Bicycle Dynamo Circuit | Electronic Project Circuits

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Bicycle Speedometer With Hub Dynamo

The idea for this circuit came when the author had problems with the wireless speedometer on his bicycle. Such a device consists of two parts: the cycle computer itself and a transmitter that is mounted on the front fork. A small magnet is attached to the spokes so that the transmitter sends out a pulse for every revolution of the wheel (as long as everything has been fitted properly). Since the range of the transmitter is limited (about 75 cm), you’ll be lucky if it works straight away. And when the voltage of the battery starts to drop you can forget it. The following circuit gets round these problems.
A Shimano NX-30 hub dynamo has 28 poles. This results in 14 complete periods of a 6 V alternating voltage per revolution (when loaded by a lamp; under no load the voltage is much higher). C1, C2, D1 and D2 double the voltage of the AC output. Regulator IC2 keeps the voltage to the transmitter and the divider IC at a safe level (12 V, the same as the original battery). The divider chip (IC1) divides the frequency of the signal from the dynamo by 14, so that a single pulse goes to the transmitter for every revolution of the wheel.
Read More Source: http://www.extremecircuits.net/2010/06/bicycle-speedometer-with-hub-dynamo_03.html

Be the first to comment - What do you think? Posted by admin - October 1, 2010 at 12:53 am

Categories: Automotive, Meter Tags: bicycle dynamo circuit, speed meter

Dynamo Current and Voltage Regulator by TL084

Let’s start analyzing the circuit in idle condition, when the engine is stopped. The battery voltage at B+ cannot pass to D+, because D1 blocks it. D+ is at ground level, because of the low resistance of the dynamo between D+ and D-. Q1 is biased off, which leaves the negative side of the entire OpAmp circuit floating. So the complete control circuit will float at +12V, and in this way will bias Q4 fully on. Q4 then holds DF down to ground, ready for dynamo startup, and for using the dynastarter as a starter.

There will be no power consumption other than the very low leakage of some components. Q1 is off, D1 and D5 are reverse biased, Q3 is off, D7 stays far below its conduction voltage, Q4 has an insulated gate, C1 and C8 supposedly don’t conduct DC… Actually, the leakage in C8 is the main current drain, but this leakage gets down into the microampere range when the circuit is connected permanently to the battery. So, this circuit consumes essentially no idling current, while keeping DF grounded for easy dynamo startup.

Read More Source:http://ludens.cl/Electron/dynareg/dynareg.htm
Thank you.

Be the first to comment - What do you think? Posted by admin - February 9, 2008 at 5:49 pm

Categories: Electronic Control, Power supply Tags: bicycle dynamo circuit, shunt regulator, solar cell, TL084

Regulator 6V 3W for a Hub Dynamo bicycle

This is a regulator for a 6V/3W bicycle hub generator system. The purpose is to manage the powering of bicycle lights from the hub generator and from rechargeable batteries, to charge the batteries using excess power from the generator, and to provide intelligent charging of the batteries from an AC adapter, when needed.

The switch has three positions: charge-off-light. In the charge position, the bicycle dynamo charges five AA NiMH batteries if those are drained. If the batteries are reasonably full, then the circuit draws virtually no power. In the light position, if the dynamo’s average voltage is below some threshold value, then the bicycle lamps are fed by the batteries aided by the rectified dynamo If the dynamo voltage is high, the lamps are fed directly by AC from the dynamo and the dynamo excess power is used to recharge batteries. The direct use of AC maximizes efficiency. Additional circuitry is provided for an intelligent charging of the batteries from an outlet using a 12V AC or DC adapter. Practice shows that that additional circuitry may be redundant. A flickering green LED indicates the activity of the dynamo in the charge mode and the fact that the light is fed by AC in the charge mode. A red LED indicates the fast charge state when the charging is done from an outlet.

Source: http://www.nscl.msu.edu/~daniel/sreg.htm