Can you help me re-connect my dip switch?

[AdrianRParticipant @adrianr18614]

Hi Tim,

I did not post this earlier as it does require the headlight switch to be able to carry the full dipped current. But if it can then this should do it without having a relay permanently on.

When the stalk is pulled or pushed RL1 turns on and powers the high beam, it also powers RL2 which disconnects the dipped.

 

P.S. I just noticed the ground and chassis symbols 😀

Edited By AdrianR on 17/11/2022 11:05:24

[Tim StevensParticipant @timstevens64731]

Adrian:

I think – on first glance – your version and mine are the same in practice.
The headlamps switch was designed by Joe Lucas, in about 1925, to work without any relay assistance, and sometimes had to feed a fog lamp or other extras as well. So, it is well able to do the business. And with a pair of LED 'bulbs' in the headlamps, the current is less than half what it was in the good old days. In fact, with headlamps and side lamps and brake lamps (twice as many of each type than when new) the current now is below the output of the dynamo. Progress indeed.

Thanks for your suggestions – Regards, Tim

[SillyOldDufferModerator @sillyoldduffer]

Posted by noel shelley on 17/11/2022 10:24:31:

Dave Flash now only works when the headlights are on, so no daylight flash ? Noel.

I hope not, because operating the Flash switch bypasses On/Off and the DIP/Main cluster, and connects the battery direct to the main beam. The relay also disconnects the Dip beam, but that has no power unless the headlights are ON.

Fingers crossed, I find it really hard to find mistakes in my own work, even bleeding obvious ones!

Dave

[noel shelleyParticipant @noelshelley55608]

Tim , To have a constant drain – even a small one will soon ruin a battery. I would take the green relay supply to the dip switch through the ignition switch to avoid a flat battery – or has it got a syntilla magneto ignition ? Noel.

[Tim StevensParticipant @timstevens64731]

Sorry, Noel – the constant drain is only constant while the car is running. Whenver I park the whole electric system is isolated by a big switch in the battery earth.

It did have a magneto (now carried as spare when on holiday) but I have converted a duff magneto to electronic coil ignition.

But thanks for saying what you did – I was careless with my 'constant'.

Regards, Tim

[AdrianRParticipant @adrianr18614]

Tim, the difference between our circuits is that the relays are only energised when the main beam is on, the rest of the time they are both off. So if you did forget to use your isolator your battery won't run flat due to the relay.

[Tim StevensParticipant @timstevens64731]

Adrian R :

How about this minor change to my version?

The lower relay is fed from the Green (always on) supply. Change this feed to Blue (headlamps on). Then it is only feeding the relay when the headlamps are on, and I'm not likely to leave the car parked in that state.

I think …

Regards, Tim

[John Doe 2Participant @johndoe2]

 

I have got it ! It is embarrassingly easy.

I am still away working so I hope my rough sketch is clear.

The feed "lights" obviously comes from a suitable fused battery supply.

The"IGN" feed is also fused and is fed from whichever IGN switch feed you want – I would use the accessory position. You need to ensure the IGN feed can supply the full current for the high beams.

 

Edited By John Doe 2 on 19/11/2022 11:33:03

[noel shelleyParticipant @noelshelley55608]

Many old cars, even in the 60s DID NOT fuse the headlights as BOTH lights are on the same circuit and a dlown fuse would leave you in darkness, possibly at speed and in a bend ! Modern cars fuse left and right seperatly, avoiding this problem ! One manufacturer, I think vauxhall used a divice that if excessive current was drawn would cause the lights to dim/ flicker but NOT go out, this was done by a thermal device Noel.

Edited By noel shelley on 19/11/2022 12:52:54

[John Doe 2Participant @johndoe2]

Fair point, and that seems reasonable.

The relay circuit is right though, the key being that both relays operate together – like a double pole relay – in this case achieved by simply paralleling both coils. The stalk either latches to select high beam when the light switch is on, or momentarily selects high beam flash even when the light switch is off. Whenever the high beams are on, the dipped beams are disabled

The two power feeds can come from wherever you feel comfortable, risk-wise. If the IGN switch cannot supply all the high beam current, feed only the high beam relay coil from the IGN switch but the actual high beam relay common terminal from a high current source. 

 

Edited By John Doe 2 on 19/11/2022 18:18:22

[Tim StevensParticipant @timstevens64731]

Thoughts about fused lights (etc):

First, any thought about current used by the headlamps is not going to help others (mainly) as I have fitted LED 'bulbs' throughout, and the headlamps now draw less than half that of a pair of H4 55W units.

Second, on this car the ignition switch (not fused) feeds only the ignition (and the start relay). One reason for doing this is that there are occasions when lights of some sort are useful but the ignition would not, and in particular, doing it this way simplifies the addition of hazard flashing. If anyone is interested in this option, it relies on a double-throw switch which joins the two sides of the flash output (left, and right), and links to a separate witness LED (which lights separately from the conventional warning 'bulb', in accordance with the law).

To stop the engine I turn off the ignition, and then when leaving the car, turn off and remove the lever of the 'FIA' switch which cuts the battery earth connection, and (separately) cuts the ignition feed. Apart from being a requirement of competition cars, this can serve to frustrate the light fingered chancer. Without such a two-layer switch, turning off the electrics in a 'panic' situation would not necessarily stop the engine, as the generator would be charging still. Overnight, the charger feed uses its own earth feed with a separate fuse tucked away.

A final oddity I have built in is that the main and dip circuits are separately fused, with a further, different fuse in the headlamp flash feed. So if either of the headlamp options (dip or main) fails, I can lift the lever to 'flash' and hope to see where I am going while I find somewhere to stop.

Hoping this helps someone else, too – thanks for all your interesting and helpful comments.

Regards, Tim

[John Doe 2Participant @johndoe2]

Back home from work now, so here is a slightly better diagram, showing the switches more clearly. Black dot = normally closed terminal, empty dot = normally open.

Each light has an individual fuse, so only one at a time would blow, leaving at least one other illuminated.

Both relay coils are de-powered when the dipped beams are selected: the relay coils are only powered when the high beams are selected.

The two lighting +VE supplies are up to you where you take them from.

I would take the flash control from the IGN accessory position – you might be waiting for your son/daughter/wife to emerge from where you are picking them up with your engine stopped, but listening to the radio.

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