Dynamo LED Driver Circuit - PCB available

[Martin]

The dynamo LED driver circuit that has been discussed in this thread has matured and a PCB is available to help those who'd like to build it.
The following power curves have been achieved with a hub dynamo and this driver:


This is the circuit:


The hardware looks like this (ecaps C1..C5 are located off the board):


and it fits into a 1 1/8" steerer tube (C1..C4 went into the tube first, C5 resides inside the headlamp assembly):


The PCB is single-sided, FR4, intended to be hand-assembled, 100% thru-hole components (zero SMD).


All parts are standard and the key components are LM2907 analog IC and IRFD024 / IRFD9024 HEXFETs.
The source files of the design are here. Contains BOMs for both hub and bottle type dynamo application.

I'm going to have some of these PCBs made and want to ask around who would like some.
Please post in this thread how many you like, if you plan to use them for hub or bottle type dynamo, how many LEDs you plan to connect, what country you want them shipped to.
I estimate one of the PCBs will cost no more than EUR 5 (w/o components and assembly) plus a bit for shipping, but not sure abt the exact cost right now.
Update: Cost of my current stock is EUR 3.80 per PCB, plus shipping by letter. If you like one of these PCBs, please PM me.

[znomit]

Woohoo, just in time for summer.

Znomit / New Zealand
1x 3-LED hub

[PhxCycler]

This is awesome Martin! Thank you for all your work.

I'd like:
1 - 3 LED hub
1 - 6 LED hub

-Mike
Phoenix, Arizona

[Eddy]

Wow! There are a lot of good decisions in that circuit board!

I would like:

1 3 LED hub Shimano
1 4 LED hub Shimano
1 6 LED hub Shimano
+ 1 spare
So a total of 4 boards.

Thank you again.

Eddy

[bbaker22]

excellent!

1 - 3 led shimano hub

bbaker22

[Martin]

If desired, the circuit can as well be run with 5, 7 or 8 LEDs, while I haven't calculated the component values and tested it for these configurations.

The reason why I ask for your intended configuration while it's the same PCB for all:
With 6 LEDs (and more), the limiting parameter is the MOSFETs Vgs limit (20V). If a lot of people run 6 LEDs, I consider adding two resistors to gain some safety margin with this parameter.

[thomas.hood]

thomas.hood/ UK
1x 3-LED hub

Many thanks for all you work on this.

Tom

[dom]

Hi Martin
SON Hub
Shimano Hub
2 X 3
2 X 4
2 X 5
2 X 6
2 X 8

Top job mate

Cheers
Dom

[tspoon]

Sorry I was struggling with system problems for a few days. Put me down for 1 x 3 Led version. I live in New Zealand. Cheers Martin.

edit: hub version

[allan6344]

This looks like a good place to start:

1 - 3 LED hub
1 - 4 LED hub
1 - 6 LED hub


Thanks
Allan / US

[RidingUphill]

Great Work Martin!!! Just what i need.

1 x 3 LED hub
1 x 6 LED hub

Thanks,
James / Australia

[drgannet]

2 (probably 4 LED), please
Schmidt hub

Thank you

Martin (UK)

[Rogers]

Hi Martin

I would be interested in:
1 x 3 led off a bottle type dynamo

I am from South Africa.

Many thanks
Roger

[Kwijybow]

Hi Martin,

I'd be interested in a 1 x 3 LED, from hub.

Nelson Ralls,
Plano, TX
US.

[Eamon]

Thank you Martin.
Unless you plan to do this again sometime, I ought to get a couple against future need (and capability).

Three seems about right, all three for a hub dynamo.
2 SON and 1 Shimano, if it matters.
All will be either 3 or 6 LED's.

Thanks again,
Eamon
Seattle,Wa
US.

[Martin]

Meanwhile I have done a small redesign of the PCB. The changes to v2.1 are:

• Two additional resistors have been added to the gates of Q1/Q2 to form a voltage divider

In v2.0, Vsg of Q1/Q2 was close to the max rating when using 6 LEDs. The additional resistors allow the use of up to 8 LEDs. In the course of adding these parts, all resistors have been renamed / renumbered.

• The width of the track at the anode of T1 has been increased
  
  In v2.0 it burned when T1 fired repeatedly

• Capacitor C12 (gate of T1) has been removed
  
  The part was not necessary and has been removed

• Adjustable resistor R15 has been moved
  
  R15 (previously R13) has been moved slightly so it doesn't touch neighboring components
• A couple of cosmetic changes

In spite of the changes, the dimensions of the PCB remain the same. One part was removed and two parts were added to the BOM.

The link to the design source files (first post) now links this new design. You will need this, it contains the BOM and the asy guide.

----------------------------------

Be aware of a slight change of plan:
Initially I planned to have the plating-through process done though the boards are single-sided only. It was meant to better hold the components on the PCB and to avoid that traces get torn off. With my current supplier, this process would nearly double the cost of the boards, same cost as dual-layer. Since the boards I have so far populated show very good mechanical strength with kinked component legs, I decided I could get away without the plating through.
The copper traces of the PCB are 100% HAL solder-coated and the kinked ends of the component legs solder to the traces along their full length, this is what makes it strong.

----------------------------------

This morning I have ordered 5 sqdm of the new boards. The resulting number of boards will probably cover the qty so far requested. It will take 1 to 2 weeks for them to arrive here. I'll build one to be sure that the redesigned PCB is OK, the rest will be sent out until my stock is depleted.
Should until then more requests pile up, there'll be another round.

Eventually I will need everyone's mailing address. You can send it by e-mail or PM (don't put it on the forum).

[MitchK]

Hello Martin,

Wow, I just discovered this thread! Hopefully not to late to get in on the first run.

Some background: I've recently discovered the world of homebrew LED systems in general, and homebrew LED generator hub systems in particular.

Your designs are probably the most inspiring I've seen so far. Thanks for all your hard work (an obvious labor of love) and for making this exciting PCB available to CPF members!

I'm a complete electronics novice...not sure I want to tackle a project like this right now, but I will be following this thread closely.

Thanks,
Mitch

[Martin]

MitchK !
Are you saying you want one of these PCBs and you will be using it with a 3-LED headlight ?

Novice ? The circuit is not demanding in any way, no RF tricks, no fast controllers, no difficult soldering, no odd components. However, it's the nature of electronics that if a little detail is wrong, things no longer work as intended. The light could be dim, flickering, dead, too hot, expensive LEDs could be shot.. You have approx 40 components where one or more could be wrong / faulty / reversed / short. You'd remove the circuit from the bike, fix one thing, put it back, ride, still see a problem, remove it, try something else, put it back on the bike.. It could become a frustrating experience.
While the PCB is being made, why not try a few of the simpler circuits here.

[TimLondon]

If I'm not too late can you put me down for 2 PCB for Shimano / 3LED/UK ?

[Leow]

Martin,
I'd like one for :
Hub (Shimano XT or SON)
Probably 3 LEDs (may wan't to try 4 or 6).

Is it possible to add a remote switch to one part of the circuit to force voltage doubling - this would allow you to turn down the light (when cycling behind someone) or simply to save leg power (especially with 6 LEDs).


What is the approx. cost of the components ?

Others,
............ has anyone considered a group buy of the BOM or the switcher chips?

Regards,
Leo

[MitchK]

Hi Martin,
I'd be using a 3 (or 4) Cree XR-E headlight (I want lots of output for commuting). I've seen your earlier designs...but this latest one actually seems "simpler" in that you've gone to the trouble of preparing a PCB.

Thanks for your email, by the way (I sent a reply). If there's room in the run, please put me down for 3 boards (for a 3-4 LED system, generator hub). I'm in the US.

Thanks,
Mitch

[MitchK]

Hi Martin,
I'd be using a 3 (or 4) Cree XR-E headlight (I want lots of output for commuting). I've seen your earlier designs...but this latest one actually seems "simpler" in that you've gone to the trouble of preparing a PCB.

Thanks for your email, by the way (I sent a reply). If there's room in the run, please put me down for 3 boards (for a 3-4 LED system, generator hub). I'm in the US.

Thanks,
Mitch

[Martin]

Project documentation (link to design files above) updated.

Is it possible to add a remote switch to one part of the circuit to force voltage doubling - this would allow you to turn down the light (when cycling behind someone) or simply to save leg power (especially with 6 LEDs).

What is the approx. cost of the components ?

Others,
............ has anyone considered a group buy of the BOM or the switcher chips?

Regards,
Leo

To force voltage doubling, connect pins 5 and 8 of IC1. I will add this to an FAQ-sheet in the project documentation.

Approx cost of the components (without dynamo, headlight LEDs and mechanical parts) is below EUR 10, but depending a lot on where you shop. I order from Reichelt.de and while their resistors are rather expensive, they do sell single components.

Group buy ? This is making it too easy, too many folks are going to build this. It's gonna be a support nightmare for me..

[bbaker22]

oops, forgot my country...US

Thanks,
bbaker22

[Eamon]

Thanking you again, Martin.
Apparently I'm not the only electronics rookie on this thread. I suspect that your idea of "easy" and mine are....different. All part of acquired expertise and all good fun.
Question:
Is there an easily available knowledge base to help complete rookies like myself and Mitch? Something like "electronics for the complete morphodite?". Enough that novices can work out their own capacitor and resistor values, and things like switch placement. Enough that every small adaptation for 2/3/4/6 LED's doesn't get referred to you and others on this forum? It would be nice to be able to read a schematic.
It would also be good to minimize the support nightmare.
On a separate note, is it too late to put myself in for two more of the boards? I'm already in for three, and I would like to up it to 5.

All 5 for hub dynamos, all for 3 or 6 emitters, and all to the US.

Respectfully,
Eamon Stanley

[MitchK]

Hi Eamon,
There's probably some good material online somewhere that others could recommend. Also if you like books, I'm finding that this one (link to amazon.com) is very good for getting up to speed on basic concepts, reading schematics, etc. After spending some time with that book, I'm already finding some of Martin's simpler schematics much less intimidating. My first project will probably be his manually switched high-power circuit on this page.
Regards,
Mitch

[Martin]

Eamon, I hope this is not a panic buy. OK, 5 for you.
I'm trying to put all relevant information into the xls that accompanies the design files (link above).
May I recommend another piece of reading: The datasheet of the LM2907 and its application notes.

If you are really determined to play with the component values of the circuit, you ought to have a basic oscilloscope, two multimeters, a setup where the dynamo is coupled to a motor. Without these things, it's really better to let someone else adapt the values as required. If for example you reduce the values of the tuning caps C1..C4, the voltage across Q1,2 increases. The highest voltage occurs at one specific speed and without thorough measurement, you might miss that you exceed the max rating.

[Eddy]

Hi Eamon,
There's probably some good material online somewhere that others could recommend. Also if you like books, I'm finding that this one (link to amazon.com) is very good for getting up to speed on basic concepts, reading schematics, etc. After spending some time with that book, I'm already finding some of Martin's simpler schematics much less intimidating. My first project will probably be his manually switched high-power circuit on this page.
Regards,
Mitch

http://www.amazon.com/Art-Electronic.../dp/0521370957

This one would be next.

[cy]

any chance a completed PCB would be available?

[iggs]

Martin

I'd like to put myself down for a couple of these please

2 x 3 led hub

I'll email too

Ian