Author Topic: Bth headlamp form (Read 3480 times)

germanxxx · « **on:** 08 Mar 2019 at 00:31 »

Looking for dimensions or form for 1930 bth headlamp. Any help would be appreciated. Similar to the one in the photo.

douglas1947 · « **Reply #1 on:** 10 Mar 2019 at 17:16 »

I will try to send a photo of the 1930 H3 (BTH) lamp of my bike. I hope it will work, I had no success in the last time sending photos to the forum; may be my photos have too many pixels?
The lamp is just off the bike, so It is easy to help you with every measure you want.
Reflector ring dia to lamp is 167mm.

Let me know, what you want to know specially.

Michael

Foppoli Matteo · « **Reply #2 on:** 22 Dec 2022 at 16:27 »

hi Michael, is it possible to have the wiring diagram of this light?
or someone from the group can help me!
thanks Matteo

cycarmark · « **Reply #3 on:** 22 Dec 2022 at 18:35 »

Here's the diagram I used for my B29.

Foppoli Matteo · « **Reply #4 on:** 23 Dec 2022 at 18:14 »

thanks cycarmark for the diagram, will I be able to use a common regulator or will I have to find a BTH? which will not be easy to find!
Thanks Matteo

cycarmark · « **Reply #5 on:** 24 Dec 2022 at 02:12 »

The BTH cutout is not a regulator, but a cut out device. The BTH generator only has the one wire going to the cutout. This wire goes into the generator coils and eventually to ground. If you connected the generator wire directly to the battery, the battery would discharge through the generator, which is the reason for the cutout. Only when the generator develops enough voltage (I think) to overcome the battery voltage, will the cutout allow the generator to be connected to the battery and charge it. It does not regulate the voltage to the battery, the battery gets whatever the generator puts out. This is the way I think it works, but perhaps someone more well versed in electrical systems may weigh in to clarify or correct me if I'm wrong.

I've thought about using one of the solid state cutouts available for old 6 volt tractors in place of the BTH unit on my B29, but so far it seems to be working somewhat, although I am using LED bulbs to reduce the load on the battery and charging systems.

Here is a link to the solid state cutout I am considering: https://www.ebay.com/itm/374241908640

eddie · « **Reply #6 on:** 24 Dec 2022 at 07:48 »

As stated - the 'regulator' only prevents battery voltage from backfeeding through the generator - in which case, the 'regulator' can be replaced with a suitable capacity diode - 6amp should cope (Pancake dynamos were not known for their scintilating performance!).

Regards,
Eddie.

Foppoli Matteo · « **Reply #7 on:** 24 Dec 2022 at 11:35 »

Are the yellow and brown wires going to the "regulator" connected to the ammeter?

cycarmark · « **Reply #8 on:** 24 Dec 2022 at 13:23 »

The brown wire is your battery negative which is connected to ground, which in the headlight is a clamp to the headlight shell. The yellow wire from the cutout goes to the light switch which can connect to the ammeter when it is switched on. The other connection to the ammeter is the red wire from battery positive.

Foppoli Matteo · « **Reply #9 on:** 24 Dec 2022 at 14:00 »

I don't understand, I send the photo of the light, there are only 3 terminals: tail, B+, DYN+

cycarmark · « **Reply #10 on:** 24 Dec 2022 at 16:05 »

That looks like the light socket, but do you have the switch that turns the lights off and on? That should be where you have the connections for the yellow wire and other wires.

Foppoli Matteo · « **Reply #11 on:** 25 Dec 2022 at 15:37 »

photo

cycarmark · « **Reply #12 on:** 26 Dec 2022 at 02:01 »

I think yellow goes to dyn+, red goes to B+, black goes to the tail lamp, and brown to some sort of ground on the headlight shell. The red wire should also go to the ammeter. There must be some wiring from the switch to the light sockets and ammeter, maybe these are under the assembly you have pictured.

Foppoli Matteo · « **Reply #13 on:** 26 Dec 2022 at 07:10 »

from the dyn + with the yellow wire I go to the shutdown device -
from the headlight shell - with a brown wire to the shutdown device -
from the - shutdown I go to the - of the battery
From the generator with the blue wire I go to the + of the shutdown device

cycarmark · « **Reply #14 on:** 26 Dec 2022 at 18:18 »

I would wire it as follows:

Connect the yellow wire to cutout positive. Connect the blue wire from generator to the other cutout terminal. The rest of the wiring should be like in the wiring diagram.

Foppoli Matteo · « **Reply #15 on:** 27 Dec 2022 at 10:04 »

why the other way around?

eddie · « **Reply #16 on:** 27 Dec 2022 at 12:17 »

I have just had another look at the wiring diagram in reply 3, and that cannot work! The horn is shown wired to battery(+), so battery(-) must go to earth, meaning the generator cannot be wired as in the diagram (to battery-), as it will short direct to earth and burn out the generator or the cutout (or both).

Regards,
Eddie.

douglas1947 · « **Reply #17 on:** 27 Dec 2022 at 16:35 »

It is right, what Eddie has written.
The Generator is Positv.
The drawing of the Cutout is not accurate. - The wires to the CUTOUT are just at it (without declaration), but the wire NEGATIV Battery are ending at the FIXING SREW of the cutout for earthing to the frame!

Michael

I find an old photo of my cut out, you can see the old original cable shoe for earth on the fixing srew!

Foppoli Matteo · « **Reply #18 on:** 27 Dec 2022 at 16:57 »

thanks to all and I apologize but I can not understand!!!
can you tell me how I should then connect the cut out mentioned by cycarmark?
Thanks Matteo

cycarmark · « **Reply #19 on:** 28 Dec 2022 at 00:56 »

If you look at the solid state cutout it shows how it should be connected. For negative ground the one side is labeled “arm” this is where the generator blue wire is connected. The other terminal is for connecting to battery positive. Since the yellow wire goes to the light switch and eventually connects to battery positive I would connect the yellow wire to this terminal. So if the generator has enough voltage to overcome the battery voltage and the switch is in the charge or a lighting position the cutout will allow the generator to charge the battery. If not the cutout will not allow the battery positive to back flow though the generator to ground.

cycarmark · « **Reply #20 on:** 28 Dec 2022 at 01:04 »

And Eddie is correct. The diagram is very poor in showing how the wiring goes. But as Michael showed in his picture of an original cutout the wiring becomes apparent.

douglas1947 · « **Reply #21 on:** 28 Dec 2022 at 07:22 »

Mattea,

I think the new cut out has a marking on the label for 2 different possibilities :

- on top for Positive power from Armature
- and down for Negativ power from Armature.

I would use the top position
- wire from armature/generator to positive (the BTH do only positive)
- the other connection on the cut out to the switch - to get connection to Battery.

The fixing slot on the socket is also for earthing/ground, for you Negativ.

I can not help with the original wireing. I have the original cut out without working on my bike. I use a solid state direct in the wire from generator to lamp switch.

Michael

Foppoli Matteo · « **Reply #22 on:** 28 Dec 2022 at 07:51 »

I think I understand, correct me if I'm wrong

cycarmark · « **Reply #23 on:** 28 Dec 2022 at 20:26 »

I think you should connect the yellow wire to the positive terminal on the cutout.

Foppoli Matteo · « **Reply #24 on:** 29 Dec 2022 at 06:31 »

cycarmark this you mean?

douglas1947 · « **Reply #25 on:** 29 Dec 2022 at 06:58 »

I think also it is right to connect the yellow wire to +B on the cutout.
Red wire from Battery direct to switch.
So the Ammeter will work (I hope so!).

I found also an other photo of the BTH cutout showing the terminals:
G - Generator
E - Earth
S - Switch

Michael

cycarmark · « **Reply #26 on:** 29 Dec 2022 at 12:54 »

Yes. I think that would work.

Foppoli Matteo · « **Reply #27 on:** 01 Jan 2023 at 07:17 »

Happy New Year!!!!!!

cycarmark · « **Reply #28 on:** 01 Jan 2023 at 15:26 »

A bright and happy new year to you!