LED Dial Pointer for SX-434 (and others with grain of wheat?)

[two.dogs]

LED Dial Pointer for SX-434 and others with tiny grain of wheat bulbs

Now that my SX-434 is working, I wanted to re-lamp using all led. The grain-of-wheat lamp in the pointer was a problem until I realized I had an smd led that would fit. Part number is Cree CLM1C-WKW-CVBWB453. Dimensions are 3.2 mm x 2.7 mm. An smd works well because you can aim the emitter straight down the pointer. Most regular leds are too big. Even the smaller ones have to sit sideways in the housing so not much light gets into the pointer. First photo shows how I sandwiched the led between an old metal bracket and the tip of the wire (bent 90 degrees). I set my cutters on top of the wire to keep it in place. I really need to get once of those hand's free clamp things with a magnafying glass! I'd probably go a little less bright if custom ordering the led. This one has luminous intensity of 1600 mcd. Maybe it'll look less bright when I get the dial lit up.

 

[Watthour]

Nice mod. The pointer itself will make a nice reading lamp, even without the dial lamps.

 

[Marty Socal]

Maybe you could add an extra resistor into the bulb circuit to dim it a bit?

 

[two.dogs]

It really is a reading lamp! Way too bright. The light travels down the pointer, hits the beveled reflective surface at the tip, and shines a little spotlight on the inside of the dial glass, highlighting the dirt. I'd need to put in carbon-arc lights for the dial to even things out. I might try more resistance, but its already running on 15 miliamps instead of 20, so prolly wont go too much lower. Can't bear to disassemble the dang pointer assembly again, so I might be stuck.

However, I've got bragging rights now. My little SX-434 might be low on wattage, but my pointer light will absolutely blow the doors off of any SX-1280 out there. I should have titled the thread "Viagra for Pioneer Pointers".

 

[Watthour]

I like that attitude. "It may not have the watts, but its LUMENS spank your 1280 every day of the week and twice on Sundays..."

Perhaps you could add resistance upstream of the wires to avoid having to disturb the LED again? Obviously, you've got the positioning just about perfect.

 

[Marty Socal]

The graph in the data sheet looks like it might still run with 5 mA current (2.85V). If it's not too hard to change the resistance, it might be worth a try?

http://www.cree.com/led-components-... and Modules/HB/Data Sheets/CLM1CWKW(879).pdf

You also could call it the little Luke Skywalker SX-434 with his light sabre vs the Deathstar SX-1980! :lazer:

 

[two.dogs]

I'll add some resistance tonite and see how it goes. Osram make an led that looks like a good fit.

LW T67C-S2U1-5K8L-Z

Its got 560 mcd (vs 1600). Bonus is that its forward voltage is 4.1V (vs 3.2) so less power dissipated in the dropping resistor. I think I'll try this one on my SX-939. That receiver has enough wattage that it doesn't need to compensate with lumens.

 

[two.dogs]

OK, that looks better. Just so you know, I used a diode and 100uF cap to half-rectify the supply for the light circuit. Went from 8VAC to a measured 10.6VDC. I initially used a 680 ohm resistor in series with the led, but I've increased that to a measured 1350 ohms. Voltage drop across the resistance is 7.1V, so that gives 7.1/1350 = 5.3 miliamps, and the led seems to idle just fine. Thanks, Marty.

Of course, I'm losing my bragging rights. Maybe I'll mount a big toggle switch on the front to select super-turbo-pointer-mode just in case any SX-1280's stop by for a light sabre duel.