LEDs and PCB mounting

[Haberdasher]

Hi

I'm trying to order parts from smallbear for the Cupcake and Neutrino.  I'm a little confused about LEDs and the way that boards are mounted/situated inside a box.

LEDs:

What size do most people use, 3 or 5mm?  Does it matter what kind/brightness I get?  Are the resistors for the leds already part of the design or am i supposed to add them?

Board Mounting:

Are the boards just kind of suspended by the pots and LED/bezel, or do I need to order some standoffs?

hellllp 

[lincolnic]

I'm by no means an expert, but I'm pretty sure that 5 mm is the standard size. 3 mm LEDs tend to get used more for clipping diodes (anyone more experienced, feel free to correct me if I'm wrong). The resistors for the LEDs are part of the circuit, so you don't have to add anything extra. Get whatever colors make you happy.

As far as mounting, that's a matter of personal preference. If you're using PCB-mounted pots, then those will suspend the board once mounted in the enclosure. If you're not, the stiffness of the wires should hold the board in place. I use Small Bear's #24 pre-bond wire, and I know some of the other folks here do as well. They might have some more advice, too.

[Haberdasher]

Thanks for the info, linc!

So I guess when I get around to builing the krunkee I should use 3mm led's since the 2 red led's are listed as diodes?  Is that the way to go, or would 5mm's do just as well?

[madbean]

The stock Crunchbox uses 5mm for the LED clipping. I don't believe there is a difference in forward voltage between 5mm and 3mm for red diffused LED's, but I haven't checked to be sure. You should be able to fit either on the board, but the 3mm will be a little neater.

Also, most of the boards do have the CLR (current limiting resistor) and pads for the LED indicators. Not all, but most. This is simply for convenience. I find it very tedious to solder resistors to LED's so I avoid it when possible. And, of course, you can run wires from the LED pads on the boards and solder them to your LEDs to free up placement in your enclosure. you can mount them directly to the board, if you like, but they sometimes end up in awkward places on the boards.

For diffuse LEd's a 4k7 is standard for the CLR, and that's what is indicated in most of the projects. Hoever, for high brightness you can actually go much higher in value. I typically use wither 12k or 20k for high brightness types. You still get plenty of light, but the higher values will make your LEDs last longer.

[Haberdasher]

The stock Crunchbox uses 5mm for the LED clipping. I don't believe there is a difference in forward voltage between 5mm and 3mm for red diffused LED's, but I haven't checked to be sure. You should be able to fit either on the board, but the 3mm will be a little neater.

Also, most of the boards do have the CLR (current limiting resistor) and pads for the LED indicators. Not all, but most. This is simply for convenience. I find it very tedious to solder resistors to LED's so I avoid it when possible. And, of course, you can run wires from the LED pads on the boards and solder them to your LEDs to free up placement in your enclosure. you can mount them directly to the board, if you like, but they sometimes end up in awkward places on the boards.

For diffuse LEd's a 4k7 is standard for the CLR, and that's what is indicated in most of the projects. Hoever, for high brightness you can actually go much higher in value. I typically use wither 12k or 20k for high brightness types. You still get plenty of light, but the higher values will make your LEDs last longer.

Good info for a beginner like me who is trying to visualize what it all looks like in the box, thanks.  

I ordered the high brightness variety for my cupcake and neutrino projects.  To clarify things a bit further, does that mean I should change:

R12 in the cupcake &
R11 in the neutrino?

thanks

P.S. While we're on the diode subject, can I substitute 1n4004's for 1n4001's?

[madbean]

You can change the value if you find the LED's too bright with the stock value.  like bright LEDs, but not everyone does. I'd say bumping it up to 10k is a safe compromise.

Yes, you can sub 1n4004 for 1n4001 without any issue. Those are for polarity protection in those cases, and will not change the sound of the effect in any way.

[Haberdasher]

You can change the value if you find the LED's too bright with the stock value.  like bright LEDs, but not everyone does. I'd say bumping it up to 10k is a safe compromise.

Thanks.  I named the right resistors that would be changed in my previous post then, correct?

Yes, you can sub 1n4004 for 1n4001 without any issue. Those are for polarity protection in those cases, and will not change the sound of the effect in any way.

Cool, I have a lot of those.
What about in the Bloviator build where you call for a 1n4007?  Do I need to use that value or is 1n400x good there too?

[madbean]

Thanks.  I named the right resistors that would be changed in my previous post then, correct?

Yes.

What about in the Bloviator build where you call for a 1n4007?  Do I need to use that value or is 1n400x good there too?

Should be fine to use another type: 01, 02, 04, etc.

[Haberdasher]

The stock Crunchbox uses 5mm for the LED clipping. I don't believe there is a difference in forward voltage between 5mm and 3mm for red diffused LED's....

What about different diffused colors besides red?  Do they have differing forward voltages?
I have some 3mm diffused greens.  Should I stick with reds on the krunkee?

[Haberdasher]

Yay, another dumb questio.

I want to hook up an LED to one of your boards that doesn't have it built in.

I think I need to go from the tip of the dc jack -> resistor -> long leg of LED.?
Assuming that is correct where do I stick the short LED leg using the same 3dpt wiring schema that you provide for your other pedals?  Top left/1A??

thanks for the help!

[irmcdermott]

Yay, another dumb questio.

I want to hook up an LED to one of your boards that doesn't have it built in.

I think I need to go from the tip of the dc jack -> resistor -> long leg of LED.?
Assuming that is correct where do I stick the short LED leg using the same 3dpt wiring schema that you provide for your other pedals?  Top left/1A??

thanks for the help!

Hey man,

No such thing as a dumb question, that's why these forums exist.

Anyway, you're right. I always solder the resistor pretty close to the anode (longer leg) of the LED, than the wire to the other end of the resistor, then i throw some heat shrink over it all before I solder the wire to the DC Jack. Then the wire to the Cathode, put some heat shrink over it, then solder that to the top left lug of the switch.

Like I said, you had it right, just throwing in my two cents on the order I do it in.

[Haberdasher]

Thank you.  I appreciate the advice too!

[stecykmi]

The stock Crunchbox uses 5mm for the LED clipping. I don't believe there is a difference in forward voltage between 5mm and 3mm for red diffused LED's....

What about different diffused colors besides red?  Do they have differing forward voltages?
I have some 3mm diffused greens.  Should I stick with reds on the krunkee?

different leds will have different Vf. if you're using them for clipping purposes, it can make a difference, but if you're using them for an indicator, the difference isn't usually enough to bother changing limiting resistor values for.

in general, red led's have a lower value for Vf than most other types. they will clip a lower voltages than others. you can try looking up a datasheet for a similar led, it will give you a range of values for Vf. I believe your standard red led has a Vf value of 2.1V, while blue led's have Vf's in the 3.6v range.

[Haberdasher]

The stock Crunchbox uses 5mm for the LED clipping. I don't believe there is a difference in forward voltage between 5mm and 3mm for red diffused LED's....

What about different diffused colors besides red?  Do they have differing forward voltages?
I have some 3mm diffused greens.  Should I stick with reds on the krunkee?

different leds will have different Vf. if you're using them for clipping purposes, it can make a difference, but if you're using them for an indicator, the difference isn't usually enough to bother changing limiting resistor values for.

in general, red led's have a lower value for Vf than most other types. they will clip a lower voltages than others. you can try looking up a datasheet for a similar led, it will give you a range of values for Vf. I believe your standard red led has a Vf value of 2.1V, while blue led's have Vf's in the 3.6v range.

Aha, that's good to know.
I ended up using reds.
thanks!

[Haberdasher]

Yay, another dumb questio.

I want to hook up an LED to one of your boards that doesn't have it built in.

I think I need to go from the tip of the dc jack -> resistor -> long leg of LED.?
Assuming that is correct where do I stick the short LED leg using the same 3dpt wiring schema that you provide for your other pedals?  Top left/1A??

thanks for the help!

Hey man,

No such thing as a dumb question, that's why these forums exist.

Anyway, you're right. I always solder the resistor pretty close to the anode (longer leg) of the LED, than the wire to the other end of the resistor, then i throw some heat shrink over it all before I solder the wire to the DC Jack. Then the wire to the Cathode, put some heat shrink over it, then solder that to the top left lug of the switch.

Like I said, you had it right, just throwing in my two cents on the order I do it in.

OK, now.  What about a positive ground effect with no DC jack?  What do I do there?