Lighted Knobs

[SonicVI]

Now these would look cool on a pedal. Instead of an LED have status knobs. I emailed the seller about how they're powered and haven't heard back after at least a few days though. I would think they just have an LED inside them, but I don't know how they get power. They're a little pricey too.

http://cgi.ebay.com/Lighted-Knobs-for-Radios-Channel-Knob-Blue_W0QQitemZ5793435858QQcategoryZ48696QQrdZ1QQcmdZViewItem


Daniel

[tommy.genes]

I think that would be cool, but it would get expensive for anything more than a one-knob box.

Do let us know what, if anything, you hear from the seller.

-- T.G. --

[SonicVI]

I got a response today:

"Yes they could be used on other items, they power from 12 volt power, they are a universal knob with a piece of heat shrink that goes behind it and you shrink it to allow the knob to fit smaller shafts. There is two wires, hot and ground that you wire to power  "

Not sure if it'd be worth the trouble for a pedal.


Daniel

[tommy.genes]

I just went ahead and bought one. I'll post pics if I get it to work.

The main problem I see is the need for a 12V supply. I suspect there is a resistor that could be swapped out to make it work with 9V, but I hope it isn't permanently embedded in the plastic knob.

You could spend up to $3.30 for a knob, LED and bezel from Smallbear, and these cost $7.25. So you end up paying about $4 to add a unique feature to your pedal (at least until everyone starts doing it).

I think it would definitely become cost-prohibitive for multiple knobs (not to mention a big power drain), and I'm not sure how it would look having only one knob out of a set light up.

-- T. G. --

[SonicVI]

Definitely let us (or at least me:) how it works out when you get it.  


Daniel

[tommy.genes]

Well I received the knob today. Interesting little product.

There is a quite small donut-shaped PC board that has five teeny-tiny components on it (three LEDs and two resistors) and two wires coming out of it. This piece is designed to slide over the threaded part of the pot and is held in place with a piece of heat-shrink tubing. That way, the LEDs or their associated wires don't actually have to turn. The shaft and clear plastic knob turn above them and are illuminated from below.

Because the resistors are so tiny, they'd be virtually impossible to modify for a DIY-er, but fortunately I tested it with a 9-volt battery and they were still quite bright. (This piece was originally designed for 12 VDC mobile radios.) With the size and the diffusing property of the plastic knob, you'd have no problem seeing this thing glowing at your feet.

The only other concern (other than the price at $7.50 ea plus shipping) is current draw. I didn't measure it myself, but the instructions say this thing can draw up to 45 mA. You probably wouldn't want it on a battery-only pedal.

I'll post pics when I can, but that probably won't be before Weds evening at the earliest.

-- T. G. --

[Hal]

is it smaller than 0603 SMT?  While small, these are possible to mod, with a steady hand and a good soldering iron.  Or just put a resistor in series with the battery.

[tommy.genes]

is it smaller than 0603 SMT?  While small, these are possible to mod, with a steady hand and a good soldering iron.  Or just put a resistor in series with the battery.

Yeah that looks about right for the size of the LED, and the resistors are even smaller.

Since this piece was designed for 12 VDC applications, I was afraid it would not be bright enough at 9 VDC, but it is. Putting another resistor in series would make it even less bright, so no modification is necessary.

BTW, wouldn't you need a tweezer iron to remove/replace SMT components?

-- T. G. --

[dr]

....back in the old days (....) I came up with a way to light up the knobs on my pedals-paint the tops and indicators with Day-Glo fluorescent paint (like on the old hippie posters) and hook up a blacklight bulb over the pedal box (with a light cover-IMPORTANT!) they lit up and I could see them fine.Also, to keep from bending over and breaking my back-I put a little rubber cup on the end of a long dowel to tweak the pots........

[Hal]

BTW, wouldn't you need a tweezer iron to remove/replace SMT components?

-- T. G. --

need isn't the right word.  Yes, that would be the right tool for the job.  But SMT isn't _that_ hard to work with, as long as everything is tinned already.  Take a broken CDROM drive or somthing - anything in a modern computer, and play around with soldering and desoldering components.  It sometimes helps to have another tool to move the stuff around with.  I prefer a small screwdriver.  v

[tommy.genes]

Pics:




-- T. G. --

[tommy.genes]

Take a broken CDROM drive or somthing - anything in a modern computer, and play around with soldering and desoldering components.

Thanks, I'll give that a try. Working with SMT components would be a good skill to have in the toolbox.

-- T. G. --

[tommy.genes]

One more note...

The knobs seem to be designed for a 1/4" knurled shaft. I had to ream it out with a 1/4" bit to get it even close to fitting a 1/4" smooth shaft.

-- T. G. --

[petemoore]

http://www.marubeni-sunnyvale.com/uv_lamp.html
 Looks like they are doing some LED ultraviolet word here.
 backlighting might look cool. Be interesting to find out if you could get more than a modest glow.

[SaBer]

BTW, wouldn't you need a tweezer iron to remove/replace SMT components?

-- T. G. --

need isn't the right word.  Yes, that would be the right tool for the job.  But SMT isn't _that_ hard to work with, as long as everything is tinned already.

I agree.
Soldering SMT with a regular iron needs its own technique:
1. Melt a small blob of solder on one side.
2. Pick up the component with tweezers.
3. Melt that blob of solder, and push the component to its place.
4. Let it cool.
5. Solder the other side(s).