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Jay2903 |
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Jay2903 Scooby Slapper
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WD Forte |
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WD Forte World Chat Champion
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Teflon-Mike |
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Teflon-Mike tl;dr
Joined: 01 Jun 2010 Karma :
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Posted: 00:54 - 18 May 2018 Post subject: |
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Telling us what bike, what speedo, may help.....
One idiot-lamp 'tell-tale'... common bit of electrickery, and yup.. does sound like it shouldn't work... but it duz.
You have a common feed from the flasher unit, going to the indy switch; indy switch points electric at indy lamps on one side or t'other, each is earthed, lamps flash.
To make the tell-tale work... it has NO earth. The bulb is coupled accross the out-puts of the direction switch.... electrick goes into switch, switch points it at that side indy-lamps, and the tell-tale... electric goes to indy lamps making them come on, but some goes through the tell-tale... comes out the tell-tale, and has to flow through the 'off' indicator lamps on the other side to get to earth... there's a 'law' a propper leccie can probably quote that relates the voltage through a 'node', but esentially, you put 12v on the input side of the tell-tale, and the resistance of that bulb makes the voltage on its other side drop.... so the volts that come out of that and might go through the normal indies on the 'off' side, isn't enough to make the bulbs light up, but there is continuity, so the electric can find its way back to earth... clear as mud?
Basicacally the 'bridge' tell-tale does work, with one bulb coupling both sides of the indicators, and dont light them all up.... PROVIDED... the indies DO have bulbs in them..... if you have LED's that have bog all resistance, then the enough volts that make it through the tell-tale may be enough to make them light up.... and you dont have an LED in the tell-tale... cos its a diode, so volts can pas one way, but not t'other, and the tell-tale will flash with one side indies but not the other depoending on whether the electrics flowing the way LED allows.
Your issue.... you have wiring with two tell-tale lamps, one in parallel to each side indies.... your speedo has one tell-tale and expects a bridgecircuit for the bulb in it, that you dont have.
Choices... either you make up a bridge circuit as the speedo is designed for.... or you try squeeze two bulbs into one hole...... which, isn't actually so difficult if you have a hole for a typical peanut bulb dash-lamp and a couple of component LED's you can wedge in the same hole with a bit of insulation tape or RTA. ____________________ My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?' |
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WD Forte |
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WD Forte World Chat Champion
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Jay2903 |
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Jay2903 Scooby Slapper
Joined: 03 May 2016 Karma :
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Posted: 01:57 - 19 May 2018 Post subject: |
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Teflon-Mike wrote: | Telling us what bike, what speedo, may help.....
One idiot-lamp 'tell-tale'... common bit of electrickery, and yup.. does sound like it shouldn't work... but it duz.
You have a common feed from the flasher unit, going to the indy switch; indy switch points electric at indy lamps on one side or t'other, each is earthed, lamps flash.
To make the tell-tale work... it has NO earth. The bulb is coupled accross the out-puts of the direction switch.... electrick goes into switch, switch points it at that side indy-lamps, and the tell-tale... electric goes to indy lamps making them come on, but some goes through the tell-tale... comes out the tell-tale, and has to flow through the 'off' indicator lamps on the other side to get to earth... there's a 'law' a propper leccie can probably quote that relates the voltage through a 'node', but esentially, you put 12v on the input side of the tell-tale, and the resistance of that bulb makes the voltage on its other side drop.... so the volts that come out of that and might go through the normal indies on the 'off' side, isn't enough to make the bulbs light up, but there is continuity, so the electric can find its way back to earth... clear as mud?
Basicacally the 'bridge' tell-tale does work, with one bulb coupling both sides of the indicators, and dont light them all up.... PROVIDED... the indies DO have bulbs in them..... if you have LED's that have bog all resistance, then the enough volts that make it through the tell-tale may be enough to make them light up.... and you dont have an LED in the tell-tale... cos its a diode, so volts can pas one way, but not t'other, and the tell-tale will flash with one side indies but not the other depoending on whether the electrics flowing the way LED allows.
Your issue.... you have wiring with two tell-tale lamps, one in parallel to each side indies.... your speedo has one tell-tale and expects a bridgecircuit for the bulb in it, that you dont have.
Choices... either you make up a bridge circuit as the speedo is designed for.... or you try squeeze two bulbs into one hole...... which, isn't actually so difficult if you have a hole for a typical peanut bulb dash-lamp and a couple of component LED's you can wedge in the same hole with a bit of insulation tape or RTA. |
Cheers for the help mate. The two bulbs one hole suggestion wouldn’t work in this case. What do you mean by bridge circuit ? |
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Jay2903 |
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Jay2903 Scooby Slapper
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Teflon-Mike |
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Teflon-Mike tl;dr
Joined: 01 Jun 2010 Karma :
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Posted: 11:25 - 19 May 2018 Post subject: |
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Bridge circuit, is easier to draw than explain.... but my botophucket is botophucked....
Left indy circuit
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Bulb
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Right Indy Circuit
When volts on left indy they flow through bulb making it light up.
When volts on Right indy circuit, they flow through bulb the other way, making it light up.
The volts find thier way through the bulb to earth on the side that's 'off', but because there's a voltage drop caused by the bulb in the middle, the volts that get through aren't enough to make the 'off' side indies light up..
Its an ingeniousely simple bit of wiring. Only needs one tell-tale lamp, and no diodes or anything, so its cheap and simple and rugged. ____________________ My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?' |
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WD Forte |
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WD Forte World Chat Champion
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WD Forte |
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Old Thread Alert!
The last post was made 5 years, 289 days ago. Instead of replying here, would creating a new thread be more useful? |
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