In this post we study a simple rechargeable LED lantern circuit which features battery charging option from a dynamo as well as from a mains 220V source. The idea was requested by Mr. Chidimonday.
The Circuit Request
hello sir, i like what you doing here, i have even put in work some of your circuit and it functioned well, please sir can you help me, am writing from Nigeria, please i need a circuit diagram of 9v rechargeable lantern using dynamo and also electric current, thanks,i will be grateful if you respond back immediately, you can, send it through my Gmail account (email@example.com)
The Circuit Design
The simple diagram presented above explains how a 9V battery may be charged from a dynamo and also from an external 12V DC source simultaneously or separately, and subsequently used for powering an LED lantern.
The opamp IC along with the shown associated component basically forms a shunt regulator stage, which regulates the dynamo voltage and current by shorting its power to ground whenever it tries to exceed the 12V mark.
The controlled 12V is allowed to pass to the connected 9V battery for charging via a LM317 current limiter stage.
The DC acquired from an external source such as from an AC/DC wall adapter can be also seen fed at the input of the LM317 regulator, which is further appropriately trimmed down by the LM317 stage in order to enable a safe charging for the connected battery,
The value of Rx can be calculated as per the information provided in the following article:
Parts list for the proposed LED lantern circuit using a dynamo and mains AC
R1, R2, R3 = 10k
R4 = 6.4K
Z1, Z2 = 4.7V zener diode
T1 = TIP122
IC1 = 741
D1, D2, D3 = 1N4007
C1 = 100uF/25V