Monday, November 27, 2017

DIY Powerbank 2017-A

In search for an easy to make power bank diagram? Here is one for you.

To keep things easy and simple different modules have been used instead of discrete components which greatly reduces the amount of work to be done however a few capacitors will be needed.

Main features:

1. Use of Lithium Ion cell. 18650 cell with protection will be perfect.
2. TP4056 based Lithium Ion charger.
3. A7530 based DC-DC boost converter. 

Extra components required

2 100uF 16V Capacitor.
SPST switch.

This diagram is easy to understand and make but the main limitation will be the amount of power it can deliver which is not that high.

The modules:

First module that will be used is a TP4056 based single cell lithium ion charger. It charges through a micro USB port which is very convenient. It can charge at up to 1A of current which is moderately fast. This module also has Two indicator LED for showing different status. Link to the datasheet is added to the bottom section of this post where a detailed information on what the indicators mean can be found. The only modification required is to solder one 100uF capacitor on the Input pads, minding the polarity.

4056 Based Lithium Ion charger Module

The second module is an A7530 based DC-DC converter. As you might know the voltage of USB port is 5V where lithium ion delivers around 3.7V-4.2V. So Voltage has to boosted up. This particular module do just that, it has a USB port on the output section that can deliver about 800mA so not that powerful but should get the job done. It comes with a 100uF capacitor on its output so nothing needed there. It also has an Indicator LED on board which will light up during operation.

A7530 based DC-DC Converter

Choosing the lithium ion cell

18650 cell with DW01A and 8205A based lithium ion protection circuit will be ideal for this. If your charging module already have protection you can use unprotected lithium cells as well. Two or more cells could be used in parallel although make sure to use similar cells. The only modification needed here is to add a 100uF capacitor across the cell.


This is how the modules and other parts will be connected. 

Very small amount of soldering has to be done with this project. On the Lithium Ion charging module a 100uF capacitor is soldered across the input pads. From the output of this module two wires run to the Lithium Ion cell. Another 100uF capacitor has to be soldered across the cell. I would recommend using 18650 battery case and soldering the capacitor across it which not only omits the necessity of soldering wires across the cell itself but will also make it easily swappable. From there those two wires run to the DC-DC voltage boost module, a switch can be added between the battery and the boost module to turn it on or off and that's pretty much it. Put everything in an enclosure and you are good to go.


1. Datasheets.
2. My full blog.

Tuesday, November 21, 2017

Single Cell LED circuit with Joule-Thief

If you want to light up a white LED from a single AA/AAA cell with minimum amount of components this circuit will be a perfect fit for you.



25Turn of 26Gauge/0.404mm wire on Ferrite Toroid , shown in the diagram.


1 220ohm


1 BC547NPN


1 White LED.

 How it works?


1. Datasheet for transistor.
2. Visit my full blog.
3. Joule Thief circuit.

Single Cell LED circui with regular components

If you plan to make a single cell LED driver but not willing to use any integrated circuit and only of the shelf products this diagram is for you.

Parts Needed:


1 PN5143 PNP
1 PN3569 NPN


1 1k
1 2.2k
1 3.3k


1 470pF
1 10uF


1 1N5817 Schottky
1 LED White


1 100uH


How does it work?

This circuit simply boosts up the voltage by switching on and off the PN3569 transistor which in turn stores energy in the 100uH Inductor and released. This is stored to the 10uF capacitor through the Schottky diode which turns the LED on.


1. Datasheets of the diode and transistors used in this project.
2. Visit my full blog.


Single Cell High Current LED Driver with LTC3490

If you are looking for a circuit to drive high brightness 1W LED with a single cell this will be perfect.


1. Inductor that can handle 2-2.5A has to be used.
2. To soft turn on the circuit an 1uF capacitor can be used across the 1Mohm resistor.
3. 1W white LED should be used with this circuit.
4. Q current is less than 1mA.


1. Datasheets of the components used in here.
2. Visit my full blog.

Single Cell LED Driver With LT1932


Have you ever tried to turn a LED on with a single AA cell? It wouldn't light right? Because a single cell doesn't have enough voltage to turn a LED on as typical LED forward voltage is about 2V-3V. So if you want to make a LED light up with a single cell you will need something more.

In this post I will write about how to do just that but with good components which will be excellent for a bright LED based torch light running on a single cell.



1. Input Capacitor Must be placed as close as possible with to the LT1932.
2. Rset value of 1.2Kohm is selected to get about 20mA, for higher current check the datasheet.
3. Low ESR capacitor should be used with the output.
4. Low DCR Inductor should be used.
5. For a long battery torch light single C cell will be perfect.
6. 5mm 20mA White LED with reflector should be a good choice for torch.
7. You can add more LED if you want, check the datasheet


1. Datasheets Integrated circuit, diode and LED used in this post.
2. Visit My full blog.

Wednesday, November 1, 2017

Simple Main Line LED Dim Light

If you are planning to make a small mains powered LED lamp you are in the right place.
The diagram is a very minimalist in nature, it is not the best diagram of-course(in terms of power factor) but it surely will get the job done just right. This particular diagram is awesome as low cost dim light.

Components Needed:

Let's look at the components that are needed for this project.
Capacitor - 1 Bipolar 0.22uF, 2KV.
Resistor - 1 470Kohm and 1 470ohm.
LED - 4 of them.


How does it work?

As you can see a very simple diagram, to keep the components count low the bridge rectification is done by the LED themselves which allows us to omit the general purpose diodes that would have been used in this regard.

The load here is just shorted so the light emitting diodes just light up when you put the mains in. The 470 ohm resistor is there for limiting the current and the 470Kohm will drain any charge left in the capacitor after usage.


1. Power factor will not be good as for any other capacitive dropper circuit.
2. There might be flicker.
3. Stray electricity might keep the LED lightly lit even when the switch is not on.
4. This circuit is not mains isolated which means it can't be touched while in operation due to shock hazard.

Visit my full blog!

Monday, August 7, 2017

Xiaomi Mi USB Wi-Fi Internet Sharing

Good evening everyone. So to add more ways of sharing the internet now I'm going to write about a small product that can be used to create an easy Wi-Fi access point to share internet with Wi-Fi enabled devices very easily.
Scope of use:

The device that I'm talking about is this one, Xiaomi Mi Portable Wi-Fi. There are other devices on the market like a simple USB Wi-Fi dongle that can do what it does which is creating a Wi-Fi access point but what good about this product is the software that has made this product very easy to use.

So like I said this product can be used to create an access point. All you need to do is find a computer or laptop with internet and free USB port. By simply installing the provided application you can turn that system into an access point. It doesn't matter how that computer is getting internet from, could be wired LAN, could be wireless LAN, could be 3G/4G modem etc.

Components needed: 

1. Working computer with internet and the software installed.
2. Mi Portable Wi-Fi.

This is what I got in the box or package. Obviously I ordered the black one.

And yes the manual provided here is in Chinese.

How to use: 

First you need to download the software and install it. Installation process is very simple so I'm not gonna go over it but I will put a link to the software down below. You can use this device in two ways, either as AP or as an USB dongle for your system. Let's go over them real quick.

1. Using it as AP.

First open up the MiWiFi application. It should ask you to connect the device.

As soon as you connect the device, you will see it has by automatically created an access point. You can change the name and the password from the main window or from the settings menu. It is a Wi-Fi n device so USB 2.0 port would be enough to handle the speed.

You can see no device is currently connected to it.From your phone or any other Wi-Fi enabled device you can connect to it and use internet.

These are two screenshots from my phone which shows the connected state and the speed you can expect from it. To remind you though the Portable Wi-Fi device is connected on the front panel USB 3.0 port of my desktop and I'm sitting next to it and yet you can see it is not getting full signal. From the PC you can see the 1 device is connected.

The button on the right side of the number of devices connected open up device management window from where you can limit speed for any device, blacklist it or make it administrator.

This is the speed that my computer gets which is directly connected to the router via Ethernet cable. So yes your are losing out on speed while using this particular device.

Sorry about the black bars though.

2. Use as an USB Wi-Fi dongle

The second thing that we can do with this device is simply use it as a Wi-Fi dongle. To do so we have to press the menu button and click IDS_SWITCH_MODE_STATION. (Marked with Red on the picture)

Upon confirming it should automatically switch and now you will be able to see nearby Wi-Fi access points and connect to them if you want to.

If you want to go back to the AP mode simple click on the menu button and change it back to AP.

There are other clever things that could be done with it which I might write about in the future including how to use it with Linux and Raspberry Pi.


1. Price - This is a very cheap product. I paid about half of what an USB Wi-Fi n dongle would cost me here.
2. Size - Very compact.
3. Very easy to use.
4. Speed - Although the connection speed kept on fluctuating I didn't find any problem using internet on my phone through this AP or using it on my PC when it was on simple Wi-Fi dongle mode.


1. Bad design - Hard to get it out of the the cover and hard to get it out of the USB port if the port is in awkward place.
2. Unstable connection - Fluctuates a lot. Even on ideal condition it keeps on varying from 6.5-72Mbps.
3. Wi-Fi standard - This is a Wi-Fi n device, so if you need high speed Wi-Fi, this one is not for you.
4. Range - One small room, that's pretty much the usable range of this product.


1. Link to the software.
2. Link to the official device page.

3. Visit my full blog.