DIY Warning Light Assimilator?

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swooshdave

swooshdave

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Even seen digital warning light assimilators for, what's the kind was of putting this, a bit of money. Some of them are pretty fancy and light up different colors for how much juice you're getting.

So how much would it cost just to make one work like the old one? I thought there was something in the INOA Tech Digest but I can't find mine. (I bet my brother has it...) and I think it was set up for + Ground, which doesn't work for everyone.

What I want is a LED that turns on when the voltage falls below a certain amount, right? Don't I really just want a light to show that the alternator is producing power? So run it to the battery and set it for 12v and if the battery isn't charging the light should come on or if the battery is too low. Maybe set it for 10v or what ever the Boyer likes so that if the LED is on you might want to kick the bike a few times before starting it?

Thoughts?

From the workshop manual:
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.

should the warning light fail to light when the ignition is switched on and with the engine stationary, disconnect the White/Brown lead from the "W L" terminal of the control unit and temporarily reconnect to the "E" terminal; if the bulb lights, this indicates that the control unit is faulty, but should the light still fail, then the bulb, connections, and associated wiring should be checked.
Click to expand...


I found these 12 Volt Battery Low Indicator LM741 plans for a battery low indicator for a 12 Volt battery using an LM741 operational amplifier which I think does just that. Looks like the components are simple and cheap. Prices are for Radio Shack, your locale may vary. You can also buy these parts off the interweb wherever you are.

DIY Warning Light Assimilator?

http://www.radioshack.com/product/index.jsp?productId=2062547

DIY Warning Light Assimilator?

http://www.radioshack.com/product/index.jsp?productId=2049726
I think I can use the 5.1v Zener Diode.

DIY Warning Light Assimilator?

http://www.radioshack.com/product/index.jsp?productId=2062302
I think this is the right "variable resistor".

And finally the resistor for the LED which you already have from the LEDs to replace the other indicator on your headlight bucket. :mrgreen:
DIY Warning Light Assimilator?

http://www.radioshack.com/product/index.jsp?productId=2062321

DIY Warning Light Assimilator?


Maybe $5?
 
swooshdave said:
So how much would it cost just to make one work like the old one? I thought there was something in the INOA Tech Digest but I can't find mine. (I bet my brother has it...) and I think it was set up for + Ground, which doesn't work for everyone.
Click to expand...
Dave, The schematic in the digest won't work. I built one 15 years ago, complained on the INOA list and an electrical engineering type looked it over and said it can't work. Then some others chimed in. Nobody has ever apparently built one that did.
 
Hehe, how about that, another feature in the official manual misleading us novices.
As much info as a simple on off lamp gives, just toot horn or flash high
beam and see how bright or dim they sound or light.
Also if bike sputters or stops on brake lamp lighting, likely low
or no battery not being pumped back up enough.

I and many others replaced Brog hive divice assimulator unit and indicator
by the Osborne color change LED meter. I got mine via
http://www.walridge.com/section/view/

hobot - Dave, stub axle should hit you next day or two.
 
What you need is a comparator. For example a LM339 is a quad (x4) comparator, and you can adjust the voltage that it will go off at. Not a big engineering problem. If you really want to do this let me know, but it will cost you big time. Otherwise you can read the spec sheets. National LM339 should get you there.

Dave
69S
 
DogT said:
What you need is a comparator. For example a LM339 is a quad (x4) comparator, and you can adjust the voltage that it will go off at. Not a big engineering problem. If you really want to do this let me know, but it will cost you big time. Otherwise you can read the spec sheets. National LM339 should get you there.

Dave
69S
Click to expand...

The only reason I was looking at the other one is that a diagram was provided. I could stare at the LM339 until I died and it wouldn't help.

So, if you think you can whip up a diagram I might take a crack at it. But I'll probably try the other one cuz I can just get the parts at Radio Shack. I might try yours another time.
 
If someone could figure the circuitry out that would be nice. I'd like to build one, but it's been years since I've done that sort of work. I write software for a living now. No more hardware design for me. You can probably find the circuit you need in one of the chip data sheets. They usually include example circuits, or at least they used to 30 years ago! It's not rocket science though, it's just a voltage comparator.

Debby
 
debby said:
It's not rocket science though, it's just a voltage comparator.

Debby
Click to expand...

Uh, huh. It's easy if you know what you're doing. Remember who you're talking about. :mrgreen:

I'm not afraid to make it with a recipe but I'm stuck without one.
 
You could do it with an LM3914 which is a bar/dot display driver, this way you could have a "range" of operation displayed, something like low voltage, correct voltage and over voltage. Take a look at the basic circuit at http://www.national.com/mpf/LM/LM3914.html This circuit http://www.reconnsworld.com/power_lm3914battmon.html would work, but it says it requires its own battery, so either making one like this http://cdselectronics.com/Kits/Battery_test.htm or buying a kit will do what you want and more. On your PR, if you do go with clipon bars, you can put the LEDs or the bar graph display and all the circuits in the little piece of handlebar that fits in the regular location on the triple trees.

Jean
 
I think you guys are missing a couple things here.

1) I am looking for something to replace the warning light in the headlight
2) and it has to be cheap and stupid, like me

So, given those perimeters, would the first device I presented work in a useful manner on a Norton?
 
I have the multicolored LED on 2 british bikes (Commando & Vincent) easy to plug: on the Commando I plugged it on the wire from the assimilator and grounded it. The only problem is the muliple colors not always visible. I have the simpler one, 3 colors, on a couple of old hondas with weak alternators and they are a lot easier to read. If I was able to find a "live" wire inside the Commando headlight shell, you should be able to do it to!
Philippe
 
debby said:
If someone could figure the circuitry out that would be nice. I'd like to build one, but it's been years since I've done that sort of work. I write software for a living now. No more hardware design for me. You can probably find the circuit you need in one of the chip data sheets. They usually include example circuits, or at least they used to 30 years ago! It's not rocket science though, it's just a voltage comparator.

Debby
Click to expand...

Hmm... so much in common. I'm an EE doing software too. And we ride Norton's. Cool.

Dave, I can cook up a couple of schematics for a simple comparator circuit. The complexity depends on whether you want a voltage monitor (simple) or battery charge indicator (more complicated). And positive or negative earth?
 
L.A.B. said:
http://www.nortonownersclub.org/support/technical-support-electrical/warning-light-assimilators
Click to expand...

Interesting.

DIY Warning Light Assimilator?


Unfortunately I don't know what the resistor values are in that circuit. Or what it would look like for Neg Ground.
 
Dave,
Here's a much simpler circuit. And it works, I tried it. Replace the 2 resisters, 10K and 47K with an adjustable of perhaps 12-15K. I used a 50K and it was all the way to one side at about 11K to make the red led come on at 12V. Use the variable to get the red one to come on at your desired voltage. Nearly any NPN transistor will work. Got it from http://www.4qdtec.com/batty.html

DIY Warning Light Assimilator?


Insulate everything and you can use it for positive or negative ground. If you don't want the green led, just hide it, it really doesn't tell you much except that there is at least about 5V present. Circuit draws about 25ma at 13V and goes down with decreasing V.

Dave
69S
 
Bear with me as I decipher the diagram:

Vcc = Voltage in? Bring this from the battery + ?

470R = 470 ohm resistor?
10K and 47K (also resistors but you recommend a variable one) Is the 100K-Ohm Horizontal-Style Trimmer on the other page the same thing?
3K3 - 3.3K Resistor ?

The thing in the middle is the transistor.

Will this one work?
DIY Warning Light Assimilator?

http://www.radioshack.com/product/index.jsp?productId=2062609 Not sure what rating to worry about. Is a power dissipation of 350mW and I(C) Max. of 200mA enough?

Which leg goes where? (Nevermind, I think Google answered this)

And lastly you ground the circuit out the bottom, where the logo is?

What I might do it is put the Green LED by the battery and run the Red LED to the Warning Light in the Headlight. Then to check the battery's condition you just look for the Green LED. And if the Red LED doesn't go out then you assume the battery isn't being charged.

Sorry for all the questions, I don't do hardware and I just tell people what to do to make the software. :mrgreen:
 
Yes, you pretty much have it.

470R is 470 ohms

10K and 47K are 10,000 and 47,000 ohms respectively, but use a variable to replace both of them. They are acting like a single resistor the way they are hooked up. Maybe to get a specific resistance they wanted. The resistance you want there is around 11,000, use a 12,000 to 15,000 ohm variable resistor and you can set the voltage that the red light comes on at what you want around 12V. Just use the center tap and one end for the variable, you don't need to use the 3rd lead.

3K3 is a 3.3K ohm resistor

The transistor you are looking at will work just fine. Looking at the flat side of the transistor with the legs down, the emiter (arrow) is the left one, the base (single lead going straight to the right) is in the middle, and the collector ( the wire going up at an angle to the left) is the right lead.

Vcc wire is at the top WHICH IS POSITIVE. The bottom wire which is not marked but going off to the right is NEGATIVE. If you have positive ground, hook the Vcc connection to ground and the bottom wire to your negative battery terminal or switched -V. Just flip it around if you have negative ground.

If you look inside the led, you can see one of the wires goes to a usually larger pointed gizmo, this is usually the negative side of the led.

Here is my test circuit, plus on the right minus on the left.

DIY Warning Light Assimilator?


You could probably build this with your red led remote and just pot all these items after you solder them together and bring out the plus and minus leads. You could bring out the leads for a remote green one if you liked too. You can make these leads as short as you like as long as they don't touch each other except where they are supposed to.

I checked the resistance of the variable R vs. voltage that the red led comes on, in my circuit, for 10V=8.4K ohms, 11V=9.2K, 12V=10.2K, and 13V 11.3K. Your circuit may vary because of the led's and the transistor. You could use a 20 or 50K variable, but a 15K would be easier to adjust.

Dave
69S
 
10K and 47K in parallel is equal to an 8.2K resistor. As mentionned, a trimpot would work just as good, but instead of only one trimpot, put a trimpot of 10K and insert a 5K resistor in series with it, if you don't do that and your pot is at 0, the transistor will pop. A 2N2222 ( http://www.stanford.edu/class/ee133/dat ... 2n2222.pdf ) would be quite OK in this circuit.

Jean
 
If you think I got giddy just to make an LED light up you can imagine what will happen if I get something this exotic to work. Luckily this is a family show so I'll spare you. :mrgreen:

Off to the electronics store.

http://www.cascadesurplus.com/
 
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