It doesn't work yet. Something to do with the transistor I used (BC857AT). No idea why it doesn't work though. Seems like it should. The LEDs light if I bypass the transistor though.

I have not asked Brian yet about making his boards or posting the design. I thought he was hard to get a hold of, but I will try.

Stu

Should work with that transistor. It's the same as I have used, except mine was a BC857A, not AT. Don't know what that T means, though...

Stig

This is what happens. The button LEDs are off when the player first comes on, but the knob LEDs are on dimmly. Then the button LEDs turn on to the proper brightness and the knob LEDs remain on, but dim. The brightness adjustments don't change the brightness of the knob LEDs, until turned to MAX. At this point, the knob LEDs essentially turn off, but the button LEDs become very bright, as expected. Setting the brightness to off turns the button LEDs off, but leaves the knob LEDs on in the same dim state.

I guess the transistor is the wrong kind or something. I tried two of them and neither one works. I'll try the one JRFAUST reccomended and see what happens.

Stu

Something to do with the transistor I used (BC857AT).

Ic for the BC857AT is only 100mA, for the BC857A it is 500mA, perhaps you are pulling too much current and killing the AT's?

Pdf datasheet's: BC857AT BC857A

Ah, didn't realize there was a difference. Maybe that's it. It bogs down under the load; it clearly isn't dead. I'm going to try a different transistor. Shucks, there goes $.12!

Stu

Strange. The datasheet I have for the BC857A says 100mA, but that is for a Philips transistor. And my board dims as it should...

Stig

Mm... in this application, just about any transistor of correct polarity should at least behave near to "normal", though possibly dimmer or brighter than the proper one. Have you verified correct polarity (PNP,NPN,whatever) ?

In reply to:

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Have you verified correct polarity (PNP,NPN,whatever) ?

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Yes, it's PNP, which is what I need, as far as I can tell.

Stu

Got the board, got the parts, soldered and installed it. Works great, looks great! Thanks, Stig!

For the record:

The LED's on Lopan's current parts list are the large ones from Brian's first board, the large one with 3 LEDs. For me, this was a good thing, because I ordered just one of those LEDs and so it matched the three I had already. And I was able to squeak them, barely, onto the board and make them work.

However, if you're doing one of the new knob boards and putting the LEDs on it from scratch, you should go down to the next smaller size. From looking at Brian's page, he also uses a smaller size than what I used.

The big ones I had worked, but they were super tricky to make fit. I even had to cut away a portion of one of the contact pads on one of the LEDs to prevent it from grounding against a different trace..

Lopan, you might want to update the parts list so it has both sets of numbers.

For someone who has never tried this before. What would you say the chance of success is for someone willing to try it but has never done a lot of electronics fabrication before?

I have been waiting for over a year like most of us and have just about given up hope of getting anything from Brian.

I am ready to try something on my own if I need to.

What would you say the chance of success is for someone willing to try it but has never done a lot of electronics fabrication before?

The hard part is the soldering. The components are really tiny. I dunno about making the sub-board, I haven't had to make one yet.

Take a look at Brian's instruction pages (the "buttons" link at the top of this page). He's got detailed photos of each step of the procedure. Also read my review of when I did one of the earliest kits.

Lopan, you might want to update the parts list so it has both sets of numbers.

Does anyone have the other LED part number handy?

I finally had a chance to try another transistor. This one was a through hole PNP from Radio Shack. This time the board worked as it should. Now I know that my original choice of transistor (BC857AT) was at fault, although I don't know why. I think the Radio Shack one is too big to fit, so I will try the MMBT3906DICT-ND from Digikey. I assume that will do it since several of you have reported success with it.

Bottom line, don't use the BC857AT; it doesn't work.

Stu

This is for anyone who might want to help those of us who have been waiting for a led button hack for a YEAR!

If anyone with the tech knowhow would like to make boards/buttons available I'd gladly buy from them. Waiting more than 365 days for a product is a little ridiculous

I can make the boards and offer parts. The one I made for my Empeg works now that I have a better transistor in there.

The design will have to be different from Brian's since he hasn't replied to my e-mail on the subject, but it will still have 4 LEDs and use the same parts. If humidity is a problem with the casting, I don't want to even consider trying it here in southern Louisiana, but the knob boards I can do no problem. I would like to have them produced at a board house, rather than etched in the shop here.

How soon do you need them? I can take a breather on some of my other projects and draw up the design and get it out very soon.

Board houses usually have a setup fee that's pretty steep, so I will need enough business to pay for that at the very least.

Stu

I would also have a board as well (complete or bare).

Also if you could supply the button leds as well.

C.

So that's 2 people that would be interested so far.

Stu

i would need 3-4 knob boards with leds for the buttons. Maybe more.

Cool, so that's 5-6+ boards.

Stu

Stu,

I'd be interested in four boards.

I don't need parts.

Thanks,

i'd take one plus parts if the price isn't ludicrous

One plus parts for me too.

Question:

Any reason to stop at 4 LEDs? Maybe 6? Maybe 8? Physical space is the only limitation, and I know that people have wanted to try and diffuse the light a bit better. Maybe more, smaller LEDs? If you are redesigning the board anyway...

Current drain.

And 4 LEDs with some diffusion material (photos posted somewhere) looks really really nice.

But heck.. even ONE LED with no daughterboard actually looks just fine.

Cheers

That's what I was thinking, but what is the limit in that respect? Does there necessarily need to be more light output or just a more evenly distributed light source? Perhaps using 150 ohm current limiting resistors and 6 LEDs or 200 ohms and 8 LEDs?

Stu

I never really thought about more than 4 LEDs. I guess I was always satisfied with 4. Anyone else think the new one should have more than 4?

I might be able to fit 6, not sure about 8. There really aren't that many white SMD LEDs from which to choose. I think the smallest ones available are already being used in Brian's 4 LED board.

Stu

Depending upon the price i'd take either one or two boards plus bits...

I'll take one board plus parts.

If 8 is possible. Why not?

I am in for two plus bits if the price is reasonable.
-Mike