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Electronic flasher relay


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Hi Folks,

I have a Vehicle Wiring Products flasher relay (RFL5)

I am also using one of the audio buzzer units that Johnny 250 was producing a while ago.

The alarm works well but I have noticed that when the engine is running there is a faint glow from the alarm LED

I have changed the dropper resistor from 6K8 to 27K ohms but the faint glow still glows faintly

There is no faint glow when the ignition is on but no revs.

The flasher unit definitely clicks when operating but is desctibed as 'electronic'.

So what could be causing the faint glow !!!!!!

 

Roger

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That really depends on how you have it wired up Roger so I'm guessing a bit here as I'm not familiar with the technical spec of either the relay or the buzzer. I take it the audible buzzer is connected to the same terminal on the flasher relay as the tell-tale lamp and that by 'alarm led' that is what you mean?

That means the buzzer may be the source of the voltage and if its a passive electro-magenetic one it is just possible it is picking up ignition noise from somewhere and feeding that to the lamp. As it is a very small current already, increasing the dropper resistor isn't going to make much difference.

A simple check would be to disconnct the buzzer and see if the glow is still there. If it is, the source is the flasher relay itself.

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Hi Rob

the buzzer (12v) is in parallel with the LED& resistor.

The 12v come from the flasher warning light output.

I'll try your idea. I'll also connect to the buzzer to the line that goes to the flasher switch.

 

Roger

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Yes I did a forum search and found the video of him making it so I see what you have now Roger.  Its a piezo-electric buzzer so less likely to do what I guessed as there will be drive electronics inside it to generate the 'beep' frequency.  

Perhaps more likely then that it's something to do with the flasher relay itself. 

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I have noticed this on the flasher unit I recommend to people (& supply along with my own LED bulbs)

This effect is I think due to the fact that you have replaced the normal warning bulb with an LED type, which requires a lot less current to light up,

so much so, that even a few microamps will be enough to make it glow dimly. The wiring between the flasher unit & the bulb is most probably picking up a bit of induced AC voltage behind the dash (say from ammeter wires) this comes from the ripple on the alternator output voltage. (which is why it only does it when engine is running).

you could try putting a normal bulb back in, or just live with it (which is what I am doing !)

Bob.

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Hi Bob and Rob,

thanks for your input.

I suspect you are right about parasitic something or the other. 

Johnny250 doesn;t mention this with his design. I'm sure he used the original flasher unit.. But that shouldn't affect the parasitic situation.

Perhaps a poor quality LED may help rather than a Hi-brightness one.

 

Roger

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I wonder whether bridging the pins on the buzzer with a (say) 150 Ohm resistor  might help?  It  does mean the relay has to provide an extra 100mA or so, but the low impedance might stop the pickup. 

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Recently, I fitted a trafficator unit with click from Classic Car LED, and I have an old piezzo electric buzzer connected in parallel with the connection which feeds my dash lamp, which uses a conventional bulb.  The piezzo buzzer has been in place for years, and I have kept it because my car is very noisy and I can scarcely hear the click!  The benefit is that the electronic unit keeps a steady pace, even when running for a long time - the poor old bimetallic strip (original) flasher tended to become irregular when used for more than a few seconds.

I haven't noticed the bulb behaving oddly, either with engine running or not running.

When the engine is not running, I get a click, a buzz and a flash on the dash - as one would expect.

When driving, the piezzo tends to drown the click, and it (piezzo) does some double buzzes, which it did not do when used with the old (original) trafficator unit.  I have no idea why!

Ian Cornish

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There has been a lot of comments on the flasher especially with it being inaudible. Has anyone actually tried just extending the wires and moving it up behind the dash in front of the driver, maybe even mounting it on a  thin piece of stainless to amplify it?

Must admit I never bothered as I fitted a motorcycle buzzer that comes on after IiRC ten ‘flashes’ and resets itself if you touch the brakes.

Always struck me as an odd place to stick it.... down in the passenger (for us anyway) footwell surrounded by carpet and often sweaty feet!:blink: 

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Hi Roger,

If the LED is lighting due to parastic AC ripple as Bob suggests, and I think he is probably right, then it may help to include a 10uF (25Volt) capacitor across the LED,  and possibly a silicon diode (e.g. 1N4007), or suitable Zener diode, in series with the LED since that  increases the voltage required to light the LED. You may need to adjust the Resistor to get the ideal LED output.

Kind regards

Tony

Edited by tthomson
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  • 2 months later...

Hi Folks,

just to close this off.

I used  a separate wire from the flasher unit to the LED and it still glowed when not being used. So not parasitic

I have now made up another buzzer/LED unit and this time added a 10uF capacitor. 

The glow has gone.  HURRAY - Tony gets the cigar.

I suspect that the RFL5 flasher being electronic (plus a relay), has a leakage path from somewhere in it's bowls to the warning lamp out put.

Perhaps a 10uF cap in the flasher unit itself may be a better idea.

 

Roger

 

 

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Just had a look inside a RFL5 electronic flasher relay and the out put to the warning light has no damping capacitor etc.

This is OK for a filament bulb but causes the LED to twinkle when not flashing.

So tomorrow I shall install a 10uF cap inside the flasher and see what happens.

 

Roger

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15 hours ago, RogerH said:

Just had a look inside a RFL5 electronic flasher relay and the out put to the warning light has no damping capacitor etc.

This is OK for a filament bulb but causes the LED to twinkle when not flashing.

So tomorrow I shall install a 10uF cap inside the flasher and see what happens.

 

Roger

Is it being sold as suitable for LED`s ? If so a word with the supplier  perhaps wouldnt go amiss.

Stuart.

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1 minute ago, RogerH said:

Hi Stuart,

it does not state what it does or doesn't do

This is the one http://www.vehicle-wiring-products.eu/product.php/626/12-volt-4-pin-electronic-flasher-relay

If my fix this morning sorts it out then I'll contact the supplier. Although I'm not hopeful that they would be interested.

 

Roger

Seems you could do a customer review on it.............. Go on fill your boots!

Stuart.

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Looking at the description they would probably not be suitable for LED (exterior) bulbs.

I always recommend this one for filament, LED, or mixed use:

https://www.classiccarleds.co.uk/collections/indicator-relays-electronic/products/12v-electronic-indicator-flasher-relay-classic-car-with-oe-click-x-l-p-2-3-pin

 

Bob.

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1 hour ago, Lebro said:

Looking at the description they would probably not be suitable for LED (exterior) bulbs.

I always recommend this one for filament, LED, or mixed use:

https://www.classiccarleds.co.uk/collections/indicator-relays-electronic/products/12v-electronic-indicator-flasher-relay-classic-car-with-oe-click-x-l-p-2-3-pin

 

Bob.

Yes that one works well with LEDS and makes a ticking noise.

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2 hours ago, Lebro said:

Looking at the description they would probably not be suitable for LED (exterior) bulbs.

I always recommend this one for filament, LED, or mixed use:

https://www.classiccarleds.co.uk/collections/indicator-relays-electronic/products/12v-electronic-indicator-flasher-relay-classic-car-with-oe-click-x-l-p-2-3-pin

 

Bob.

Hi Bob,

      the only LED in the flasher system is the warning light with the buzzer all the outside lights are filament.

 

However we have success. Putting a 10uF Tantalum Cap across pins 31 (earth) and C (warning light) stops all the electrical noise and thus the background glow. - Hurray.

I have contacted Vehicle & wiring products (where I bought it) to inform them off the issue.

Perhaps one day I will change over to LED indicator bulbs. Should be interesting to see if the glow is present on them.

 

Roger

 

 

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1 hour ago, RogerH said:

Putting a 10uF Tantalum Cap across pins 31 (earth) and C (warning light)

Roger, you mentioned that the flasher "ticked". Do you think the output for the warning LED is a relay contact? If so I would advise against using a tantalum capacitor. The internal resistance (ESR) of tantalums is so small that they may not take the inrush current from a very low impedance supply via a a mechanical contact. If the inrush current doesn't do it, they don't like the "ringing" voltage that you can get in situations like this (exacerbated by that low ESR) so you should chose at least double the working voltage. It may not let go straight away, but when it does it can be spectacular (flames and smells) as they often fail short-circuit! I would normally suggest an aluminium electrolytic in a situation like this or a smaller value non-polarised type such as polyester. If you don't have one, you could perhaps add a small resistor in series with the 10uF - for example, 10R would limit the inrush to just over 1A and should snub any ringing.

Cheers, Richard

PS: Sorry to be such a Smart-Arse! :rolleyes:

PPS: I can't find a picture of a damaged tant, but I found this video. I've started at the aluminium electrolytic, but the tantalum is at 2:45

View here if embed doesn't work.

Edited by Spit_2.5PI
Failed embed Youtube video intelligence test.
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Hi Richard,

the electric noise that the Tant is damping is not going through the relay during the annoyance.

The flashing is via a relay but I do not know if the alarm light (LED) is controlled by the relay.

The LED does have a reasonable series resistor effectively inline with the Tant.

I'll give some serious tetsing and see how high the flames go.

 

Roger

Edited by RogerH
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