STANDLIGHT CIRCUITS FOR DYNAMOS & HUB GENERATORS

BICYCLE STANDLIGHT AND FLICKER ELIMINATION UNITS

General: The diagrams are correct for most hub generators. For a tyre driven dynamo it will be necessary to electrically isolate the bulb holders or lights from the bicycle frame. In these circuits there are two parts. On the left, the generator supplies the rectifier with alternating current (AC ~/~). On the right, the rectifier supplies direct current to the bulbs, and super capacitors in SL-SC (DC +/-).

SL-SC Standlight Circuit is for Nicelite LED bulbs powered by a dynamo or hub generator. The circuit will deliver flicker-free illumination with any hub generator a few seconds after beginning riding, as the capacitors receive charge. The lights remain illuminated for over 45 seconds after the bicycle stops.

Standlight Circuits SL-01 with non regulated bulbs and a vintage Sturmey Archer Dynohub may reduce rather than eliminate flickering. The voltage while riding will pulse between the applied battery voltage and approximately 6V. Nicelite LED bulbs are regulated and they will deliver constant brightness within this fluctuating voltage range.

The output from a tyre driven dynamo is high frequency and will always appear steady at riding speeds without additional smoothing. However, these circuits will also provide a standlight safety function for dynamo sets.



The SL-SC Capacitor Standlight Circuit is for use with Nicelite LED dynamo bulbs. The areas shaded in green could be fitted inside a light, subject to space available. There are only two significant components - a super capacitor and a bridge rectifier. Just one up to all lights can be fitted. Nicelite dynamo bulbs each require 1W and although only two bulbs are shown in the diagram, three Nicelite bulbs can operate from a 3W generator or dynamo, and four bulbs from a 4W generator. See NOTE, below.

Standlight running time is over 45 seconds once the capacitor is fully charged, which requires about 2 minutes of riding. We have built and tested the SL-SC circuit in house.

The circuit is in use by a customer in France who kindly sent the night photo. The bicycle has a tyre driven dynamo.

COMPONENTS SL-SC

L1 & L2 = NL412, NL432, or NL437R
BR = Bridge Rectifier 1A. Low profile package flat on the circuit board / strip board is suggested
X1 = Regulator XGEN, XGEN2 or XGEN5
1F = 1 Farad 5.5V Super Capacitor (supercap)

ISOLATION NOTE: Either the generator coil OR the bulb holders must be electrically isolated from the bicycle frame to avoid a short circuit at the bridge rectifier (BR). Sturmey Archer Dynohubs and probably most modern hub generators are isolated from the bicycle frame. This can be checked with a multimeter. If the generator coil cannot be isolated from the frame, such as with a tyre driven dynamo, it is easier to isolate the bulb holder(s) with insulating washers and sleeving at the lamp mounting bolt. It may be necessary to convert to twin wire connection.


The SL-01 Circuit is based on the Sturmey Archer vintage FSU unit, but miniaturised. It has been tested successfully by a customer.


COMPONENTS SL-01

BR = Bridge Rectifier 1A
D1 = Diode Rectifier 1A
S1 = Headlamp Switch (if fitted)
S2 = Switch in SL-01 unit
* (optional if S1 is fitted)
B1 = 3 x AA alkaline cells in battery holder
X1 = Regulator XGEN, XGEN2 or XGEN5


* With a Dynohub, S2 will select (a) strobing when moving (Nicelite LED Bulbs), or (b) continuous light whether moving or stationary.

Filament bulbs or Nicelite LED bulbs NL412, NL432, NL437R can be used.

ISOLATION NOTE: Either the generator coil OR the bulb holders must be electrically isolated from the bicycle frame to avoid a short circuit at the bridge rectifier (BR). Sturmey Archer Dynohubs and probably most modern hub generators are isolated from the bicycle frame. This can be checked with a multimeter. If the generator coil cannot be isolated from the frame, such as with a tyre driven dynamo, it is easier to isolate the bulb holder(s) with insulating washers and sleeving at the lamp mounting bolt. It may be necessary to convert to twin wire connection.

FEEDBACK: Customer review M reports on results with this circuit. Customer Reviews




The SL-02 Circuit is based on the Sturmey Archer vintage FSU unit, but miniaturised. It has not been tested and is offered as a suggestion only. We will be very pleased to receive feedback.


COMPONENTS SL-02

BR = Bridge Rectifier 1A
D1 = Diode Rectifier 1A
D2 = Diode Rectifier 1A
S1 = Headlamp Switch (if fitted)
S2 = Switch in SL-02 unit
* (optional if S1 is fitted)
B1 = 3 x AA Nickel Cadmiun Rechargeable Cells
R1 = Charge resistor
F1 = Fuse 1A
X1 = Regulator XGEN, XGEN2 or XGEN5
Bulbs = Nicelite NL412 or NL432, NL437R


* With a Dynohub, S2 will select (a) strobing when moving (Nicelite LED Bulbs), or (b) continuous light whether moving or stationary. Also with a Dynohub S1 probably needs to be open ("off") for battery charging as there may be no surplus power from the 2W Dynohub when two 1W Nicelite bulbs are powered. A charging socket for an external power supply could be included in SL-02.

Two Nicelite LED bulbs NL412, NL432, NL437R will run at their full brightnes (2.5V-6V range) while stationary on battery power only for almost 2 hours with fully charged 1000mAh cells.

Charge resistor R1 value must be chosen to avoid overheating the battery when fully charged. NiCd cells can accept over-charge as long as it is not excessive. Alternatively there are more sophisticated ways to control battery charging with IC chips. In this case other cell types such as NiMh or Li-ion could be considered.

This circuit could be adapted to produce a regulated bicycle 5V USB supply.

ISOLATION NOTE: Either the generator coil OR the bulb holders (lights) must be electrically isolated from the bicycle frame to avoid a short circuit at the bridge rectifier (BR). Sturmey Archer Dynohubs and probably most modern hub generators are isolated from the bicycle frame. This can be checked with a multimeter. If the generator coil cannot be isolated from the frame, such as with a tyre driven dynamo, it is easier to isolate the bulb holder(s) with insulating washers and sleeving at the lamp mounting bolt. It may be necessary to convert to twin wire connection.


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