Driver Circuit For 280Zx Dinger

[Captain Obvious]

But.... (before I forget again).

 

The self flashing xmas bulb would certainly be the easiest and simplest approach of all. So if you can get that to work, it'd be perfect. I'd explore that a little more before delving into other more elaborate means.

[TomoHawk]

The Miata dimmer too. 

[Captain Obvious]

I've not taken one from a Miata apart, but I suspect all of the knob dimmers from every manufacturer uses some sort of a PWM concept by this time. It's way cheaper to build something like that than to do it the brute force and ignorance method they used in our Z's.

 

Cheaper, smaller, lighter, more reliable, and more efficient since it doesn't burn up all that energy as heat. Nobody's going to use a big honkin' ceramic core pot anymore.

 

And speaking of such... Since the original Z "pot design" is already ground based controlled (low side), it should be a breeze to convert the Z over to one of the newer PWM controllers instead of the original pot design for the dash lights if you're so inclined. You would need to run one additional wire (hot at all times" to a controller and you're done. There are lots of the newer styles that have twist knobs instead of roller wheels.

[TomoHawk]

Well, at least one good thing came of this idea-  the ability to replace the dimmer rheostat with something better.

 

I think I would like that, if you could  build it so the potentiometer sticks through the lower dash, as it does (just glue on an extension rod.)

 

 

It's a shame that there isn't a company that can make new wiring harnesses, so we can incorporate all these improvements people are discovering-  brighter headlamps, digital EFI, dash light dimmer, and what else?

[TomoHawk]

Do you happen to know what the duty cycle, flashing patter, is for a blinking LED? It seems like 50% and 1Hz.  I suppose I will just have to go buy one.

[Captain Obvious]

Timely question as I was just looking at some datasheets yesterday, but the end result is that I think you're going to have to buy one.

 

I went looking for details because I was thinking about your idea of using the self blinking LED as a device to switch a transistor off-n-on and I was wondering if that would actually work. Problem is that I don't know how the self blinking LEDs work inside and I don't know what the current draw is through them when they are dark vs when they are lit.

 

It would make sense that the current draw through the device would be higher when the LED is lit, but I'm not sure if that's really the case. They may simply shunt the current around the emitter die when they want it dark (think "short across the LED die portion") and the overall current might not change that much. So, I went looking for some info on datasheets and it's extremely vague. I didn't spend a whole lot of time searching out datasheets, but the two I found give absolutely no data on current draw ON vs OFF.

 

Here's the two I turned up:

 

http://www.kingbrightusa.com/images/catalog/SPEC/WP36BHD.pdf

http://www.sunledusa.com/products/spec/XLUR50C.pdf

 

So there is some info on the blink rate, but there's no spec for duty cycle or current draw in the different states. Two pages on solder temp profile and lead bending though!

 

If you buy one and take some measurements, make sure you post your findings.
 

[TomoHawk]

It worked!  You're (I'm) a genius:  the blinky Christmas tree bulb idea.

 

Please view the attached videos.

 

Flashing light Only: 

 

 

Light with ding-dong:  

 

 

 

 

 

It's not exactly a 50/50, 70/30, or 80/20 cycle, but the objective was to get a pleasant ding-dong alarm to replace the annoying buzzer to warn you that the headlights are on.  This looks like it will work.  I just have to pt it all together nicely and swap it in for the buzzer.

[TomoHawk]

Here is a photo of the completed bulb-timer:

 

Photo 1:

 

I clipped the leads from a willing resistor ad formed a tint loop in the ends of each.  Then I used very fine sandpaper to clean the black coating (which prevented soldering) from the leads of the bulb. I made a little hook in the bolb leads and hooked them to the resistor wires, ad soldered.  then I bent the leads up s the new leads  went t the top of the bulb.  Then I got a short piece of heat-shrink tubing ad encapsulated  the whole mess, so the new leads stick out enough to solder wires to. Photo 2.

 

It still works!  I was afraid the think leads of the bulb would break off after soldering so that's why I covered it all wit the heat-shrink tube.

 

I tested the bulb again with the dinger to see if it had any kind of preferred "orientation."  It doesn't.  Just hook it up inline with either the +12V or Gnd wire of your dinger.

 

The dinger was listed on eBay as "HYUNDAI ACCENT BELL CHIME  96820-25100"  Oter models on eBay  has similar chimes.

[TomoHawk]

Here is a photo of the completed bulb-timer:

 

Photo 1:

 

I clipped the leads from an old resistor and formed a tiny loop in the ends of each.  Then I used very fine sandpaper to clean the black coating (which prevented soldering) from the leads of the bulb. I made a little hook in the bulb leads and hooked them to the resistor wires, and soldered.  Then I bent the leads up so the new leads  went to the top of the bulb.  Then I got a short piece of heat-shrink tubing ad encapsulated  the whole mess, so the new leads stick out enough to solder wires to. Photo 2.

 

It still works! 

 

I was afraid the thin leads of the bulb would break off after soldering so that's why I covered it all with the heat-shrink tube.  All I need to do now is to solder some short  wires to the leads that stick out, and a small connector (probably from the old buzzer.)

 

I tested the bulb again with the dinger to see if it had any kind of preferred "orientation."  It doesn't.  Just hook it up inline with either the +12V or Gnd wire of your dinger.

 

The dinger was listed on eBay as "HYUNDAI ACCENT BELL CHIME" Other models on eBay  have similar chimes.

[Captain Obvious]

That's awesome! I love the simplicity of the solution and I'm thrilled that the easiest solution actually worked! Of course, they usually don't,

 

The bulb is glowing a little brighter than I think it should, so you might burn it out sooner than it would in normal application, but unless you purposely leave your headlights on, it probably won't matter. And even if it does go south, it cost what... fifty cents?

 

If you find you're popping bulbs like gumdrops, then just use the flashy bulb to drive a transistor. Similar to what you drew for using the self-blinking LED to drive the transistor. You can use a resistor or two to adjust the current down a little and also to generate a base voltage for a transistor switch.

 

Just remember, that the dimmer it glows, the shorter the off cycle, and the longer the on cycle will be.

 

I love it when a plan comes together!

[TomoHawk]

That's where I got the leads from the resistor. I was trying a couple different values (1k, 470k ohms) to see if I could get the flashing to slow down, but neither had an effect, and the lamp didn't even light! (due to the black coating on the leads?)

 

The cost isn't the price of the  bulb;  it's really the hour I needed to solder on stronger leads, and probably another hour to  crawl under  the steering column to mount and plug it together. If a better, permanent thing comes along, I'll consider it.

 

In any case, The thing  is only there to alert you that the headlamps are on, which usually only happens occasionally instead of all the time, as well brake lamps illuminate. So I think the bulb should last a long time.

 

Any way, thanks for the educational discussion!   

[Captain Obvious]

You gotta remember that the filament resistance on a bulb like that is only going to be a couple Ohms, so if you put a 1K resistor in series with it, you'll drop 99.9% of the voltage across the resistor and the current will be throttled down way too low to glow the filament. If you want to cut the brightness I'd start looking at adding maybe an Ohm or two. It might not have been the black coating, It may very well have been the resistor. Academic at this point however.

 

So speaking of academic, how did they drive it in the original application? Was there another module that supplied the intermittent DC to the ding-dong?

 

I've mentioned before that Integras (my experience is with the earliest ones) used a ding-dong device for the headlight warning. I never looked at it... I wonder how they did it. I wonder if it's self contained with both driver and ding-dong.