's compatible with standard wiring
and will only run when the lamps are switched on


+-------------+---------------------------+-->from
| | /| | indicator
| +---------(----[100K]-o< |--------+ | fuse
| | | \| | |
| | . . . .|. . . . | |
| | . VCC(8) . | |
| | . . | |
+---(---RES(4) OUT(3)-------------||--)---+
| . 555 . || |
+---TH(6) DIS(7)-- || |
| . . ||--+--->to switch
+---TR(2) CV(5)-- p-channel and lamps
| . . mosfet
--- . GND(1) .
10u~T~ . . . .|. . . .
| |
+---------+
|
----
////

the inverter could be made from the second half of a 556 etc...

the only problem is it starts off dark and iights up a short
time after the switch is turned on


this modification will have it light up immediately when it
turned on and then start blinking.

------+----
|
/|----(----------+
---------[100K]-o<1| | |
\|----(-------+ |
. . . . . | | |
. | | |
. | | |
OUT(3)------||----+ | |
. ||pch o-|--+----- left signal
. || |
. ||---o------ |
|
indicator o-+-------- right signal
switch

the Nor gate could be done with a couple of diodes, a pull-down
resistor and half a 556.


Bye.
Jasen
Click to expand...
Thanks Jasen, that's all interesting but I'm scratching my head a bit.
Can you please explain the use of the inverter? Does the circuit "sleep"
until the blinker switch is activated?
Also, how is a 555 (or half a 556) configured to act as an inverter?
I'm slightly more conversant with 555's than with op-amps etc, which is
the reason I'm using those.
What suggestion is there for a mosfet? I'm using what's at hand here -
some MTP3055V's, but these are I think overkill and only show 2.4V
instead of the 6V supply voltage. Would a smaller mosfet be likely to
saturate and supply the full voltage?

Jordan
 
On Tue, 6 Dec 2005 20:19:23 +1100, "John G" <Greentest@ozemail.com.au>
wrote:

"The Real Andy" <will_get_back_to_you_on_This@> wrote in message
news:3niap15i6iho3p50kqujttfb07v73d1po8@4ax.com...
On Tue, 6 Dec 2005 16:37:23 +1000, "Dand" <dand@dand.net.au> wrote:

There are simple ways, if you know electronics.

An inverter with a resistor across the input and output and a
capacitor from
ground to input will oscillate at the output as long as the inverter
has
some hysstatsis. If you use 2 resisters and a transistor as the
inverter
(pnp emitter ground, two resistors to source from the collector,
output
between the resistors, it should work ok.

Of you could just get a 555..... google it and you should hit about 10
billion 555 circuits
I need to put a turn indicator blinker system on my 6 Volt vehicle.
I'm looking for a circuit to provide the timed flashing, maybe using
a 555
IC.
Thought there'd be lots to find, but no. Any reason a 555 can't be
used?
Anyone know of a suitable circuit?
I want to avoid electro-mechanical flasher cans.


There is a 555 variant specifically targetet at automotive use, cant
remember it off the top of my head, but it exists. Personally, if I
were you, i would head down to my local supercheap (or similar auto
store) and by a generic electronic flasher. It will more that likely
work and if it doesn't it wont be hard to modify. I would be surprised
if you could not find one targeted for 6V.

BTW, what is wrong with a electro-mech flasher? They have been in use
for a very long time, and still are. They must have something going
for them.

The thing they have going for them is that they flash at the legally
required rate 60-120 flashes per minute and they change rate when a lamp
fails (also legally required) indicating to the observant driver that
something is amiss.

You will need a 6 volt version because as you already know the current
is double for the same light output on 6volt systems. Incandescent lamps
should be 18 - 21 watts.
Click to expand...

If you cant figure out a 555, then perhaps you should go with the
local auto shop's 6 volt electro-mech version of flasher.
 
IIRC the OP wanted a circuit that allowed him to have one flasher, but
couldn't work out how to do this - the answer is simple in that he just
needs to wire the flasher switch from the batt + to one side of each
flasher light pair (assuming + earth) and insert the flasher unit from a
point that connects all the earth side of the lights to an earth point - ie
it goes in the common earth return or the indicator lights.

The above approach also allows for the emergency ALL FLASHING situation by
using an EMERGENCY switch that applies + to both pairs of flashers

And this is assuming he can overcome the difficulty posed by John, if that
is still the case after converting to LEDs

David

John G wrote:

As far as I know all switches work on the hot side because almost
invariably the lamp holder was metal and screwed to the body and hence
grounded.
--
John G

Wot's Your Real Problem?
Click to expand...
 
On 2005-12-07, Ken Taylor <ken@home.nz> wrote:
"Jasen Betts" <jasen@free.net.nospam.nz> wrote in message
news:5d72.43966e01.92b6e@clunker.homenet...
On 2005-12-06, Ken Taylor <ken123@xxxxtra.co.nz> wrote:
Jordan wrote:


Ken Taylor wrote:


No circuits? Are you kidding? Search for '555 astable' and if you want
to
narrow it down more add '50%' to the search terms. Use the output of
the
astable to drive a MOSFET or relay to drive the lights.


Is it OK to have the 555 powered up all the time?
I'd prefer if it only got power when the blinker switch is activated.
It's refinements like this that I was hoping to find.

Thanks
Jordan

You *could* have the 555 powered all the time, but why not use the
switch to apply power to the 555 and the relay/MOSFET/lamps? I don't see
the problem.

a typical indicator switch is spdt centre off.
that's the problem

And just why is that a problem?? Centre off - bravo. Switch to 'left' and
power the 555 via a diode and the left 'relay' (or MOSFET, whatever); switch
to 'right' and via another diode to the 555 and the relay. Biggus Dealus.
Click to expand...
ok. I see now.

--

Bye.
Jasen
 
Franc Zabkar wrote:
IIRC the flasher is also required to turn on as soon as the indicator
switch is activated.
Click to expand...
Have you got a reference for that? Because as noted, the
electro-mech ones don't generally do it. I know the one
in my car doesn't, and I'd like to fix that without having
to build my own. If flashers are now required to do it,
I'd have a reason to get a refund on one that didn't :).

The other problem with most 555 circuits (and the inverter
circuit mentioned) is that the first half-cycle takes
noticeably longer. A flasher circuit shouldn't do that.
Any clever ideas about how to design this behaviour? Apart
from the obvious one of using dividers etc...

Clifford Heath.
 
On 2005-12-08, Franc Zabkar <fzabkar@iinternode.on.net> wrote:
On Thu, 08 Dec 2005 09:43:30 +1100, Clifford Heath
no.spam@please.net> put finger to keyboard and composed:

Franc Zabkar wrote:
IIRC the flasher is also required to turn on as soon as the indicator
switch is activated.

Have you got a reference for that? Because as noted, the
electro-mech ones don't generally do it.

The mechanical flashers require that lamp current flows through a
bimetallic strip which opens after it heats up. The electrical contact
is re-established after the strip cools down. If no current flows at
switch on, then what heats the bimetallic strip?
Click to expand...
The lasr mechanical flasher I looked inside operatd by a heater that
heats a wire that's stretched across a spring steel gasket. When the
wire stretches a little the gasket clicks into a new configuration that
closes the contacts and short-circuits the heater element.

I do remeber seing one bimetalic flasher,
IIRC it was a bekelite affair and had a heating element wrapped around
the bimetallic strip. I think the heated-wire versions are cheaper to
make.

Bye.
Jasen
 
On 2005-12-09, Jordan <jwprincic@optusnet.com.au> wrote:
Jasen Betts wrote:

I made something which is running well on the bench.
I'm using diodes to select which of two transistors will be powered up,
along with the 555, from the blinker switch wired to supply power.
I'm bringing out 2 wires to provide a visual indicator that it's
flashing - an LED in series from pin 3. It's a bit of a spaghetti
junction, with 7 wires coming from my flasher unit:

1. input left
2. input right
3. indicator in (to dash LED)
4. indicator out
5. output left
6. output right
7. earth

Comments:

- There's a small delay, but not as long as it takes to give a hand signal.
Click to expand...
that can be fixed by connecting the timing capacitor to the VCC pin instead
of to ground. a diode from ground to the timing pins might be a good idea too
in case this capacitor configuration is outside of

|
|
+-/\/\-----------(---------+
| | |
| +---------+ |
| | | |
| || | . . . .|. . . . |
+--||--+ . VCC(8) . |
| || | . . |
| +---RES(4) OUT(3)---+---
| . 555 .
+------+---TH(6) DIS(7)--
| . .
+---TR(2) CV(5)--
| . .
| . GND(1) .
| . . . .|. . . .
| |
| |
+---|<----+
|
|

initially-low astable

as you may have guessed I have the 555 outline in text file and just
import it and doodle the lines using the keyboard.












- No lamp failure feature, which would be nice but at least there are no
filaments.
Click to expand...



- Wiring is not conventional. I'd like to try the suggestion using the
inverter, if that makes it more like "standard".

Thanks to all for your help
Jordan
Click to expand...

--

Bye.
Jasen
 
Thanks Franc. I got an electronic flasher unit at a local
car bits shop, it was no problem at all, unlike last time
I tried some years ago. The guy knew exactly what I wanted.
 
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