DIY Warning Light Assimilator?

How many do you want to make? I have all kinds of these parts laying around my shop. Postage wouldn't be much. The LED's might be orange instead of red.

Dave
69S

DogT said:

How many do you want to make? I have all kinds of these parts laying around my shop. Postage wouldn't be much. The LED's might be orange instead of red.

Dave
69S

Click to expand...

Found the surplus place. If you've been in one you know what they are all like. :mrgreen:

Had to get the LM741 at Radio Shack.

I think I was out $6-7. If I mess up too many I might take you up on some of them. Let me see what I can do with this stuff.

Hello,

I built one from plans at http://web.archive.org/web/200108051956 ... ke/wla.htm (the original site has been taken down). It's been working for me for about six or seven years. When I first hooked it up, I didn't like it because the light comes on much more often than with the original WLA and I disconnected it for a year or so. After I broke down on a long trip due an alternator stator wire breaking, I decided to hook it back up.

For some reason the web archive doesn't have the schematic, the most important part.

I have a copy of the schematic at:


This one works off Voltage, and the light should come on when the voltage drops below approximately 12 Volts. With the engine idling, it will typically be off, but with the engine idling and the lights on, it will typically light up. After running with it for a while, you get to know when it should and shouldn't be on and I have found it to be a useful diagnostic tool. For example, I was out for a short ride and the warning light came on while I was cruising at 3500 rpm or so, so I rode straight home. When I got home discovered my original Lucas rectifier had finally died. Another time I was riding around a parking deck at work and realized that the warning light wasn't coming on like it normally did when I put on the brakes, sure enough my brake light was burned out. You can build this for less than ten bucks with stuff from Radio Shack.

About the only advantage the original warning light assimilator has over this is that it comes on as soon as the ignition is turned on, so you get a visual confirmation that the ignition is turned on. This circuit won't do that. I've felt pretty foolish a few times when I'd kick started my bike 2 or 3 times and then realized that I'd forgotten to turn on the ignition.

-Eric

So this is what I built. It worked for a few seconds until the LEDs burned out. I'm guessing I did something wrong...

swooshdave said:

So this is what I built. It worked for a few seconds until the LEDs burned out. I'm guessing I did something wrong...

Click to expand...

Yes, leave it to someone who knows what they are doing! or at least learn to solder properly(it doesn't take much more time to do it neatly and is easier to work out what you did wrong) I know you like to post loads of pictures but I think this is one you should have left :mrgreen:

Dave,

Did you run the adjustable resistor too far and burn out the transistor or led's? My test circuit is still working fine. Add a 5K resistor in series with the pot to keep from running the resistance all the way to 0 like Jean suggests.



Dave
69S

Hey Dave -

If you like playing electronics experimenter, I recommend that you get a prototyping board like this
http://www.newark.com/wisher/wb-104-3-j/bread-board-wb-104-3-j/dp/62M1028
You can plug wires into the contacts and play without soldering.

Once the circuit is working, I suggest mounting it to a perf board for durability (cut to needed size)
http://www.newark.com/vector-electronics-technology/169p44xxxp/pcb-prototyping-board/dp/38F411

Way better than taped up components.

I also recommend NOT using a variable resistor in the final build - they're very poor at handling vibration.

Which circuit did you choose?

JAYMAC said:

Yes, leave it to someone who knows what they are doing! or at least learn to solder properly(it doesn't take much more time to do it neatly and is easier to work out what you did wrong) I know you like to post loads of pictures but I think this is one you should have left :mrgreen:

Click to expand...

All I was doing is tacking the parts for a test. What don't you like about my soldering? :roll:

DogT said:

Dave,

Did you run the adjustable resistor too far and burn out the transistor or led's? My test circuit is still working fine. Add a 5K resistor in series with the pot to keep from running the resistance all the way to 0 like Jean suggests.

Dave
69S

Click to expand...

That's exactly what I did. Green LED is dead, Red is ok. Didn't put in the extra resistor to save it.

I may try the other circuit next. Nothing like an opportunity to burn out more components!

I thought about trying the 741 circuit, but didn't like the looks of it, plus it has a bunch more parts. I'm thinking that as the voltage goes down, it may not work like you think, you may need a fixed voltage to drive the 741 (read another battery). I kind of like this little circuit with the 2 lights, I may clean it up, replace the pot with some fixed resistors, pot it with some glass bedding epoxy for gun stocks and stick it somewhere unobtrusive, maybe near the ignition switch under the top of the panel where you can see it. I always like the KISS principle.

Dave
69S

WARNING LIGHT ASSIMILATOR
Lucas Type 3AW (1971 and later models)

This is an electro-mechanical device for ignition warning light control.

With the ignition switched on, the warning light is supplied with battery current; when the engine is started and the alternator output reaches 6 volts approximately, the contacts inside the unit open and break the warning light circuit, switching off the warning light.

Click to expand...

I take it we're talking 6v AC here?

Gday Swoosh, good onya mate for havin a go I say. Not costing much and having a bit of interesting fun on the way.
Foxy

Foxy said:

Gday Swoosh, good onya mate for havin a go I say. Not costing much and having a bit of interesting fun on the way.
Foxy

Click to expand...

Finally someone who gets it.

"Getting it" is one thing, paying for a new replacement and simply plugging it in is another!

grandpaul said:

"Getting it" is one thing, paying for a new replacement and simply plugging it in is another!

Click to expand...

Not an option with neg ground.

RGM sells a battery voltage indicator for small money that lights up the warning light when the battery voltage drops bellow 12 volts, It doesn't indicate charging in real time, but if your charging system isn't working the battery voltage will drop to below this in a minute or two and the light will come on, it sometimes comes on at low RPM with the headlight on but then goes out after a minute or two when the revs rise.

dave M said:

RGM sells a battery voltage indicator for small money that lights up the warning light when the battery voltage drops bellow 12 volts, It doesn't indicate charging in real time, but if your charging system isn't working the battery voltage will drop to below this in a minute or two and the light will come on, it sometimes comes on at low RPM with the headlight on but then goes out after a minute or two when the revs rise.

Click to expand...

SOLID STATE WARNING LIGHT CONTROL UNITS. THIS DEVISE SWITCHES A WARNING LIGHT OFF WHEN THE ALTERNATOR OUTPUT REACHES 12 1/2 VOLTS SUITABLE FOR ALL ALTERNATOR MACHINES

Click to expand...

Yes, that's something similar. $23/£ 15.40

Still isn't as fun as making it yourself. :mrgreen:

That's the one I'm using on the 72, Works great! And you still use the original lights in the bucket.

FWIW just hooked up a voltage monitor this week (learned of it here and it got a good review) and it would probably do what you need for $27 http://signaldynamics.com/index.php?pag ... &Itemid=77
Five states using three colors for various voltages and does give me a good idea how (and if) the charging system is working. Ended up rearranging my indicator lenses as I found the LED colors could be seen well through the amber lens (but not the green or red) , so used it and reassigned the red lens to the turn signals and installed the LED in the amber lens relocated to the center...works great and the bike still looks stock. Installation was very easy, removed the original charge indicator bulb and holder and plugged the monitor into the white switched power wire in the headlight shell and ground. One feature I especially like is that the LED dims after several seconds if it is in a steady state but goes back to full brightness if there is a change. Anyway, not quite a clone of the assimilator but does monitor the electrical system well and is cheap and easy to install...