Expert electric advise needed re speedo etc

[AhmedRSi]

Got a few questions; thought someone on CS must know about these specifics:

- Clio mk2 speedo - how does the needle turn? is it motor driven?
- is there such thing as a micro trip switch? Something that will change between circuits depending on the position of the needle?

Thanks.

 

[richy22]

No you cant put in colour change dials if thats what your asking!

 

[AhmedRSi]

Why not? anything is possible.

 

[James.f]

The speedo works from the ABS sensors, if that helps

 

[AhmedRSi]

Was discussing this with someone who has done it on other cars, but his approach is to mount 3 smds in a triangle under the needle so depending on the angle (and rpm) different colours could be done. Seems a easy way to do it but I was thinking of doing it so the whole dials changed colour not just the needle illumination the needles dont have their own illumination per se, they are just transparent and illuminate whatever the dials below do.

 

[richy22]

You would need to make some kind of circuit up that could determine where the needle was at any given time and light up a different led.

Not worth the hassle IMO.

 

[Dink]

you just need to find the speed pulse signal and find a controller that can convert the signal to one that is able to control a tri-colour led driver

this should be able to do something useful with the speed pulse

 

[AhmedRSi]

^can the signal not be taken from the loom?

Why do I need to do a tri-colour led driver? Why not just wire up two differend LED circuits (one blue... one red) and use two seperate signals from speed pulse in opposite polarities? (if that makes any sense)

 

[AhmedRSi]

Another idea. I could mount a micro switch to the circuit board so that when the needle passed over it (the part under the black cover ie not seen) it would hit the micro switch at a certain rpm (depending where the switch was located) then activate the other circuit (red)

 

[richy22]

Because it doesnt work like that.

 

[richy22]

Another idea. I could mount a micro switch to the circuit board so that when the needle passed over it (the part under the black cover ie not seen) it would hit the micro switch at a certain rpm (depending where the switch was located) then activate the other circuit (red)

An then you would need to shut off the other circuit too

 

[Dink]

you might be able to hook it up to one of these

set it up for dot mode and connect the one set of leds to outputs 1-5 and the other set to outputs 6-10

i'd say you could use any speed pulse just need to find out how to set it up

also a micro switch wont be that small tbh

 

[AhmedRSi]

Anyone got any ideas? Hooking it up to the speed pulse seems a bit more complicated tbh.... im tempted towards finding some sort of mechanical method...

 

[AhmedRSi]

I think i've just found something....http://www.youtube.com/watch?v=vwRtp3kVeuQ

 

[richy22]

There isn't a switch small enough I don't think, u must of seen how tight for space it is under there.

 

[Dink]

your not going to be able to do it with anything mechanical

also if you could you'd have to mount something on the front of the dials

 

[AhmedRSi]

Basically I've been in contact with the person who did this...

[youtube]hFVVjaZeCug&feature=fvw[/youtube]

Who did it all mechanically. He explained how to do it but i dont want just the needles.

Why would I have to mount something in front of the dials? the needle has a black cap where 1cm ish of the needle is hidden... perfect?

 

[AhmedRSi]

Edit... just had an idea. Why can't i do something simular to how heater controls work in a ph1? (various resistance rings attached to rotating face)...

 

[richy22]

Yes and that will be based on what me and dink were on about in that you'd need to build up a circuit that could do that.

 

[Dink]

the black cap covers the part of the needle that attches to the stepper motor so there is no space behind the black cap

unless of course you changed the black cap to something about 30mm in dia. to hide everything

also one other thing is i really don't know what the f**k i'm on about lol

 

[AhmedRSi]

^In which case I could just lie on the these on there side, attach something to the bottom of the needle to activate it?

But that would only switch one circuit on (red leds). How could I then switch the first circuit off? Maybe it would be an idea to just use bright red leds to give a dark red/purple tinge at high rpm.

 

[AhmedRSi]

Can this be used to activate two circuits?

 

[Dink]

you could use that switch as it is a spdt switch

but you could only use it at the very end of the needle movement probably the last 200rpm

 

[richy22]

F you really want to try the microswitxh route then find a microswitch that is a double pole, single through, normally closed.

I can show u a diagram tomorrow (on my phone at the mo) on how to wire it up so that when the switch is activated it turns one led off and turns the other on.

 

[AhmedRSi]

^thats limited because of the length of the lever yes? Just had the idea as well that the resistance from pressing this switch would maybe affect the accuracy of the rpm reading? (if it need significan resistance fromthe needle to move the fin)

What about the following? (applies to a shift light but I can just use that to turn on LEDS instead? http://foz11.tripod.com/DIY_MOD_s/Digital_Speedo/digital_speedo.html

 

[AhmedRSi]

I can show u a diagram tomorrow (on my phone at the mo) on how to wire it up so that when the switch is activated it turns one led off and turns the other on.

Thanks. I'm a beginner that really doesnt know much about electronics but am a keen learner!

 

[richy22]

^thats limited because of the length of the lever yes? Just had the idea as well that the resistance from pressing this switch would maybe affect the accuracy of the rpm reading? (if it need significan resistance fromthe needle to move the fin)

What about the following? (applies to a shift light but I can just use that to turn on LEDS instead? http://foz11.tripod.com/DIY_MOD_s/Digital_Speedo/digital_speedo.html

That's why a switch wouldn't work (well not that kind anyway) the needles in a phase 2, if you put them back in place too hard youl find they don't move freely, similar "might" happen if a switch like that is used.

 

[Dink]

it's not really the length of the lever is more that the switch will have to be fixed so once the needle hits it the needle will stop

the switch is right as it has a common and normally open and a normally closed contacts which swap when the swich operates

 

[AhmedRSi]

Ok think im gnna try to do this by using the signals from the rpm signal already in the cars wiring...

Page 8 bottom diagram. Would that work with the frequency>voltage thing that Dink recommended in the first few posts?

Also - does any of this make sense to you guys?

Anyone can feel free to argue this if they think it wont work...
what youll need:
Lowpass Filter (resistor and capacitor)
another capacitor (largue value, get something over 3000microfarads)
4 Diodes

assumin the pulse from the tach is strong enough to power your led, hook up a lowpass filter (simple RC circuit with cutoff freq 1/(2*pi*R*c). if you want the light to turn on at lets say, 4000RPM, and lets say the corresponding frequency is some kind of sine/square wave at 60Hz, then what youd want to do is setup that lowpass filter to cutoff at about 50Hz. then, you can use a bridge rectifier (google it, its pretty simple), its 4 diodes thatll reroute the negative part of the signal to be positive (itll give you the equivalent to the absolute value of a sine wave, all humps going positive).. .then, this new sine wave gets fed into the large capacitor... if all goes well, this capacitor should turn your signal to almost a constant DC voltage (assuming your wave is oscillating faster than the capacitor is discharging), which can light up your LED for the shift..

it wont be an on/off thing, but the closer you get to your shift point, the brighter it should get.. but this is assuming the pulse from the tach has a high enough voltage and can supply enough current

and no offense tobut i dont see the need for a 555 capacitor, since you already have a frequency from the ecu for the tach. zener diodes are cool but those inductors can be bulky.. i just dont see the need of such a complex circuit

 

[Dink]

if you look on the technical datasheet of both items it will give you a load of circuits you can make using the items

 

[richy22]

Yes it makes sense but that's a very arse about face way of doing it. And long winded.

Capacitors charging to light an led...f**k me that's old old school!

 

[AhmedRSi]

Ok scrap what that guy said then!

Whats the conclusion then? Whats the easiest way to use the RPM signal in the car to create a sequencial shift light (eg 1, then 2, then 3, then 4 leds lit up)

Do these help?

 

[richy22]

You can already buy a shift lighter me jiggy for a Clio I think, swear I've seen one.

 

[AhmedRSi]

Yeah they cost alot compared to diy... plus im not really interested in a shift light really; but will be using the same curcuit/principle to change the colour of my dials at certain rpm

 

[richy22]

Suppose I could break out the osciliscope and do some readings to see what actually happens with the rev counter at certain rpm.

It's obviously signal related you just need a circuit that can convert this signal into limghting LEDs.

That component dink gave you does that, haven't looked fully at the spec sheet mind.

 

[AhmedRSi]

Would awsomely appreciate any help mate!

Also having difficulty identifying which wire on the loom going to the clocks is for rpm on my ph1 lol...

 

[richy22]

I might even have a load of crap lying around at work that could be used...hmmmm finish work off quickly tomorrow and spend the rest of the day playing with circuits??? If I get a chance I might.

 

[richy22]

Would awsomely appreciate any help mate!

Also having difficulty identifying which wire on the loom going to the clocks is for rpm on my ph1 lol...

Have u got a haynes manual?? Should tell u what pin it is on the connector.

 

[AhmedRSi]

Left the haynes at home, but think i've found it from the other thread. Dont really want to hijack that other thread but you mentioned the signal may be affected? would leds really draw that much power away? even if they were ran in parralel to the clocks?

 

[richy22]

It's not to do with power of the LEDs as such.

That lm3914 pictured above has an input pin which in theory you would take pin 4 of the red connector too. Now "if" that chip fit whatever gets some kind oscilation through bad connecting up then that input pin "could" have some kind of positive or negative voltage drop/rise which would impact on the signal already there. This could cause tha signal to not to right therefore not working the clocks at all.

Power is kind of irrelavant as you will be powering the circuit from somewhere else and not that pin. Power is easy, interfeering with the rpm signal is bad.

If you can follow what I'm saying!