warning lamps for dashboard

Wiring, instruments, switchgear etc

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Re: warning lamps for dashboard

Postby Land Locked on Sun Oct 11, 2009 4:00 pm

Any time guys. Electrical was a bit of a specialty when I "swaaied spanner" for a living.

As an aside, I am more than happy to help out in person in exchange for drinks and help/advice with my own build. That said, I have no experience with toyota, ford or the aftermarket systems you guys are using, I can however read so if there is documentation available I should cope.

Regards
Johan
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Re: warning lamps for dashboard

Postby muller on Sun Oct 11, 2009 4:21 pm

I'll definitely remember that next time we battle. Electronics is a black art to me! :P
Anton

Race car 1: Birkin IRS 4AGE 20v (TLR class B - B10)
Race car 2: Birkin IRS 4AGE 20v (TLR Class B for SO - B20)
Road car: erm.. who cares
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Re: warning lamps for dashboard

Postby andredp on Sun Oct 11, 2009 4:48 pm

Nice diagram. I also run a LED, but without some of the circuitry in the diagram. Anyone able to tell me what the 1N4007 is for? I cannot see its function, and it would only act to drop the voltage supplied.
Andre'
Racing: Locost Racer - Rocam with plastic intake manifold ;)
Upgrading: Luego Locost SA - ex 4AGE 20V - soon to be x2 on KWs
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Re: warning lamps for dashboard

Postby muller on Sun Oct 11, 2009 5:46 pm

andredp wrote:Nice diagram. I also run a LED, but without some of the circuitry in the diagram. Anyone able to tell me what the 1N4007 is for? I cannot see its function, and it would only act to drop the voltage supplied.

Johan said I needed it and thats good enough for me!!! :wink:
Anton

Race car 1: Birkin IRS 4AGE 20v (TLR class B - B10)
Race car 2: Birkin IRS 4AGE 20v (TLR Class B for SO - B20)
Road car: erm.. who cares
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Re: warning lamps for dashboard

Postby Land Locked on Sun Oct 11, 2009 8:20 pm

Damn, I've been caught out. As I mentioned earlier I cribbed the idea off a VW Instrument cluster. I was in a hurry and not overly interested in why it worked only that it did in fact work. It was for use on a drilling rig going into deepest darkest Africa, so all that mattered was that it worked well AND reliably. In the years I was with VW and Audi we never had a charge light failure that was related to anything on the circuitry on the cluster. In my eyes that's a pretty reliable circuit.

Now as to some quick thoughts as to why we have a diode in the circuit.
1.The W or D+ terminal does put out a voltage when charging, so I think the diode is simply a blocking diode to prevent a backfeed.
2.LED's don't like reverse voltage. Reverse voltages as low as 5volts can cause them to self destruct.

Component values:
The 1n4007 can be almost any diode rated around 1 Amp.
The 820 Ohm resistor could be any quarter watt or bigger resistor between 680 and 1200 Ohms, it only prevents the LED from self destructing.
The 100 Ohm resistor could be anything from about 90 to 120 Ohms and at LEAST 5 watts (10 or 15 would be better), any lower on the wattage and heat becomes a HUGE issue. I have measured lower wattage resistors getting over 200 degree's Celcius.

Feel free to post any other questions, we all benefit from them.
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Re: warning lamps for dashboard

Postby andredp on Sun Oct 11, 2009 9:18 pm

mmm, Interresting thoughts

1. Ok yeah I can see that the diode may protect the circuit from high current should the high current charge lead on the alternator go toytoy.
2. Ah, of course, that sounds like a more plausable reason :) I like discussions like these 8)
Andre'
Racing: Locost Racer - Rocam with plastic intake manifold ;)
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Re: warning lamps for dashboard

Postby Land Locked on Mon Oct 12, 2009 7:50 am

Andre, I only have a little electronics knowledge. We all know that a little knowledge is dangerous, so I try to keep it simple and within my tiny limits.

With the above in mind I love these discussions too as they give a golden opportunity to learn.
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Re: warning lamps for dashboard

Postby ross on Mon Oct 12, 2009 9:16 am

I'm off to Comminca just now to see what they can offer.
Cheers,
Ross
Locost chassis with Toyota 20 valve blacktop and T50 box.
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Re: warning lamps for dashboard

Postby muller on Mon Oct 12, 2009 10:41 am

ross wrote:I'm off to Comminca just now to see what they can offer.
Cheers,
Ross

I walked into Roleen electronic and order the stuff on my list (from Johan), being a nood I asked are the diode's expensive, so the lady says, not really, 20c each! Felt like a numpty. The resistors were R2.5, add R5 for the LED so the whole setup cost less than R10!
Anton

Race car 1: Birkin IRS 4AGE 20v (TLR class B - B10)
Race car 2: Birkin IRS 4AGE 20v (TLR Class B for SO - B20)
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Re: warning lamps for dashboard

Postby ross on Mon Oct 12, 2009 10:55 am

Ok Just got back from Communica, where I chatted to a very helpful guy, whose brother is busy re building a Birkin. Got superbright leds, they didn't have all the colours available but I'm not really bothered about that. When I told the guy I wanted the lights for the dashboard he showed me these really cool led holders. They have a black bezel that is about 6mm high with an 8mm diameter lens mounted in the front, recessed by about 1.5mm. This gives a bigger light surface and also intensifies the light even more, very nice, I'm happy. I'd post pictures but I just can't get it right with photobucket.
Cheers,
Ross
Locost chassis with Toyota 20 valve blacktop and T50 box.
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Re: warning lamps for dashboard

Postby Van on Mon Oct 12, 2009 12:08 pm

ross wrote:I'd post pictures but I just can't get it right with photobucket.


Ross, which bit are you battling with? uploading them onto photobucket or putting them in the forum. Alternatively you can mail them to me (ettienne at landyonline dot co dot za) and i'll put them up as I am quite keen to see what they look like. :)
Ettienne

Building: Haynes Roadster -- 20V Silvertop -- T50
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Re: warning lamps for dashboard

Postby ross on Mon Oct 12, 2009 12:45 pm

Hi Ettienne,
It's a while since i tried but it was posting them that I had a problem with, my real problem is I just don't have patience for that sort of thing. I'll e mail you some pictures.
Ross
Locost chassis with Toyota 20 valve blacktop and T50 box.
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Re: warning lamps for dashboard

Postby ross on Tue Oct 13, 2009 12:01 pm

Hi Ettienne,
Sent you some pictures.
Ross
Locost chassis with Toyota 20 valve blacktop and T50 box.
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Re: warning lamps for dashboard

Postby Van on Tue Oct 13, 2009 3:59 pm

I did thanks Ross!

Image

Image
Ettienne

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